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New Solar planning and design guidelines


Sarel
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The can o worms…. 🪱

So you want to go Solar, good choice. But you want to go off-grid? Why, it’s the first question, oh and there is no wrong answer here by the way. Before you even think of answering that question, this is going to be a ‘buckle up buttercup’ question laden thread. Consider this the valley of a thousand questions. So here we have the first real question for ya, why don’t you buy shoes that are half the size you normally wear? See we start easy :) Let me answer that, because you cannot use them and it will be a waste of money. Facts don’t care for feelings…. Now with that out the way, let’s get the tongue out of our cheek. (or should that be shoe 😬)

shoes.jpeg.bdb46a0fc843993ee2deff53b50f0b08.jpeg

Your mind is made up, your budget cast and you have a good waf/haf (wife acceptance factor). So now is the time to hold them hosses, don’t get em cart out in front of them hosses…. Question time then, you guessed it, many many more q’s.

Why, where, when, how much budget, how much consumption, how much diversion (more on this later) and a bit on time warping. OK ok, I just want solar and be done with it already. Well maybe stop reading then and go buy some stuff as this might then not be for you. Or maybe not, Solar has no instant gratification like instant coffee but it can boil your kettle for a cuppa while you think. There is no one size unisex fits all here. Each and every one of these systems are unique to you, so the better you understand you, the better you will understand your requirements and therefore be better informed when having to make choices for better outcomes. If you too lazy to apply your mind, be my guest.

Consider firstly why do you want to install Solar PV? Are you building new or are you not connected to the Utility Grid (be that Eskom or via your Municipality) or do you want a reduced monthly energy bill? What about just being energy independent and not suffer another blackout, or even most of the above?

What does it take to go off grid? That depends, but one certainty is lots of money, frequently more than you want to spend or even can spend. That is just a fact. But lets unpack what a household would need, roughly. I will make em numbers easy so you can calculate along at home. Before we even get there, ha and you thought this was quick an easy…. What can you change to allow you not to consume so much energy? A new kettle o fish to consider as it’s less costly to not consume the energy in the first place, rather than to buy equipment to support that extra load in and off-grid system. Maybe off-grid is not viable and a compromise is needed. This is easy and maybe suitable for you.

So let’s look at the process for going Solar. We have to start by doing all the below, even though it may not be formally, it’s still done, even if only mentally and not really consciously.

  • Requirements
  • Energy assessment
  • Assessment in light of the combined above
  • Planning
  • Modelling
  • Optimisation
  • Design and more planning
  • Procurement & Logistics
  • Build (and the inevitable realisation that you did a piss poor job of planning)
  • Configuration and Programming if required
  • Testing
  • Commissioning
  • Tweaking (you always do this even if you don’t want to)
  • Maintenance.
  • Upgrades and additions

The biggest consumers of energy is water heating by geyser, then kettle, ironing, stove plates and ovens, microwave, underfloor heating, pool pump and spa pump and heater. During Winter it’s space heating and Summer time Airconditioning. Tumble dryer, washing machine and things like Air fryers, hair dryers and coffee machines can have quite a load but their use is less frequent. Can any of these things be reduced or changed to alternative fuels like Gas (diversion of energy sources)? For Petes sake, don’t try and get your women folk to not use the hair dryers please…. Are you willing to change appliances if they not yet working on Gas or solar water heating? That will cost money, but maybe investing here is a bit more palatable then spending the money on batteries for nighttime use. Remember, we asked what it will take to go off grid?

Do not forget about the CoC and other approvals and all the paperwork to be done. For interconnected Grid tied systems vs off-grid systems, there are differing requirements. Starting out, your electrician will most likely have to split the Distribution boards and neutral wires to accommodate the Solar install. All these things take time and money. Don’t be surprised for all the issues your sparky will uncover with the house wiring and general state of affairs, or the costs involved. Over time, your house loads may change, Murphy dictates that this will be an increase of loads. Consider this when planning your system, or later when you are faced with issues during operation. The national codes for House wiring and Solar PV systems are in place for reasons.

What’s to come then (likely each topic will be a post):

  1. Intros, this bit here and now
  2. Setting the scene and asking the questions
  3. Model an average household and see what a reasonable system is capable of, and if it can take you off-grid. A few panels, Inverter, Battery etc. really bare bones.
  4. Model the same household for off grid if the above does not quite make off grid and see what it takes
  5. Do some modelling as to costs and payback and savings, all them boring Financial stuffs
  6. Briefly discuss alternate fuels
  7. Look into the questions and answering all 1000
  8. What goes into planning and how to do so (Fail to plan, and you surely plan to Fail)
  9. Based on the previous, plan a system’s PV Panels
  10. Plan Inverter and battery systems
  11. Monitoring and managing the system
  12. Fallout, do the time warping thing or get your spouse and kids in line hehehe
  13. Living with Solar

How much energy do people consume monthly. Well as always it depends. To make things easy, see my promise earlier, I will use 500kWh per month apart from 3 winter months that will be 1000kWh consumption. This is so you can easily extrapolate and make it work for whatever your numbers are. For electricity kWh costs, I used a number as it varies all over the place depending on supply and where you are and pre-paid or other wise.

So more to follow, all them questions....

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  1. Setting the scene and asking the questions

Introductions done, time to dive right in. This is meant to be guidelines, some items may not apply to you. We assume you want to install a Solar system then since you are still here reading about it 🤔. We also assume you do not want to do the Solar thing twice but just once. Rightly you may wonder why anything I say has any validity at all? As you should. A short bit about me then:

•40 years involvement in technology in it’s many forms

•Designed, Built and maintained TV Broadcast and Edit studios

•Been building encrypted Communications systems and IT systems since 1985

•Consulted to the likes of Telkom and Eskom as a full-time resource for more than 10 years

•Design, Build, Install and Commission Eskom OT SCADA Systems, all of them still running our Distribution Grid to this day

•Design, Engineer, Model, Optimise, Build, Install, Program, Automate and Commission and Maintain Solar systems for 2 decades. My business is in IT, Solar is done as an aid.

•Worked for one of the largest Premier international IT software companies for more than 7 years as a Solutions Architect and Engineer

•Designed build and Project managed Data centres all over Sub Sahara Africa for Mining companies, including power backup systems with Generators and Solar

 

Some random examples of a project I led from inception to commissioning…. No wires or patching cables on the front, all wiring at the back, just the opposite of how it’s still normally done today.

systemfront.jpg.24f7bf0e4b56db06b5e6988f7968caa6.jpgsystemrear.thumb.jpg.eaaa0bbadea5794aa2ccfc38902534c6.jpg

 

 

Question time starts now.

