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Pudljumper

I need help please Guys

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I'm new to the forum and to solar so would appreciate help please.

I've bought 7.5ha undeveloped land in Cape Farms inland from Melkbosstrand 5km from Atlantis. Going to install a container and barn in the next month to start the development.

So, I get Eskom to come give me a quote and they say the whole process takes 180 working days, not sure if they can do prepaid in my area, bla, bla... I take it as a clear sign that I need to go solar right now.

Questions:

My take is that I need to start with a system that caters for the 12m container (which will be in the 280m2 barn) and barn. Then, when we build cottages on the land down the line, each will have its own system. Does that make sense or not?

So Guys, if I need say 600kw pm (does that sound right?) for the barn, what is the best solar system for that please?

I would really appreciate some good, wise advice and help.

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46 minutes ago, Pudljumper said:

So Guys, if I need say 600kw pm (does that sound right?) for the barn, what is the best solar system for that please?

Morning Pudljumper

I presume 600kWh per month roughly 20 units a day. That sounds about right (I am busy installing with a client and his usage is between 20 and 30 units a day. I have discovered that you can do anything with solar if you budget is unconstrained. The problem is most of us have budget constraints and that is where the compromises come in and one has to decide whether the compromises are deal breakers. I really like the idea of modular expansion as the cottages go up later down the line.

Since Eishkom is going to take 6 months to consider your application.  You going to start off-grid. First question you are going to have to answer is what  is the maximum draw at any one time. 5kW  8kW . What are you going be running? Construction equipment? A pump? I run my house off a 4kW inverter. We have to make compromises the microwave and oven cannot be on at the same time and so on. If you consider that we use to run off a generator our current situation is nirvana.  

Your second criteria is how big a battery bank do you need?  Living in the Western Cape you probably need 2-3 days autonomy as you would need to survive the Cape storms.  A wind turbine may be a good investment as the lack of sun is usually accompanied by a fair amount of wind. In a grid-tie system a wind turbine makes no sense but in a off-grid situation and sufficient wind they do. A wind turbine may mean you have a smaller battery bank.  Here is where the compromises really kick in - batteries (even the cheap ones are expensive). Do you buy cheap ones knowing you going to replace them sooner rather than later or do you go for more expensive (cheaper in the long run) batteries that last several years. 

To my mind you need to decide on batteries first (both type and size of bank) and then decide on a compatible inverter and finally decide on  panels. Unfortunately we can only guide you as you will be the one spending the tom.

Give us a idea what you plan to power from the container.

I would visit @Mike at Yzerfontein the trip would be very worthwhile. As @Mark has pointed out Mike has reduced his involvement with solar as cryptocurrency is so buoyant at the moment. MIke is really helpful and I am sure will give you solid advice.

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Thanks Chis and Energy, good info!

The container, converted with a bathroom all insulated with electrics etc, is a temporary dwelling so will run a stove, tv, washing machine fridge, laptops, tablets and other small appliances. The barn will have led lights and light workshop tools. 

I guess I would need to start with 4kw and have a stacking set of inverters to expand if that's possible. 

Lots of space for panels on the barn roof so no prob there.

Will need a split solar geyser Because the barn is 5.5m high at the eaves.

Yes, batteries will have to be modern and long lasting so these things cost $$$.

Thanks, I'll contact Mike as he's also up the road from my plot.

Best,

Vic

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4 hours ago, Pudljumper said:

The container, converted with a bathroom all insulated with electrics etc, is a temporary dwelling so will run a stove, tv, washing machine fridge, laptops, tablets and other small appliances. The barn will have led lights and light workshop tools. 

Straight off the bat, use gas for the stove. Normally gas does not work out cheaper compared to city power, but the moment you go off-grid or involve batteries you're no longer competing with city power, you're competing with generator power. Get a gas stove. Also, get a solar water heater.

Wind turbine might be an option for you. More wind out there on the West Coast. Makes little sense here in the Helderberg.

