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Planning a new installation


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Hi to all of you.

I am planning a new installation for a house under construction and need some advice. Hopefully the guys with all the experience will offer some advice so that I can avoid the problems they encountered when starting out.

I am planning to split the new DB into two sections : 1 section permanently on grid  and a second section on Solar PV power. I do not intend to ever attempt  the SSEG route so power generated  will be for own consumption only to save on energy cost and be self sufficient (partly) when load shedding occurs. I will endeavor to install only  energy efficient appliances and lighting which will run off the solar energy. I have a couple of questions as to what components I should select within the following constraints: I had in mind a 5Kva inverter with 2.5kw lithium battery system and 3000w of PV panels. I have the luxury of matching the load ( will probably be less than 3kW) to the system and I figured a oversized inverter will be better. I plan to incorporate loadshedding into the DB as well to control the load to match the available supply.

1. The solar PV section will be off grid with battery backup as stated above . However I would like to have a  transfer switch (manual or automated) to connect this section to the grid in case of a solar PV system breakdown or if no solar power (battery or otherwise) ) are available.  I reckoned I could achieve this in two ways: 

Option 1: Use a manual transfer switch which provide total isolation.  (or maybe a automated transfer setup to do the same?)

Option 2: Use an  inverter which  intelligently switches between the two sources. (will this option still be  classified as "off grid" by the authorities - Mossel Bay municipality in particular? )

If I use an inverter,  how do I prevent energy feedback into the grid. Which  type of inverter should I choose to suit my application?

2. Selection of components ( brand independent)

What route would you suggest I take - multiple discreet components i.e. separate MPPT charge controller,  inverter, BMS etc. or an all-in solution ?

I must admit I am a bit confused by all the  kits offered on the web where the systems sometime comprise of only an  "all-in-one" inverter ( eg. Axpert )  and sometimes they add an array of components to it as well.

2. Brand of components.

I know I am  treading dangerously now but I would like to have your input with regards to less expensive inverter options like Axpert vs Victron vs Goodwe vs whatever. Obviously I am on a budget here and am trying to get the most cost effective system,  but I do not want to regret going for the cheapest option later on.

Any advice will be highly appreciated!

Thanks

 

 

 

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22 minutes ago, Squonk said:

... options like Axpert vs Victron vs Goodwe vs whatever.
... Mossel Bay municipality ...

Welcome Squonk!

My 2 cents:
- Ccheck you municipal regulation, or pending regulations, let that guide you ito what inverter. You do not want to do a thing now and while from now, have to spend more to get it registered.
- If you have regular power failures, then get batteries.
- If not, are there consumers during the day to use the solar power?
- If not, don't do it. :-)

Why? Batteries are more expensive than Eskom, and most of the power usage is at night, if people are not at home.

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Thanks for the welcoming words, I look forward to hearing your advice.

With regards to daytime occupancy: I have a home office so am at home all day. We are 4 adults  at home all day (  of which two are elderly pensioners).

So I am hoping the the PV panels will carry the base load with the batteries covering the  supply drops during cloud cover etc.

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3 minutes ago, Squonk said:

We are 4 adults  at home all day (  of which two are elderly pensioners).

Excellent ... sorted. We are the same.

All that is left, are you going to do it according to regulations, or tell them to take a hike? It impacts on the best solution.

Edited by Guest
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It a new installation into a new house as I mentioned, so I would like to stay legal. That is why I would like to keep the system classified as "off grid" and avoid all the "grid tied" regulations. The only time I will switch to grid on the solar powered section is if I have no alternative power available.Only if  I switch over via the transfer switch will the whole electrical installation be on the grid.  The PV section will then still be isolated from the rest. If I have PV power available I will switch back and that section will then be "off grid"

 

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34 minutes ago, Squonk said:

That is why I would like to keep the system classified as "off grid" and avoid all the "grid tied" regulations.

My last few months research, you have a new house so you can avert the additional cost, is that grid tied for me is cheaper than off grid after 7 years.

Grid tied is more cost effective by a big margin. Look at Solis inverters also.

So, if you have the chance now, put in the DB and circuits from day one for off-grid, like 2 plugs in each socket, one red one blue, to show Eskom and inverter power.

And have the 2 DB's. 

That is what I would have done if I can re-do it all.

See the discussions here for what is coming: Is your system legal

and here Constitutional for more information.

If you follow them rules from CoCT, your should be good and clear, versus a huge shock later.