What do you want the system to do?

Be a UPS to just last you enough time to keep the lights and TV on, Internet and the fridge freezer?

Do you want to use Solar energy to run your home on, during the daytime? That means Utility grid at nighttime.

Do you want to reduce your energy bill each month?

Do you want the Air-conditioner in Summer and Space heating in Winter to be run from Solar?

Do you have a Generator, what capacity if you do?

How much space do you have for Solar panels?

Where will the panels be installed, on the ground or on a roof?

What direction would the panels be facing?

Would this be a replacement system or an upgrade to existing or new?

Do you plan on feeding generated energy back into the Utility Grid?

Find out what is involved in Grid feed in from your council, it’s lots of paperwork and costs  for your pocket, if they even allow that.

 

General questions.

Are you prepared to change habits like when to have the Dishwasher operate, during late morning vs evenings?

Do you want to go completely off-grid and not use Utility grid power at all?

Are you on a farm with no Eskom?

Would this be for running a Lodge or a Commercial operation or a House?

How big is your family or business and what are your habits around when you use energy?

What are your monthly and daily energy consumption and peak power requirements?

What do you plan for bad weather days with little Solar generation? And for a few bad days in a row?

Do you have any electrical motors that need to run, Pool pumps or Machinery in a workshop?

Are you going to stay on the property for a period of time or may you move? Think about the investment and the RoI period.

What about upgrades later, how do you plan for those now?

Do you want to finance or pay cash?

What is your budget?

Are you a hands on person or do you want the system to be plug and play and just work with no interventions on a daily basis?

 

Specifics around the Installation questions.

What loads are essential to you?

What loads can be left off during a blackout or failure of sorts?

How many distribution boards on your property?

Do you currently suffer from earth leakage trips where you have to reset the RCD breaker?

Do you currently have a valid CoC certificate? Can you get one pre-installation?

Do you have any Surge protection or Lightning protection rods or any other devices installed in the distribution boards for surge/lightning protection elsewhere?

When will you be able to give access to the installers?

The system must be signed off and a CoC certificate issued at the end of the day, How do you plan to ensure that?

Who will be responsible for the CoC, you or the installer? It is your responsibility to ensure that you obtain a CoC.

What about logistics for delivery of equipment?

If the panels are to be mounted on a roof, what is the roof slope angle and in what direction are the roof space facing?

What type of roof do you have, flat, pitched and tiled or concrete etc?

Are there any existing installations like Solar water heaters or other items on the roof?

Do you have skylights or chimneys or antennas or other protrusions on your roof?

What about things like trees or other buildings shading the Panel area?

How will you deal with this shading? Are there alternative places to install Panels?

 

Caveats, and there are some….

Grid tied systems do not generate energy when there are grid failures, load shedding or blackouts.

Inverters mostly need batteries to operate. This is what allows you to do energy time warping, shifting loads to use energy after sunset.

You will most likely have to change habits by doing more energy consuming tasks during daytime, or still consume from the Utility grid or batteries after sunset.

All this stuffs are technical by nature, some understanding required to operate efficiently.

 

You may not have many answers to all these questions, ignore that at you peril and pocket. Find the answers first. Those answers may very well lead to many more questions, answer those too.

 

Next time we model the solar system for a look see at what it takes….

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24 minutes ago, Sarel said:
  1. Setting the scene and asking the questions

Introductions done, time to dive right in. This is meant to be guidelines, some items may not apply to you. We assume you want to install a Solar system then since you are still here reading about it 🤔. We also assume you do not want to do the Solar thing twice but just once. Rightly you may wonder why anything I say has any validity at all? As you should. A short bit about me then:

•40 years involvement in technology in it’s many forms

•Designed, Built and maintained TV Broadcast and Edit studios

•Been building encrypted Communications systems and IT systems since 1985

•Consulted to the likes of Telkom and Eskom as a full-time resource for more than 10 years

•Design, Build, Install and Commission Eskom OT SCADA Systems, all of them still running our Distribution Grid to this day

•Design, Engineer, Model, Optimise, Build, Install, Program, Automate and Commission and Maintain Solar systems for 2 decades. My business is in IT, Solar is done as an aid.

•Worked for one of the largest Premier international IT software companies for more than 7 years as a Solutions Architect and Engineer

•Designed build and Project managed Data centres all over Sub Sahara Africa for Mining companies, including power backup systems with Generators and Solar

 

Some random examples of a project I led from inception to commissioning…. No wires or patching cables on the front, all wiring at the back, just the opposite of how it’s still normally done today.

systemfront.jpg.24f7bf0e4b56db06b5e6988f7968caa6.jpgsystemrear.thumb.jpg.eaaa0bbadea5794aa2ccfc38902534c6.jpg

 

 

Question time starts now.

What do you want the system to do?

Be a UPS to just last you enough time to keep the lights and TV on, Internet and the fridge freezer?

Do you want to use Solar energy to run your home on, during the daytime? That means Utility grid at nighttime.

Do you want to reduce your energy bill each month?

Do you want the Air-conditioner in Summer and Space heating in Winter to be run from Solar?

Do you have a Generator, what capacity if you do?

How much space do you have for Solar panels?

Where will the panels be installed, on the ground or on a roof?

What direction would the panels be facing?

Would this be a replacement system or an upgrade to existing or new?

Do you plan on feeding generated energy back into the Utility Grid?

Find out what is involved in Grid feed in from your council, it’s lots of paperwork and costs  for your pocket, if they even allow that.

 

General questions.

Are you prepared to change habits like when to have the Dishwasher operate, during late morning vs evenings?

Do you want to go completely off-grid and not use Utility grid power at all?

Are you on a farm with no Eskom?

Would this be for running a Lodge or a Commercial operation or a House?

How big is your family or business and what are your habits around when you use energy?

What are your monthly and daily energy consumption and peak power requirements?

What do you plan for bad weather days with little Solar generation? And for a few bad days in a row?

Do you have any electrical motors that need to run, Pool pumps or Machinery in a workshop?

Are you going to stay on the property for a period of time or may you move? Think about the investment and the RoI period.

What about upgrades later, how do you plan for those now?

Do you want to finance or pay cash?

What is your budget?

Are you a hands on person or do you want the system to be plug and play and just work with no interventions on a daily basis?

 

Specifics around the Installation questions.

What loads are essential to you?

What loads can be left off during a blackout or failure of sorts?

