sorry, the regulation is 25%, not 15%
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A new solar installer came past and saw my 50a double pole breaker for the inverter and asked: How did that get approved?
Apparently, he said, they have to fit a 25a(?) breaker as per âregulationsâ, exactly for this battery charging thing.
Me, I just pulled up my shoulders and said: MultiPlus-II 48 5000 70-50 is the inverter specs, so thatâs what I did.
The battery charge current limit is 25% of your main breaker size, so for a 60A supply that is 15A. You do not need to limit it with a breaker though, since that would cripple your passthrough.
The exact wording in the CoCT âRequirements for SSEGâ document is:
Maximum Battery Charging Current Limit is 25% of the circuit breaker size of the
customerâs service connection, as per Table 1. This limit must be specified on
the inverterâs serial-plate or if software adjustable, the setting must be password
protected.
I go the password-protected, software adjustable route.
So 25*230/50 about, or 115A. Since the 5kVA can only charge at max 70A, youâre hardware is already within the required range.
Itâs 25% of your main breaker size, not a fixed 25A, but your point stands: With a 5kVA MP2 thereâs no need to worry about CoCTâs charge current limit, since the inverter cannot exceed it.
Oh! Of course. Well, letâs do that math again then. For someone with a 60A breaker (most of us on single phase connections), thatâs 15A then, times 230V, divide by 50-ish. Thatâs 69A. Multi can do max 70A (and it derates pretty quickly anyway), so youâre still completely safe.
And then the penny dropped ⌠the solar installer was installing bigger inverters, 8kva, and bigger their main market.
Many people staying in estates have three phase power. Then the total incoming current is at least 120A if I recall correctly.
The limit is 25% per phase, so if you have a three phase supply and a single phase inverter then youâre still limited to 25% of the main breaker size. However, if youâre lucky enough to be able to afford a three phase inverter/charger then youâre effectively allowed a maximum charging current of 3 x 25% = 75% of the main breaker size.
Well, actually, it is still 3 x 25%, as you have to have a 3-phase generation. You donât get to put it all on a single phase.
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I donât see that the inverter capacity is limited in that way, only the generation to the grid.
This is now updated regs, but in the old regs, the inverter size was the limitation on single phase, not on three phase. These days they have clarified.
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And that reminded me again of why I would rather install 'n Solis Grid Tied inverter for earning from CoCT, than bother with my main system to feedback, because of the Max Generation Capacity.
Better bang for buck too. The efficiency of an AC-coupled system is such that if your goal is to generate excess energy to sell, thatâs definitely the way to go!
I was referring to the maximum charge current - the last column.
This wasnât part of the old regs though.
Ah yes, CoCT splitting up the limits into generation, charging and export was a major step forward. Initially they didnât allow you to have more than 3.5kWp of solar panels on your roof if you had a 1P 60A supply. That was depressing.
When I installed my system the regulations seemed to be in flux and installers werenât sure what they were allowed to install and what not. I got a lot of conflicting information, and the documentation on CoCTs website was quite outdated at that stage which didnât help. I got my system signed off, but itâs not what I would have installed if the current regulations were in place back then.
If you pay for a 60A supply, you can use a 60A supply.
For a soup kitchen, growing marijuana in the ceiling or charging batteries.
Any other interpretation of regulations is wrong. An electronâs energy is indifferent to how itâs used.
A solar battery charger is just a load and no different from the case for charging a fleet of golf carts. ( Which you are entirely entitled to do if you pay for it).
There is a rationale behind regulations.
If you are using 100% of your supply ( to which you are entitled) plus 25% that you make on your PV inverter ( to which you are also entitled).
And then the grid is lost. You have 125% of unfed loads on a 100% capable system. So when the grid returns, the system has to deal with a 25% overload until the delayed generation from the PV inverter is available.
It is deemed this level of temporary overload is OK, but no more.
Largely a first-world problem.
That limit on panels back then, was for like GoodWE, when the inverter could not be programmed to 3.5kVA max if memory serves.
Most of us âolderâ (forum that is) members had to go through that right at the start, hence I had to install a 3kva MPII ⌠then the regs changed, no feeding back then one can go much bigger. So now I have a 5kva ⌠and no feeding back.
Upon further contemplation, if I do go the Solis route, I still have the issue of the 3.5kVA limit when grid-tied and feeding back ⌠that limit complicates everything if the main system, also grid-tied, runs.
So yeah, this feeding back thing does not âfeel likeâ my kettle of fish. If CoCT comes and begs me for some watts, then we can discuss it some more. Till then, I do me, they do them. 
The massive charge for the bidirectional meter means it will never be economically viable for me. But even I was feeling very generous, wanting to help out my fellow man and all, and I decided to cough up for the meter then the next thing thing that reallty sticks in my craw is the monthly meter reading / service charge. Excuse me, I am the one providing the service here.
And right there, we hit a nerve.
You cannot âprovide that serviceâ unless an entire infrastructure is in place for you to do that.
Who pays for that?
See, way back I was in contact with CoCT officials and said the exact same thing to them.
They replied, and it made perfect sense. Any business has a cost-to-do-business component. If we sell to like say Cpt, the more âfriendly cityâ, there is the cost of that infrastructure. Yes, we now pay a fixed fee, but there still is the new cost to do the accounts. Who pays that cost?
Either we pay that as a fee or they pay us less per kW, but someone is going to cover that cost. It can be automated/computerized, no humans reading meters, again, who is going to pay that cost for the systems development running into millions, the then new meters that can interface, the staff to run it?
I realized, as homeowners, we have to start thinking like business people when selling power back.
Things like:
VAT, we are not VAT vendors. So we âloseâ on that.
It is an income, so then there is the SARS implication on that taxable income.
Then we have to consider the depreciation, and the tax implications on that, if any, on the equipment purchased, if applicable to us homies.
Then the biggy, the earlier replacement costs of the equipment running âflat outâ 365 days of the year.
Once one sits down and do the financial planning around it all, the âbusiness planâ if you want, is it still a viable âinvestment/income generatorâ?
No, it is not.
The scale to make a profit for us homies, our systems are way too small, read, too âexpensiveâ to make a profit on.
Iâm happy to be corrected.
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