Then go and buy a Victron Multigrid ... talk to me, I know some people who have connections. :D

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2 hours ago, Squonk said:

So I am hoping the the PV panels will carry the base load with the batteries covering the  supply drops during cloud cover etc.

Look at Victron's ESS system. That's precisely how it works. It attempts to keep grid use at zero, and at times when the load is higher or there is insufficient solar the battery carries the load.

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Plan!

  1.  Dedicated solar room preferably on the southern side of the house.
  2. Enough nice thick conduit in the walls 32mm + (at the DB).
  3. 2 DBs
  4. TTT suggestion of have two plugs is a good idea.
  5. Lay out of your conduit (I cannot stand that people plaster a home and then the electrician comes and cuts channels for conduit. Electrician before the plasterer.
  6. Think about conduit for your PV. It is easier to lay once the trusses are up and before the roof goes on.
  7. Put in more plugs than you think you'll need.
  8. Perhaps plan to be able to implement home automation. Some of the light switches require a neutral.
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Thanks for the advice, guys. I think I must first go and see the municipality to get all the applicable regulations & procedures. Once I have that I will have to do some more research based on your advice given. I will report back periodically as things progress.

11 hours ago, Chris Hobson said:

Plan!

Thanks for the practical tips - a lot of good ideas there.

11 hours ago, plonkster said:

Look at Victron's ESS system. That's precisely how it works. It attempts to keep grid use at zero, and at times when the load is higher or there is insufficient solar the battery carries the load.

Had a quick look at it and it seems suitable for my application.  Looks pretty complicated though,  so I need to do a lot of research there.:o

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22 minutes ago, Squonk said:

Had a quick look at it and it seems suitable for my application.  Looks pretty complicated though,  so I need to do a lot of research there

If this features in your future, talk to us, let us help find you the right prices for Victron equipment. The PowerForum Store must also get onboard. @Energy you are reading this? :-)

I have had now one day too many of Axperts (off grid only) versus Victron (grid tied and approved) that has ESS to save you money on batteries, AND they can be bought at good prices.

We all are here to help.

 

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Just a quick report back:

I got the SSEG application forms and Tariff structure from Mossel Bay Municipality. Turns out their strategy is very similar to CoC .... to  make it completely unprofitable to go grid tied. They have a basic fixed network charge of R308 /month and energy consumption charge of R1.44 per kWh.  The energy feed in rate is R0.44 /kWh. The maximum  inverter size for a 60A  grid connection is 3.5 kVA.

So, and please correct me if I am wrong, you will have to feed in 700 kWh/month   (22,5 kWh /day)  to offset the basic network charge. Problem is with a maximum allowed 3.75 kVA inverter system you will never achieve that, even if you have zero self consumption. I do not understand the logic behind  the tariff structure at all unless it is designed to discourage grid tied domestic installations.

I will therefore go the "partly off grid" route. Split the DB and have one section "on grid" and the other section "off grid" (with the option to switch over to grid as the need arises). THe generation side will remain isolated from the grid to keep the authorities happy.

At  least I will be able to put in a > 3.5 kVA inverter to provide sufficient kWh.  I would like to have a system capable of generating  about 10 kWh / day

I will appreciate your advice regarding the topology of such a system. I have listed two possible topologies :

1.  PV Panels  -  separate MPPT  -  Pylontech Batteries -  Inverter.

2.   PV Panels  -  combined  Inverter MPPT   (Axpert?)  -  Pylontech Batteries   - similar to your system ?  @Chris Hobson

Do I need an additional Battery Management device or will the Pylontech  BM system be sufficient?

 

 

 

 

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26 minutes ago, Squonk said:

Turns out their strategy is very similar to CoC ...

Is there a part that talks about Self Consumption requiring a Pay as You Go meter?
Versus
Feed back with a fixed network charge of R308 ... etc requiring a bidirectional meter to be installed?

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4 minutes ago, Squonk said:

 The maximum  inverter size for a 60A  grid connection is 3.5 kVA.

First decision is whether you are going grid-tie or hybrid? I have purposely left off-grid off the list as the most popular off grid system namely the Axpert. I cannot recommend an Axpert to anyone who is going to connect to either municipal or Eskom supply. I have two Axperts that I would not part with but I am wholly off-grid and they suit 98% of my needs and when I add 1500W of panels I will be able to run the house and workshops off solar.

8 minutes ago, Squonk said:

I will therefore go the "partly off grid" route.

Go hybrid and then all your bases are covered. You will split your DB into essential and non-essential loads and still be able to power the non-essential loads with solar if there is more energy being generated than the essential loads can consume. This option makes sense to me an if I found myself in an urban environment this is the way I would go.