How many distribution boards on your property?

Do you currently suffer from earth leakage trips where you have to reset the RCD breaker?

Do you currently have a valid CoC certificate? Can you get one pre-installation?

Do you have any Surge protection or Lightning protection rods or any other devices installed in the distribution boards for surge/lightning protection elsewhere?

When will you be able to give access to the installers?

The system must be signed off and a CoC certificate issued at the end of the day, How do you plan to ensure that?

Who will be responsible for the CoC, you or the installer? It is your responsibility to ensure that you obtain a CoC.

What about logistics for delivery of equipment?

If the panels are to be mounted on a roof, what is the roof slope angle and in what direction are the roof space facing?

What type of roof do you have, flat, pitched and tiled or concrete etc?

Are there any existing installations like Solar water heaters or other items on the roof?

Do you have skylights or chimneys or antennas or other protrusions on your roof?

What about things like trees or other buildings shading the Panel area?

How will you deal with this shading? Are there alternative places to install Panels?

 

Caveats, and there are some….

Grid tied systems do not generate energy when there are grid failures, load shedding or blackouts.

Inverters mostly need batteries to operate. This is what allows you to do energy time warping, shifting loads to use energy after sunset.

You will most likely have to change habits by doing more energy consuming tasks during daytime, or still consume from the Utility grid or batteries after sunset.

All this stuffs are technical by nature, some understanding required to operate efficiently.

 

You may not have many answers to all these questions, ignore that at you peril and pocket. Find the answers first. Those answers may very well lead to many more questions, answer those too.

 

Next time we model the solar system for a look see at what it takes….

Sarel, another insanely gifted guru. But I knew it , at least I am that clever! I also have the 40 years , but much of it misspent!

Very much intrigued by your involvement in encryption , what a discpline.i myself had been involved in encryption as a secure mechanism for  rail operator to train cab comms in my later years. 

So with reference to SCADA and industrial automation, will you agree that solar discipline is in a mess regarding standards etc. ? Solar is where automation was in late eighties with ad hoc protocols etc etc.  Everyone was just living on an island doing its own thing. First thing solar must get working groups to establish norms and interface specifications. 

 

 

Edited by dropkick
Misspelling
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Could not agree more.  The OEMs are not interested at all. Some or even most of them make an ecosystem of product and they interoperate just fine. Most of the copies out there just don't give a flying rats worth, its just a ripoff anyways. Most politicians don't care as there are no real money in it for them, its not a cause (standards in solar) voters will get behind. Voters are scared for CO2 alarmism and will vote on anything green, but not standards. There are no international organisations, most are politically funded and driven, that will take this on.  For grid scale systems, there are standards, residential and commercial, not really.

I wish I could have a better outlook and answer that some things will change, not holding my breath on this tho….

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Posted (edited)

2. Model a Statistically average household and see what a small but reasonable system is capable of, and if it can take you off-grid (nope). A few panels, Inverter, Battery etc, really bare bones. (Made a number of assumptions, obviusly)

Before we get there, a general comment. The energy revolution is upon us and we are living during a time of great disruption and change. For reasons. Solar PV and batteries are getting less expensive year on year globally, by a significant amount. This is in spite of the global plandemic. Did I just misspell that, not entirely sure but I might not have.

Between the generation and storage getting less expensive, and our own little Socialtopia increasing the energy costs across the board (it’s almost the 52nd Commiefornian state), this disruption to decentralised generation is bound to happen, and soon. And YOU my “comrades” 🥸🥸 are making this happen, you are the bleeding edge of the revolution in energy, the rays of sunshine causing the change, and you should be proud!

Some general background information, ah perspective. 

The bulk energy consumption below, not just electricity but all forms of energy!

608641222_SouthAfricaPercapitahowmuchenergydoescopy.thumb.jpg.7945145f1b4d60f3a326fdc3bea67ffe.jpg

 

Just electrical energy.

164499554_SouthAfricaPercapitahowmuchelectricitycopy.thumb.jpg.7346685ca94c46427ae3bff7c321d68d.jpg

 

And including a more global view on Total energy….

1939282680_SouthAfricaPercapitahowmuchenergydoescopy2.thumb.jpg.0d6c2cc5814b553e90ce1e3554a0379e.jpg

 

Energy consumed by mix.

547621854_EnergyconsumptionbysourceSouthAfricacopy.thumb.jpg.722e1ebb83fc0fae18b5c5e141cc5fc7.jpg

 

Different view, by source.

1398074118_ShareofenergyconsumptionbysourceSouthAfricacopy.thumb.jpg.1415e81331a045b0bcef3f9388effd04.jpg

 

It appears that we consume on average about 20% of energy as electrical energy, the rest from other sources like LPG, Petrol/Diesel, Wood, Coal etc. Average electrical energy consumption per low income person is around 4kWh per capita (i.e. per person living in the house). For middle income people it could be around 8kWh per person and the well heeled sometimes consume around 25kWh per person per hour. For a family of 4, 20-30 kWh per day are deemed to be average for SA. Remember, this is very dependent on the individual’s choices and situation.

From the above, the utter lack of transitioning to cheaper Solar Wind Battery Storage (SWBs) by 2019 is clear, and the initiatives to build any REs, way too late. Much the same still now.

Oh almost didn’t notice but Blackouts are with us again, Eskom is shedding it’s paying customers, ironic innit, seen that many areas with non paying customers are online still 🤔🤦🏻‍♂️. 15MW of unplanned loss of generation and 5MW of planned maintenance, since yesterday. But wait, it’s buylection time again or is it briblection, but maybe I am wrong or mistaken….

Onto more mundane things then ;)

A couple of things to bear in mind. This is and AVERAGE system for a statistically average household, and is barebones. The actual equipment is not significant, just the capacity, ie. Inverter sizing, number of panels, battery storage capacity and your energy consumption. Pricing is based on retail guided price averages not tied to a specific brand, but more to indicate what people are spending. The actual equipment were selected for my convenience, it’s not a recommendation or endorsement at all, it may not even be suitable as a system. None of this has any material influence on the modelling for any of the two systems.

 

System one, barebones: System and costs: (I used a random address in Kempton Park as the example)

barebonesmain.thumb.jpg.e0dd22fa279b577e70884dc187b6c20d.jpg

barebonescompcost.jpg.3dc723615dd5922e079d13e1c0d62196.jpg

 

barebonessystem.thumb.png.b7575f66e417ebf1d89ed26ec9e57c19.png

 

 

How much does the system supply? Your consumption averages per month in solid grey below. Green is how much Solar you can generate with this system.