A visit to Mike is a good idea, though I must tell you, he has a big system with cool toys and not-cheap inverters. You might be tempted to toss caution to the wind! :-)

For the rest, what Chris said :-)

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15 hours ago, plonkster said:

Straight off the bat, use gas for the stove. Normally gas does not work out cheaper compared to city power, but the moment you go off-grid or involve batteries you're no longer competing with city power, you're competing with generator power. Get a gas stove. Also, get a solar water heater.

Wind turbine might be an option for you. More wind out there on the West Coast. Makes little sense here in the Helderberg.

A visit to Mike is a good idea, though I must tell you, he has a big system with cool toys and not-cheap inverters. You might be tempted to toss caution to the wind! :-)

For the rest, what Chris said :-)

Thanks Plonkster, gas stove and wind turbine are both on my shopping list. I'm a sucker for cool toys so here comes trouble!

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Morning Pudljumper,

from your intro it is not clear if you intend to move onto the property immediately or if it is gonging to be a weekend project to start with, the 12 container brings up some clues....

My contribution would be to advise to go slowly and learn organically what works and does not work for you in your specific context. I am playing with cob, permaculture and sustainable lifestyle ideas in Tesselaarsdal (close to Hermanus). One of my first projects was to build a solar water heater which worked perfectly up until the day the copper was exchanged for a papsak. With a lot of wood available, today I work with wood heating a my water in a donkey which also works wonderful. Solar is gaining a lot of traction in Africa, typically one panel charging a cellphone or running a few LED lights therefore solar equipment is becoming sort after, A friend had 10 panels stolen from his roof within a few hours, therefore a generator might be a safer option to start out...

1. I have found that issues like security  of your equipment etc. is also important factors in some cases even more important than the technical specs.

2. Moving from ESKOM to living with solar requires some new skills and attitudes, not just for you but for the family,  again try to go slow, the social cost can easily be more that the cost of batteries:( I started out with the 3kw infini and are learning as I go..

It would be interesting to hear more about your project and best of luck to you

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Morning Green Bum,

Thanks for the info, much appreciated!

We have 3 family members moving from Dbn to live in the container and barn while they build their cottage on the land. So their consumption will be pretty low hence 600 kw pm estimate.

The barn is going to be 5.5m high at the lowest point so panels will be not too accessible to intruders. We're going to take care with security although it's pretty safe as our neighbour has lived there since 1973 without major incident.

We do have lots of wood and said neighbour has been off-grid forever and he has a donkey for heating in his kitchen which works amazingly well. 

Thanks for the well wishes, it's exciting to be doing a project like this from scratch but also so critical that every decision needs to be the right one. That's what I lose sleep about!

Best,

Vic

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2 hours ago, Pudljumper said:

their consumption will be pretty low hence 600 kw pm estimate.

My personal opinion (it has to be an opinion because these things are subjective) is that 600kwh a month isn't that low. It's pretty average for a house in the city. I'd think that you should be able to get by on less than that, especially if the cooking and heating is done using other means. A system that can generate 20kwh a day with at least that much storage is not a small system. You'll need at least 4kwp of PV and a really large battery bank. The kind of battery  you need to buy to store 20kwh will cost between 100k and 200k, and I would advise you to look at the 200k end because that should work out cheaper in the long run (10 Pylontech units). Then another 25k-30k for PV panels, and then an inverter on top of that... you can almost see why the debate around which inverter to buy is almost insignificant at this point, even a nice big 5kva multi is only going to make up 20% of the total cost :-)

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Thanks Plonkster, being a newbie I'm learning all the time and adjusting my perspective daily if not more often!

I saw a system using Imeon 3.6kw, batteries and panels for R100k and thought that would do the trick to start and then adjust as needed. Maybe i'm overestimating the need for 600kwh pm then, maybe, hopefully, it's much lower.

When I read what you say about how much battery power is needed two thing spring to mind:

1. We need to reduce consumption radically- obviously. Gas stove, solar geyser, donkey in kitchen to heat living area and water in winter, inverter aircon for summer.

2. Wind power, we have lots of wind and it blows at night too. That means much less battery capacity required not to mention less panels too.

If we did that, what would our consumption look like and what system would cater to that please in your valued opinion Plonkster?