15 minutes ago, Squonk said:

At  least I will be able to put in a > 3.5 kVA inverter to provide sufficient kWh.  I would like to have a system capable of generating  about 10 kWh / day

There are several hybrid inverters that could easily generate 10kWh/day.  3kW of panels could do that easily. In fact except in really shitty weather 2.5 kW PV would be sufficient.

19 minutes ago, Squonk said:

1.  PV Panels  -  separate MPPT  -  Pylontech Batteries -  Inverter.

2.   PV Panels  -  combined  Inverter MPPT   (Axpert?)  -  Pylontech Batteries   - similar to your system ?  @Chris Hobson

Do I need an additional Battery Management device or will the Pylontech  BM system be sufficient?

If I was in your shoes I would choose between a Goodwe 3.6kW, an Infinisolar 3.6kW and a Victron  Multigrid. The Infinisolar is the cheapest of the three and has a versatile setup that should cover your needs (has a 2 year warranty). The Goodwe is mid-priced it setup is Plug and Play with you setting the inverter up using an app on your cellphone. Both the Goodwe and the Victron  have a 5 year warranty. The Victron is marginally more expensive but with it you have access to Victron's ESS which means you can fine tune your system tailoring it to your exact needs.

All three systems are approved to be partnered with Pylontechs. The Goodwe and Victron  inverters communicate with the Pylontech BMS. The Infinisolar does not but that would not be to my mind a major consideration. Integration of the BMS helps with end of charge and signalling back to grid and other niceties. The Pylontech's BMS is robust and hence it ability to operate in a stand-alone mode.

 

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27 minutes ago, Squonk said:

fixed network charge of R308 /month and energy consumption charge of R1.44 per kWh

That's better than Cape Town. Ours is R400 standing fee and R1.38 per kwh. They do however buy back at 85 cents.

You are allowed to fit a grid limiter and remain on your current tariff. You are half-likely to be moved to Home-tariff though, also has a small connection fee (about R150 I think). In the end it all evens out, or did last time I looked. If you buy 600kwh of energy it costs just about the same no matter what tariff you're on.

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11 minutes ago, The Terrible Triplett said:

Is there a part that talks about Self Consumption requiring a Pay as You Go meter?
Versus
Feed back with a fixed network charge of R308 ... etc requiring a bidirectional meter to be installed?

No, you  have to install a bi-directional split meter (credit meter) if you want to go grid tied with the option to feed in . Other wise if you go grid tied without the option to feed in you can keep the prepaid meter but you have to install  a "Reverse Power Blocking" device

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1 minute ago, Squonk said:

Other wise if you go grid tied without the option to feed in you can keep the prepaid meter but you have to install  a "Reverse Power Blocking" device

So you can go grid tied, for with any good grid tied inverter, they have the  "Reverse Power Blocking" in place or you can get it extra.

I'm going this route, Self Consumption with PAYG meter, with a Multigrid.

Also see what Plonkster said, as he has a point. I just don't want to be bothered with an additional R8k costs for that bidirectional meter. Not sure what Mosselbay charges.

 

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15 minutes ago, Chris Hobson said:

Go hybrid and then all your bases are covered. You will split your DB into essential and non-essential loads and still be able to power the non-essential loads with solar if there is more energy being generated than the essential loads can consume. This option makes sense to me an if I found myself in an urban environment this is the way I would go.

That means connecting the inverter directly to the grid and  I will have to  go through all the onerous and costly  procedures to comply with Mun regulations. 4 quadrant meter, professional engineer sign off and commissioning report etc.  I am not sure whether that  is worth it if I cannot generate enough kWh to feed in to offset the expenditure

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10 minutes ago, The Terrible Triplett said:

So you can go grid tied, for with any good grid tied inverter, they have the  "Reverse Power Blocking" in place or you can get it extra.

From what I can gather they do not accept "built -in software selectable reverse power blocking"  They do not even have any Victron equipment on their Approved List!

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4 minutes ago, Squonk said:

They do not even have any Victron equipment on their Approved List!

Mmm, Victron, all the products, is on the CoCT list. Multiplus and Multigrid as is on and the rest just needs a Ziehl, also on the list.

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32 minutes ago, Chris Hobson said:

First decision is whether you are going grid-tie or hybrid? I have purposely left off-grid off the list as the most popular off grid system namely the Axpert. I cannot recommend an Axpert to anyone who is going to connect to either municipal or Eskom supply. I

I plan to have the  PV supplied section of the DB completely "off grid" . If  I have no PV or battery power available I will manually switch over to grid completely isolating the inverter etc. That way I can at least install  a 5 kVA inverter  system.  If I go grid tied they limit you to 3.5 kVA.  I suppose I can automate the "switch-over"  at a later stage.