2122518123_barebonesenergy.thumb.jpg.02218946cd0b6ec1aee016275e91c463.jpg

 

This is the Summer time (same in this model’s case for fall and springtime) energy flows.

Export to grid is only for approved Feed in systems, otherwise this constitutes the wasted energy that could be generated or stored in a battery system.

flowsummer.thumb.png.05c40664010821ee6bcc2a45f02a286e.png

 

And Winter time, as you can see the “Export” number dropped due to the higher Winter time self consumption. Also the Consumption increased.

flowwinter.thumb.png.2b8df7517799beeaa70c41a58138dfb4.png

 

The below shows what this system will do and how much of your monthly utility bill could be saved.

barebonessavings.thumb.png.5c5837aada44e07849eedaa349987663.png

 

And a rough monthly breakdown. Why does the winter months not save anything? Space heating, Water heating and Cooking consumes most of the energy and that normally happens around or after sunset. With little to no battery storage, this is the end result. It’s colder normally, from sunset to a few hours after sunrise, then during most daylight hours.

barebonesmonthlycost.thumb.png.85c3741bb5f30c4a652d495498099da1.png

 

Talking of budget…. This is the real way to look at your budget, what it will get you in savings. Also the energy independence you get if you have battery storage, and that is priceless 😮

barebonesnfi.thumb.jpg.b23dcc656f528e6eb75800153d6c29a3.jpg

barebonesnpv.thumb.jpg.32d57d76a21d2168a2ead8e764d89183.jpg

 

 

Conclusion for the Bare bones system:

Yes you do save costs on a recurring basis. Yes it does take some investment. Your RoI is way more than inflation, way more than money sitting in the bank. Is this costing a lot, yes and no. If you cannot afford this, or rather think you cannot, consider what this modest investment will save you over the 20 year period it’s predicted to work for.

Can this system take you off grid, no. Can you build or expand on this system to do so, yes. It may require to charge the inverter or getting a second inverter. It will need more batteries, and maybe you will have to sell the current battery you have and get a newer or different set, more suited to off grid and more efficient when multiple batteries must be coupled.

 

Next time, can we go off grid now please….

 

barebonessystemcomponents.jpg

Edited by Sarel
added about making assumptions.
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@Sarel, how many people out there do you believe are exporting or can export to the grid, City of Cape Town, even the lead solar person admits that the cost of the bi directional meter makes it not feasible to do feed in

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Posted (edited)

In SA, it's a kak really really bad idea, my personal opinion and I do think that few people do feed in. Until such time as there are legislation in place allowing a separate grid from Government, it will never make sense. A few reasons why I believe it's not a good idea.

  • You spend your capital for the system, they want the energy basically for free
  • You have to jump through arbitrary hoops to get sign off, it costs the council not a dime, you pay them via tax and your council fees, so they just spend your money
  • The money they earn from you does not go to provide services to you
  • Graft bribery and corruption is rife and these laws and rules are abused to their benefit and against you
  • Any meter, old style or new pre-paid can actually meter both ways, why do you think it trips when sensing your side feeding in. Its just set that way in software to discourage you by annoying you and trip, or billing you, same thing, annoying you
  • Some meters will actually read your feed in and bill it as consumption
  • Paying for a special bi-directional meter is therefore a load of kak bs. It's a scheme to discourage you from Solar by making it not affordable to install. It is merely a means to get you to keep on paying for the corruption and enrichment via your energy bill and not endanger the councils biggest income stream

😬accurate enough I trust, no?

 

Edited by Sarel
editing for clarity
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Great guide Sarel & I applaud you for drawing this up on here. If I may add a few points & stresses.

I have found that in consultation with a lot of prospective people wanting to get into Solar. They do not understand the types of questions that you have asked yourself in the above posts. Hence this topic is very important. Then the questions become more & more involved.

I have always started right at the beginning & its close to the same as buying a car. How much do you have to spend?? This is the most important question. What is your budget? If you tell me this ,I can then tell you what solution that type of money can buy you. 

I can tell you a lot about nothing unless it's inline with what your budget can match. So the conversation unravels. 

Many people who do not understand the economics behind Solar need to ask these hard questions and be honest:

1)What's my Budget ?

2)What are my expectations?

3)What is the return on investment?

After these 3 questions are answered you will know how deep down the rabbit hole to proceed. 

So before I try to discuss anything, your budget will determine very quickly where we can you can go together.

Don't get me wrong folks, it's not to rip you off or to pull the wool over your eyes but we need to know each others expectations & from the off I'd say. 

Thereafter we can discuss the bigger picture of your expectations. Some ppl want the Aston Martin of systems. Then they find out that the Toyota also does the trick & reliably so. Then others go for even further down the price scale to the second hand market in which there can be really good value. All of these options can be explored after we know each others expectations.

Germiston has a major problem in Gauteng & are effectively at the mercy of a very dodgy grid supply. It's like eating at a restaurant with poor food quality, rude staff & the food takes ages to come & then when it does it's cold. Then continuing to visit the same restaurant over & over.

The problems Solar has is that it's Capital intensive. People will spend on a performance exhaust or some other crazy non necessity, but not electricity. Why because they don't see it as something to spend on. There are needs & wants. We all need electricity. 

Otherwise great topic Sarel, this is a great education for people kicking tires & doing some digging into the subject. 

87

 

 

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No off-grid simulation models yet 😕 

We do have a whole host of elephants in the room tho (I will refrain from saying bull in a china shop 😊)