Best,

Vic

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12 hours ago, Pudljumper said:

what would our consumption look like and what system would cater to that please

It's difficult to say. At the moment, on a good sunshine day, I use around 20kwh of which half is generated by solar. We still use the tumble dryer and that accounts for a good 5kwh a day, we use a microwave oven, cook on an electric stove, and so on and so forth. So thumbsuck, if I tossed the tumble dryer, switched the stove to gas, and get rid of the fish pond with its 24/7 little pump, I'd think that 10kwh a day is doable. For me it doesn't make that much sense, at R1.93 per kwh it still makes sense to cook on electricity, but on a farm it should make sense.

I'm employed by a solar power manufacturer, so I'd rather let the other guys recommend you a system. Technically I already hinted :-)

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Thanks plonkster, ok this is where I display my ignorance:

If I need 10kwh a day is a 3.6kw inverter sufficient and that R100k system with 4 batteries and 12 panels (assume 3000kwh?), will it work?

Or lets get down to basics- I mean, we need lights and we'll use 10x LED so that draws 30w x8=240w, we need to charge tablets and cells (200w) and run a TV (700w) and fridge (100w x 24=2400w) all of which I understand uses 3.54kw per day. 

The pump for the big pond (when we finally build it after waiting for a borehole to be drilled!) will need to run off its own solar power system.

So I need to start with a system to provide us with 4kw per day- could anyone please tell me how to do that cost-effectively?

Lest I be labeled cheap, remember I need to repeat the system for each of the four cottages, so price plays a significant part especially as we still need to pay the cost to build the cottages, fencing, security et al.......OMG what have I gotten us into! :0

Best,

Vic

 

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4 hours ago, Pudljumper said:

If I need 10kwh a day is a 3.6kw inverter sufficient and that R100k system with 4 batteries and 12 panels (assume 3000kwh?), will it work?

You size the inverter for the peak load (your batteries needs to be big enough as well, of course), there isn't a direct relation between the energy required and the peak rating of the inverter. It is perfectly possible to consume 10kwh a day using a 500VA inverter... if it runs at almost full capacity all the time (0.5kw*24 = 12kwh). In other words, yes, assuming you don't have loads over 3kw, the 3.6kva unit should be sufficient.

To store 10kwh (or thereabouts) in lead acid batteries, you'll need at least 4 x 200Ah 12V batteries (48*200 = 9.6kwh). But lead acid batteries don't like to be taken down to zero, you want to keep them above 50% most of the time, so you will need double that. Parallel strings (ie 2 strings of 4 batteries each) don't work as well as one larger string, so I'd advise you to look at 400Ah instead. Batteries that big don't come in 12V units, so now you're looking at 6V batteries or 2V cells. Best bang for buck here would be 8 x Trojan L16RE-B batteries (6V, 370Ah). That's going to set you back 50k just for the batteries.

I'd put 8 x 300Wp panels on that, probably Canadian Solar since they are fairly good quality and sell at a good price. You should be able to get that for around 20k. So you're at 70k, no inverter yet.

I would put a 3000VA Victron Multiplus on that, but I'm biased. It is a good inverter, in my opinion a better inverter than the Imeon, but the Imeon isn't a bad option... just don't use it close to the sea. It doesn't like moisture. Search on this forum for pictures of such an inverter that lived in a garage in Duynefontein. The Multi will cost you around 25k. Then you need MPPTs (because the Multi doesn't include one), that's around 9k for a nice big 150/70 (70 ampere model), so you're sort of at 100k, but you still have to buy cable and all the mounting materials. Thumbsuck, you might be able to do it for 130k, if you do most of the work yourself (but it comes with a much better inverter).

@Chris Hobson, am I being too optimistic?

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8 hours ago, plonkster said:

It is a good inverter, in my opinion a better inverter than the Imeon, but the Imeon isn't a bad option.

I would steer clear of an Imeon purely based on the discussion on this forum and the experiences of senior installers. It would seem they suffer from Sudden death syndrome and the backup service (not sure whether this is peculiar to South Africa) leaves a lot to be desired. To my mind an Axpert would be a better bet. Not that I would install an Axpert either (watch TTT choke on his morning coffee). There are so many option currently. Depending on budget and requirements I would look at Victron, Infinisolar or  Goodwe or any of the mjainstream GTI charger/inverter combinations.