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Just now, Squonk said:

I plan to have the  PV supplied section of the DB completely "off grid" . If  I have no PV or battery power available I will manually switch over to grid completely isolating the inverter etc. That way I can at least install  a 5 kVA inverter  system.  If I go grid tied they limit you to 3.5 kVA.  I suppose I can automate the "switch-over"  at a later stage.

If you match your equipment better you do not need an MPPT and two db's and and and then you will see the grid tie works better and ...

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21 minutes ago, Squonk said:

I suppose I can automate the "switch-over"  at a later stage.

I have been off-grid since 2012 using the BMV's relay to swap based on SOC between grid and off grid ... there are issues like the break. Got tired of the "wastages" too, as I have to wait for the SOC to be reached before it switches.

So I agree with Erastus, grid tied works much better, more savings etc.

BUT not at the cost of stricter regulations than say CoCT, or more costs no. Like Pilotfish is facing in JHB. That is not on. 

So, to automate it, the break requires a UPS:
1) not all UPS can be fed by another inverter - check this!
2) commonly used UPS'es are modified or even square wave which means your equipment does not run on pure sine wave anymore, when the switch takes place.

Old toppie who does generators told me way back that switching regularly between say pure sine wave to modified or worse, square wave and back, is not good for electronic equipment.

So I used online UPS'es that run 24/7/365 off batteries to mitigate the above two issue as the equipment is always fed a clean sine wave, safer than Eskom.

Used 2nd hand APC UPS'es. Biggest one was 2400VA.

Edited by Guest
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Throwing equipment and money at a problem is the government way.

Simplification is less expensive.

Unless you want to say " look at my system " it cost me R130K and R90K wasted electronics.

The most important is to use a well match system. Then you do not need expensive equipment that gets sold to you and the only benefit is the commission to the sales rep.
I do not have MPPT and what many people are referring to.
I simply have batteries inverter solar panels.
The little controller I developed my self and it  has a few relays and are doing some control of my house.
If you want to be smart split the electricity in two two ares:
1 12/24V for lights and LED lights. Use a fat battery and you have emergency lights. a Small charger Power supply and you can keep the bat running at night. So you do not need plenty heavy stuff.
Never forget that grid tie means the grid is a endless battery.
Once you get your mind to understand that then you will understand you do not need massive batt banks
Electricity is going to get rough in time to come.  Charging your battery during the day is feeding into the grid. It is maintenance free and cost free.

Never use KWh when calculation solar effectiveness. A solar panel does not produce Kw it produces amps. In some cases a 350W solar panel is worse than a proper balanced system running a 250 / 260 W panel.
I bought 6 second hand PV's because some one decided that 350W is better than 260W.  The reality is that a panel can only give x amps.
Design your system re that way and you smile all the way.
Use MPPT and what ever and that is money down the drain.
All transformers and added stuff has a loss no matter how good they are.  Some 5 some 18%. The manufacturers hide that. 350W - 18% =  287W.  Then you wastes R5 per watt and paid for a useless MPPT.

If you have 48V system and panels greater than 270W you have feed a sales rep.

You can simply start with a grid tied system and charge that battery the way you charge your fancy batteries. In batteries you need one cell of many to fail and you have a problem.
I was forced of the grid CoCT wrongly cut my electricity and water so I had to go off grid.
Now I am replacing my 3Kw inverter with grid tied inverter. Got permission to install 10Kva SSEG.
But 10KVA is not the way one has to think. If I CHARGE the grid I can discharge 3 months later at a lesser fee than a battery.
Therefore the way I think it is
1stly I save R3500 city power 2ndly I do not have to pay rates and taxes.  Therefore you get R5K back per month. Batteries can not beat that.
If you are worried about a power outage.
Simple a bigger than normal lawnmower engine from Talisman +/- R3000 a second hand 100amp alternator from scrap yard. a pulley or 2 an you have a nice 5Kwatt generator.

P = I X E   50V X 100A = 5000W

See the grid as a battery and you will hardly ever have replace a single cell that caused a failure

In my case I can sell 10Kva and store power for a rainy day. Is +/- a few K PLUS R3500 I had to pay electricity and that is the changer.

A battery means to throw $ in a bottomless pit.
Even F1 with best battery packs have plenty failures.
 

Edited by Erastus
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