  1. Bad whether days or weeks, how will your system cope during a single or multiple consecutive days of rail or cloud cover?
  2. Summer vs Winter rainfall areas and the varying amounts of sunshine and cloud for your specific location
  3. Eastern and Western regions of the country and their varying weather and cloud cover as it differs between east coast and west coast areas
  4. The number of PV panels required to cover for cloudy and rainy days vs the number you need for sunny days. This is at best a thumb suck estimate, you can gat best guess how many cloudy days will bi in the future, use this to estimate the amount of extra PV to compensate. Your Inverter’s PV capacity has some influence on that, sometimes called over dimensioning. Current over dimentioning is ok, but Voltages beyond the max input is a no no. This is compounded as you move further northwards by getting less Sun hours based on seasons, but also as you move from Summer to Winter rainfall areas you need more panels to generate more energy from less Sun due to rain or Cloud during winter months. For Summer rainfall areas, mostly the Highveld, winter days have fewer cloud cover days than other areas.
  5. See cover by month here:  There are maps like this for each months average. The below is Afternoon cloud cover for July, please consult the link to prevent misinterpretation of this data.182700082_Screenshot2021-10-10at10_47_46.thumb.jpg.e28c6f3f308be304bd84c108ecc5d798.jpg
  6. Panels do degrade between roughly 0.5 and 1.0% per year over the first 10-15 years, most of them stabilise after that. You can expect ~80% of nameplate performance for many decades after. Since the panels require no maintenance and no money to keep operating, they essentially generate energy for free after the break even period, apart from cleaning and washing them periodically that is.
  7. Damage from hailstorms or wind (wind damage is normally to the supporting structures, but if that gets damaged, the panels may suffer debris damage or impact damage from falling).
  8. Energy rights, you have none…. Have a think on that...
  9. We as citizens do have a bill of rights as part of our constitution. Consider the worth of that versus the reality of rights in SA. There is no energy rights defined, at all. The word energy is never mentioned in the Constitution and bill of rights. Currently there are only anti energy rights, Eskom as a monopoly for example and the Energy bill. Why do we have the competition commission then? There are no competition allowed in the Electrical energy domain for any practical purpose, and by definition, you do not have energy rights because of that. You as a citizen cannot sell you generated energy to anyone apart from Eskom or your Municipality, and that ain’t no freedom at all but the exact opposite.
  10. Energy is fundamental to life. You need energy to breathe. That energy comes from food. To grow food requires energy, various types of energy are needed like sunlight, water, nutrients, CO2 etc. You also need energy to prepare the food, to keep yourself warm during winter, to save your food from rotting etc. Talking about a fundamental right, energy ensures right to life.
  11. A/C and space warming. First the definitions: The terms COP (coefficient of performance) describe the cooling efficiency of air conditioners and EER (energy efficiency ratio) or HSPF (Heating Seasonal Performance Factor) describe the heating efficiency. HSPF is a measure of the efficiency of a system in heating mode, not in cooling mode. The main reason for considering an A/C unit of the heat pump veriaty is that you get between 1x to 3x the heating per kWh consumed, compared to resistive type heaters where that ratio is at best 1 to 1.

Watch out for these, our Summer is in the middle. Its starts on July! The Sunny (Cloudy days in brackets) for various places, search your own for specifics.

Pietersburg

47471539_Screenshot2021-10-10at08_28_25.thumb.png.31a9d94136b45e1b59afa0f3ba36589a.png

 

Pretoria

9021010_Screenshot2021-10-10at08_28_39.thumb.png.ec7df111f7821adc2c80c0f832582429.png

Bloem is lacking in that data 😕 

1034798261_Screenshot2021-10-10at08_29_39.thumb.png.805126a7c99e034de8839838a37e9bd3.png1358100309_Screenshot2021-10-10at08_30_01.thumb.png.5d67d40448e77a1c98dec25f5511028d.png

 

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  1. Model the same household for off grid if the first model does not quite make off grid and see what it takes

 

Can we go off grid now please….

 

Lets compare, original barebones on the left, off-grid model to the right, and no, you cannot go off-grid with the barebones system. Well not if you continue to consume the same amount of electrical energy.

1364807211_Screenshot2021-10-11at07_03_24.thumb.png.70006e6c3577e94e0e59efb3eb652932.png

Upgrades done from barebones. Increased the number of Panels, changed the Inverter for a 8kW unit and added battery capacity to last for a winters night.

Things to keep in mind. Panels do not face true North, panel tilt angle 20deg. I just added battery packs as if you were expanding the barebones system, but had to change the inverter to cope with the panel string voltage.  If the original inverter could cope, you could leave that alone as well, so purchase a HV PV model in the first place. When designing, keep future requirements and expansion in mind. Always design for the end game, or what you believe the end game can be, that way you can prevent extra work and upgrades in future, sometimes.

For both these systems, the RoI is better than most other ways to invest money (this is not financial advice as I am no financial advisor, please do your own validation). The smaller system has a better returning and lower cost of energy but the bigger system save you more and gets to reduce your monthly bill to basically R0.00 if you had a bill at all. The bigger system also makes you independent from energy price increases (funny how you never see a decrease ne), availability issues and gives you full control over your energy production and consumption. Just the annoyance factor elimination may be worth investing in Solar, any Solar. That and the energy independence is priceless.

 

Comparing the performance from a generation and consumption perspective.

1998693581_Screenshot2021-10-11at07_06_55.thumb.png.1babc36ce5447589ddcb6e44ab703e06.png

 

With the barebones system, we not generating enough solar to cover our loads  completely. There should be enough to recharge the battery and carry some of the load during daytime (and the option to charge batteries from Utility grid is there). It should cover some load shedding or blackouts rather well but. That kinda depends on how severe the blackout levels are.  For the off-grid modelled system, to be able to carry all loads and recharge the battery system at 26.4kWh, we need a bit more Solar panel, in this case 20 panels. For the Summer, Fall and Spring seasons, we should have enough panel to cover for a day or a few days of overcast or rainy weather and still carry loads and recharge batteries.

During Winter however, this may be challenging. Purposely, I did not optimise the panels for Winter generation bias as that will mean a non standard roof installation, and extra time and costs. Optimising the panels for Winter production in this case may just reap enough extra energy to cover battery charging back to 100% and carry all loads. That will have to be determined for each case tho. In an off-grid install, there is no feed in to any grid at all. So excess energy generation potential will go to waste, ie not generated as the system will be throttled, if not self consumed. This is where Hot water storage will benefit, as well as Heat pump Airconditioners due to their heating efficiency as well as its cooling efficiency. We can discuss why this is so for heat pumps later.

Savings.

319096264_Screenshot2021-10-11at08_03_44.thumb.png.1f6d9acb5085db62e394c46628fbe5aa.png

This is the influence on your monthly bill for each of the 2 systems.

 

What is the break even point for these systems? Comparison between the estimated net savings for each system and the break even time period.

723362299_Screenshot2021-10-11at19_37_30.thumb.png.a499953c82514c5cead1db28dea1a5cd.png

If your requirements are for a simple system to beat load shedding, you do not need much in terms of equipment. As is clear from the above, a relatively small investment (not these numbers or these specific equipment pieces) will get you to your requirements. If you have more of a lofty goal, you will need a bigger budget to get where you want to be. These two options used here are for illustrative purposes and should serve as a guide of what is involved.

 

More on this financial aspect later....

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On 2021/10/08 at 1:59 PM, Sarel said:

Are you prepared to change habits like when to have the Dishwasher operate, during late morning vs evenings?