9 hours ago, plonkster said:

That's going to set you back 50k just for the batteries.

We have had this discussion before and I am in the same position. Spending that sort of tom I would go Lithium.

 

9 hours ago, plonkster said:

.

@Chris Hobson, am I being too optimistic?

No Plonky I think you are close to correct. 

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Thanks Gents, noted. No Imeon as I've read the comments on the forum too. I like lithium, lighter smaller and not fussy. Great input plonkster and Chris, you guys are a huge help to this off-grid explorer!

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2 hours ago, Chris Hobson said:

not sure whether this is peculiar to South Africa

Had a chat with an Ausie and he indicated that Imeon do well over there. So I'm inclined to give them the benefit of the doubt and say it's a South African problem. I agree with you though (TTT would choke again), I'd put in an Axpert before I put in an Imeon... well technically that's not apples and apples... but I'd put in an Infini before I put in an Imeon.

2 hours ago, Chris Hobson said:

We have had this discussion before and I am in the same position. Spending that sort of tom I would go Lithium.

Agreed. I'd go with the pylontechs as they presently have extraordinary bang for buck. Keep an eye on BlueNova though, their new classic batteries look good and I have some fairly dependable info that it might drop below the 9k/kwh price point soon.

 

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i have finally logged in again...i have some time on my hands today......i will start reading all the posts, however if you sorted let me know else feel free to visit

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On 11/21/2017 at 10:01 PM, plonkster said:

You size the inverter for the peak load (your batteries needs to be big enough as well, of course), there isn't a direct relation between the energy required and the peak rating of the inverter. It is perfectly possible to consume 10kwh a day using a 500VA inverter... if it runs at almost full capacity all the time (0.5kw*24 = 12kwh). In other words, yes, assuming you don't have loads over 3kw, the 3.6kva unit should be sufficient.

To store 10kwh (or thereabouts) in lead acid batteries, you'll need at least 4 x 200Ah 12V batteries (48*200 = 9.6kwh). But lead acid batteries don't like to be taken down to zero, you want to keep them above 50% most of the time, so you will need double that. Parallel strings (ie 2 strings of 4 batteries each) don't work as well as one larger string, so I'd advise you to look at 400Ah instead. Batteries that big don't come in 12V units, so now you're looking at 6V batteries or 2V cells. Best bang for buck here would be 8 x Trojan L16RE-B batteries (6V, 370Ah). That's going to set you back 50k just for the batteries.

I'd put 8 x 300Wp panels on that, probably Canadian Solar since they are fairly good quality and sell at a good price. You should be able to get that for around 20k. So you're at 70k, no inverter yet.

I would put a 3000VA Victron Multiplus on that, but I'm biased. It is a good inverter, in my opinion a better inverter than the Imeon, but the Imeon isn't a bad option... just don't use it close to the sea. It doesn't like moisture. Search on this forum for pictures of such an inverter that lived in a garage in Duynefontein. The Multi will cost you around 25k. Then you need MPPTs (because the Multi doesn't include one), that's around 9k for a nice big 150/70 (70 ampere model), so you're sort of at 100k, but you still have to buy cable and all the mounting materials. Thumbsuck, you might be able to do it for 130k, if you do most of the work yourself (but it comes with a much better inverter).

@Chris Hobson, am I being too optimistic?

All good advise here. I concur with the battery recommendation. It's a very good battery for solar! I would only caution that 2.4kw in panels will not be sufficient to recharge a 10kw odd nightly discharge(i.e. 200amps @ 48v). To put back 200 amps odd, you will need at-least 4kw in panels as there are also day time loads that need to be supplied.

I feel good rule of thumb is 1000 watts for every 100 amp hours in storage (assuming a 48v system using lead acid based batteries)) i.e 400 amp hour battery bank odd, 4000 watts in panels. This is assuming your have sized the system for 30-50% DOD. Less DOD less panels. But, this is area and climate dependent. Costal areas have less sun that the Karoo as an example.

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