THIS! I find it an on-going struggle. I thought that there would be a learning period - including us learning what to run when - and then routine would set in. But no... 

First problem, and I blame myself for it, is that it didn't occur to me that the thing would be load limited on the output side. So we do run our dishwasher, our kettle, our hot water heating, our microwave on the backed up side, but we can't run them all at the same time. Doh! Of course there's a limit. Why didn't that occur to me? I should have clarified this at purchase time. Anyway, that has been solved by the "rule of two": Look around the kitchen and take note of the microwave, the dishwasher and the kettle. Are two of those on? Then you can't turn on a third. This is not a technically perfect rule (the dishwasher doesn't draw a lot for it's entire run time, and the rule allows headroom for the heat pump) but it gets the job done.

But 2 years later I still have conversations that include the sentence "but the sun is up". That can mean anything from "I have to wear sunglasses inside the house" to "I can see a crack of light through the curtains." Well yes, the sun is above the horizon, but what about all those white fluffy things up there too? Again I have a rule: don't do stuff before 8 am and after 4 pm.

There's more science here (or more demonstrable science). I can show that on a nice clear day like today we are getting about 700w of PV at 7:30, but around 2 KW half an hour later. And I can show that on an overcast day those figures go down a lot. But somehow this doesn't sink in and I get regular reminders that "the sun is up". Well, it IS above the horizon, and we don't have to drive with headlights on, but that doesn't necessarily mean that we are getting a lot of PV. 

Because what is electricity really? It's a convenience. We expect it to just be there for whatever it is we want to do. And compromising on that goes against the grain a bit.

So this is a very good question. Because for some folks having to change their lifestyle is not an option. They don't want a "rule of two". If they want to shower at 2 in the morning and then run the espresso machine and heat up a convenience meal which they will eat whilst chillaxing by watching the tropical fish in the heated tank... well at the very least a system that works for me won't work for that guy.

In the meantime I've had to learn how to operate the dishwasher.

Edited by Bobster
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This is such cool advice from @Sarel. I can't say my system has failed me, but it is right on the edge, and so compromises have had to be made (hot water bottles instead of electric blankets for example), and it hasn't taken my off grid. I pretty much am on a day like today (just as well because we won't have grid for a total of 5 hours today), but if we have 2 or 3 consecutive overcast days then I'd have to start using some grid power. And it's going to be hard to extend this system, although it meets our current needs. I could have done my homework better, but I didn't know what homework to do.

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52 minutes ago, Bobster said:

And it's going to be hard to extend this system, although it meets our current needs. I could have done my homework better, but I didn't know what homework to do.

@Bobster, I have seen this repeated so many times, and it’s sad. We all have to pay our school fees but it is so easy to be prevented by a little forethought. Hence this series of posts. I consider it my contribution to this community. Hopefully it will help many more with some insights into how to approach Solar PV.

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Hi, I would like to know if our energy consumption of between 5-7kWh is realistic🤷‍♂️ and if so, then a barebones system should be able to take us off-grid? To give some perspective we spent R250.00/month at a rate of R1.68/kWh (VAT incl.) so we would have a little over 100 units per month.

 

We have made some extreme lifestyle changes: no geyser (boil pots of water on gas or fire), use gas and braai for cooking, old-school dishwashing (i.e. no dishwasher), no AC (a scorcher in the Karoo). But we still have wifi router running 24/7, both PC and TV on for at least 8hrs per day (kids are homeschooled), fridge/freezer running 24/7.

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Wahki, it depends on what off-grid means to you. The barebones system can supply about 3800kWh per year. That is 316kWh per month or on average 10.4kWh per day, no bad weather days, snow or cloud cover accounted for really. To be able to answer that you really need to understand when you use that energy, what your peak consumption is in kW and when this happens. It is vitally important that you also calculate accurately what appliances consume how much power and when, during daytime or after sunset. If any of the bigger loads happen after Sunset, then the battery will be too small. A lot of buts and ifs in there. You will have to start calculating and work that out in more detail I am afraid.

Consider when appliances like the TV and fridge and or freezer are running with the WiFi and computer, cellphone etc. You have to account for your usage patterns and only you understand that.

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15 hours ago, Wahki said:

Hi, I would like to know if our energy consumption of between 5-7kWh is realistic🤷‍♂️ and if so, then a barebones system should be able to take us off-grid? To give some perspective we spent R250.00/month at a rate of R1.68/kWh (VAT incl.) so we would have a little over 100 units per month.

 

We have made some extreme lifestyle changes: no geyser (boil pots of water on gas or fire), use gas and braai for cooking, old-school dishwashing (i.e. no dishwasher), no AC (a scorcher in the Karoo). But we still have wifi router running 24/7, both PC and TV on for at least 8hrs per day (kids are homeschooled), fridge/freezer running 24/7.

You can go off grid but it will be best to keep the grid connection as back up of get a Geny in case of long rainy days and winter. A 5Kw Inverter with 12 x 400W PV Panels and 4.8kw of Lithium batteries will do the job. But if you spend on R250 per month, going off grid will be a waste. It will be better just to get an inverter and Batteries as back up for power cuts 

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14 hours ago, Sarel said:

Wahki, it depends on what off-grid means to you. The barebones system can supply about 3800kWh per year. That is 316kWh per month or on average 10.4kWh per day, no bad weather days, snow or cloud cover accounted for really. To be able to answer that you really need to understand when you use that energy, what your peak consumption is in kW and when this happens. It is vitally important that you also calculate accurately what appliances consume how much power and when, during daytime or after sunset. If any of the bigger loads happen after Sunset, then the battery will be too small. A lot of buts and ifs in there. You will have to start calculating and work that out in more detail I am afraid.

Consider when appliances like the TV and fridge and or freezer are running with the WiFi and computer, cellphone etc. You have to account for your usage patterns and only you understand that.

Thank you for this Sarel! I think the mistake that most make (preaching to myself here) is that we look at our current Eishkom consumption and measure that against what a "barebones" system can provide daily, but we don't take into account when that power is actually consumed...and this is where we really need to sit down and ask those tough questions that you started this discussion topic with.

What we've done is to measure our energy consumption from around 6pm-7am (roughly autumn time closer to winter) and then the overall daily consumption, this helps to give an idea of what the "night-time" usage is which will (almost) dictate how much battery capacity (plus about 30% up from that) one needs in order to function when the sun is down (would you say this is a good way to go, for the non-pro?). And again, lifestyle plays a key role here...are you willing to change habits to accommodate your new "barebones" system, or do you want your system to accommodate your current lifestyle, I think this is critical.

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4 minutes ago, hoohloc said:

But if you spend on R250 per month, going off grid will be a waste. It will be better just to get an inverter and Batteries as back up for power cuts 

Thanks hoohloc, appreciate the suggestion. I hear you on this point, and I have come to the same conclusion...

However, our living situation has changed and so we are forced to go off-grid, so it's more of a do or die situation for us. In our case we have had to hitch the cart before the horse, and are now slowly getting the horse out to the front:-)

I am still learning and so find this kind of information very helpful. Being situated where we are it has been quite a challenge to get relevant information from suppliers/installers, so I have had to educate myself in order to give a supplier/installer an idea of what our needs are.

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More better later, is now :) We continue with the models. Also, as to costs and payback and savings, all them boring Financial stuffs….

 

Energy flow and the typical usage for a home. In the below we can see when, on average, people use energy in comparison to when Solar energy Is generated. Above the Zero line is generation, and below it is consumption. This makes it clear why battery use is so important. The grey parts of the graph is energy consumption that cannot be satisfied by either Solar generation or battery supplied energy. This means the following, If you have only a few panels and the grey part of the graph overlaps with the yellow Solar part, you do not have enough panel. Early morning and late afternoon this is normal as the Sun is rising or setting still. During nighttime the only way to not be a net consumer (ie from the Utility grid) is to have alternate generating capacity other than Solar, or battery storage of sufficient size.

 

Compare the barebones system to the off-grid one above to see the effect of enough Solar panels and battery capacity. These two parameters were the only changes between the two systems affecting energy flow.

86809611_Screenshot2021-10-13at11_32_00.thumb.png.28b4874205254f12bdbe84e205b39c67.png

For Winter below, in comparison to the other seasons above, we can see that the energy usage pattern differs a lot. During Winter use, we have almost no excess energy (export) for the Barebones system and 44% less energy excess during the daytime.

110752798_Screenshot2021-10-13at11_33_40.thumb.png.2ccfaa4b0d56ed4f67f70e8d2495f9cf.png

 

Here we are looking at the financial comparison. The difference is clear. Remember that Values below is actually your future savings projected to today in today’s value of your money. The blue on the flows are battery capacity being used to carry the loads above the Zero line, below the line is battery charging.

1252252695_Screenshot2021-10-13at11_38_05.thumb.png.1b95d448008faa416d95e946473fc1f1.png

 

Again I need to stress, this is not a systems design. You cannot use this system, any one of these two designs, to build your solution as this is far too simplistic and was only put together to ba able to this comparative modelling. It is merely done to give you the insight what to look for and how to got about YOUR planning. We will show you how to do this planning in a future post, but you need to do that planning, or pay someone to do that for you, or ask on the forum here for advice etc. You need to find the equipment  brand at a suitable price to make this work for you.

Also important is how you look at off-grid. You have to make a choice on a few things. Do you want to spend anything on a monthly bill? Do you want to keep the Utility grid and still consume energy from there? Are you looking for just blackout protection to ride out the Utility grid failure? All these items have a material influence on how you approach your design. For some people it's simplistic and their requirements will be different from yours or my requirements, only you know what your requirements are. There are a number of pre-packaged solutions and DIY systems out there, all of them are based on some requirements.

The only thing you have to base your decision on are your requirements, so better get to know that intimately. If that is not the first thing asked, about your requirements, assumptions were made and those assumptions in your case may very well be incorrect, resulting in a system that may not be suitable to varying degrees.

Next time, Alternate fuels and ways to reduce the electrical loads.

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Alternate energy or fuels, what ya mean alternate, energy is energy, no….

 

Well yes and no. Let’s unpack this a little in terms of Solar generation. There are two ways we can harvest enough Solar energy via Solar PV panels. One is to generate enough to cover our consumption 100%, the other is to reduce or electrical energy consumption by changing over to other forms of energy, normally chemical (fuel) energy or other forms of Solar like direct water heating. This will reduce or electrical energy consumption, sometimes by a lot.

In SA, our fuel prices are well regulated. All fuel types BTU values per unit is known and the relative pricing is done accordingly. Here is a table for clarity sake:

4631755_Screenshot2021-10-14at12_12_37.thumb.png.49411f12a9a08166407c63614c4e8f25.png

Let’s compare electricity to LPG gas and to Diesel fuel. First LPG and Electricity. LPG gives 24 098 Btu per Liter (or 45 545 Btu/kg) and it’s density is 1.898 kg/m3 (15°C) (roughly 1.89kg/L). Let’s work on the average price of R30.00 per kg for LPG and electricity at R2.00 per kWh. For the same Btu value, electricity will need 13.34x more units to get the same value and will cost  R 26.68 vs R 30.00/L for LPG. See what NERSA is doing here? Anything that directly competes with the Utility grid ne, priced out of the market.... Obviously the LPG price differs per region and there are similar differences for Diesel, but suffice for this demonstration to use averages to illustrate the tight control over our energy prices.

Diesel is very close to half the density of LPG.  Diesel gives 36 675Btu per litre (or 32 090Btu/kg) thusly you need 10.75x electricity units to match Diesel’s energy or R 21.50 worth of electricity vs Diesel cost of R 17,60/L at my last refill. So diesel based fuel heaters may work out better for Winter space heating and LPG and electricity more expensive. All of the previous will only be true, heavily depending on the relative efficiency of the heating systems. We will talk about the spanner in the works a bit later ;)

First let’s tackle water heating by other means, apart from direct resistive element heating. Normal electrical elements gives you a 1:1 ratio (or very close to 100% efficiency) for the energy input to heating output, be that for space heating or water heating. If you offload a geyser from the Utility grid, you could save a lot of electrical energy. Let’s go then…. Heating of 150 Litres of water, from 20C to 65C will take 4hours with a 2kW element, roughly then 8kWh or R 16.00.

1588226129_Screenshot2021-10-14at13_06_07.png.9aa01b9b01e6ce16f4fcab159f802c21.png

 

After using water for a bath or shower, you may need to heat from 40C backup up and this will need 4kWh or R8.00 and doing this twice a day means roughly R 16.00 in heating costs per day. We not accounting for heat losses here and these losses will increase costs.

1995160645_Screenshot2021-10-14at13_14_25.png.78d77c76221634ea37ea6a9ecb02fd50.png

 

Direct Solar water heating is one way to save on most of the Utility costs. The actual heating of the water is free after the capital costs are accounted for. Another way to heat water is by Heat pump method, not discussed here. Another way is by changing water heating to LPG gas heater so saving on the kWh costs and shifting it to LPG Gas costs. All these alternate ways of heating your water means you require less Solar PV, and thus costs, and less Battery storage costs, making the Solar PV system more affordable. But, you still have to invest and pay for the energy to heat in some form, even for the alternate methods.

Cooking can be done on alternate fuels as well. You get Solar cookers that use Sunlight, you can Braai cousin 😕 , or you can use a Gas stove. All these alternative fuels for supplying energy can be considered and used, depending on your requirements and lifestyle and need to save on the Solar PV systems costs. This could mean you can afford a smaller and less expensive system, if you offload some of the energy to other types of energy for those tasks.

Always remembering, this is just a guide and only on here to be a guide, and to prompt some considerations. Consider this, anything Solar from direct heating of water to Solar PV, the cost of the actual energy is free for ever from the point of break even. Bar the maintenance costs, you do not pay anything for the actual energy! Any chemical fuel is like a drug, so is Eskom, you keep on paying…. 😕

Now for the spanner in the works….. Heatpumps. These things are amazingly efficient. Depending on the outside temperature, Heatpumps may harvest up to 3 times the Btu energy from the Air, compared to the Btu from the kWh they consume to harvest. This holds true, roughly, for the Airconditioner or water heater types. There are however the substantial up front cost to purchase the unit.

Next

  1. Look into the questions and answering all 1000…. Well maybe not, YOU should answer them. A number of answers were given for these two designs already. For the rest of these we will answer some more in the following section:
  2. What goes into planning and how to do so (Fail to plan, and you surely plan to Fail)
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Hi Newbie Dave here,

Thank you Sarel and others for sharing this invaluable knowledge.  Currently I have  off grid solar heating for my 150 liter geyser ( 4 x 330w panels in series coupled directly to the geyser via electronic thermostat and 30amp solid state relay  with 10 amp fuse protection for the panels.) We are planning to install   a 5kw inverter with 7 x 490w panels to power all our other needs with 11 kw lithium battery bank. We consume 8.5 kw per day. We wish to make provision for a standby generator for the cloudy dark days.  Question:  what kw output generator should I be making provision for?    Question: should I increase my battery bank to 15kw as our intention is to be off grid .  We can be comfortable using only 6 kw per day for 4/ 5 days . we  have gas hob and oven, led lighting  etc .Happy to leave the geyser as is with its separate solar generator, has been paying for itself for 4 years already. Budget is in place for the next phase. 

Any feedback will be very much appreciated.

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Other will chime in, only addressing the generator here. Firstly, almost all smaller generators specifications are overly generous, by a lot…. Secondly, stay away from inverter generators, they have their place but not in Solar systems. They are very bad in high demand and fluctuating load scenarios. You cannot easily determine their response as in overload conditions, they prevent the rpm from dropping by just limiting the load. Stick with old style AVR types. Then oversize the generator capacity by at least 20-30% or even more if you can. Battery charging is the toughest loads for a generator to deal with. Oh and small generators are all specced to standby duty, not prime. 

This is from a generator manufacturer as to their duty cycles:

Standby Power Rating

Standby power rated generators are the most commonly rated generator sets. Their primary application is to supply emergency power for a limited duration during a power outage. With standby rated generators there is no overload capability built into the units. It is important to note that standby rated generators, under no circumstances, should run in conjunction with a public utility source.

Standby power rating should be applied to the unit where public utility power is available. The typical rating for a standby engine should be sized for a maximum of 80% average load factor and roughly 200 hours per year. This includes less than 25 hours per year of running time at the standby rating. Standby power ratings should never be applied except in true emergency outage situations. Predetermined outages with the utility company, under UL guidelines, are not considered emergency outages. Manual load shifts for testing purposes can be performed with most automatic transfer switches.


Prime Power Rating

Prime power rated generators should be used in applications where the user does not purchase power from a public utility. Prime power applications fall under two distinct categories:

Indefinite Running Time

The prime power rating is the maximum power accessible at the variable load for an unlimited number of hours per year in a variable load setting. It is not advisable that the variable load exceed 70% average of the prime power rating during any operational period of 250 hours. If the engine is running at 100% prime power, yearly hours should not exceed 500. Overload situations should be avoided however a 10% overload capability is available for a 1 hour period within a 12 hour cycle of operation.

Prime power is accessible for a limited number of hours in non-variable load situations. Limited prime power is intended for circumstances where power outages are expected, such as a planned utility power reduction. Engines in generator sets may operate up to 750 hours per year at power levels less than the maximum prime power rating. In these situations it is important to never exceed the prime power rating. The end user should be aware that constant high load use will reduce the life of any engine. It is recommended that any application requiring over 750 hours per year that the engine be continuous power rated.


Continuous Power Rating

Continuous power rating is used in applications where supplying power is at a constant 100% load for an unlimited number of hours each year. Continuous power rated units are most widely used in applications where the power grid is unreachable. Such applications include mining, agriculture or military operations.


Elevations and Temperature’s Effect on Power Rating

Elevation and temperature are factors to consider before rating the engine. The engine may be operated at 3,000 ft. of altitude and at a temperature of 100° F without deration for standby power rating. For prime power rating the engine may be operated at 5,000 ft. of altitude and at a temperature of 100° F without power deration. For continuous duty operations at higher altitudes, the engine should be configured to limit performance by 3% per 1,000 ft. of altitude and 1% per 10° F inlet air temperature.

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Thank you Sarel,  you have certainly helped me to narrow my options. I have taken note of your observations with regard to the old style AVR type. I also appreciate your advice as to over-sizing the generator. I certainly wasn't aware that charging a battery with a generator was the hardest workload. since that is the primary reason i require a genrator i will much rather look at a 50% higher rating as i wish to get at least 10 years of usage from the generator. I am sure this info will assist many others like me.

I am equally impressed with your the speed of your reply.     mucho gracias

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Lastly on the generator capacity you should consider that in an off-grid situation, you generator should have enough power to carry at least some loads and be able to charge you battery bank. Sizing for this is a bit involved. Firstly how much current can you use to charge the battery with, ie. how much can the battery accept safely? Then how much on top of that do you need to carry loads? Can you adjust the battery charger to limit charging current o a lesser value? Or are the charger max amperage less than what the battery can take?

Next point to consider for generator sizing is the bigger the battery, the longer it will take to charge. How long do you have to get the battery charged? All these point will need consideration and compromises as the budget will not be infinite.

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