South Africa's rooftop solar explosion

I just replaced 2 x 250 watt Yangi panels fitted in 2015 with Canadian Solar 555 watt

The output in sunshine from the old panels (in series) was 72 volts and 5.5 amps. The new ones deliver 122 volts and 7.5 amps

Today there is 100% cloud in Cape Town. I am seeing 90 volts and 3.8 amps, so 342 watts

The new panels have a 25% larger surface area
 
Mike Hoxbig said:
If we didn't live in SA, with SA problems, they could add even more panels to the open parking and turn it into shaded parking...
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I happened to do a bit of Google Earth browsing today and found 3 malls that installed exactly that (note that I don't know these malls in-depth, so it might be on top of previously open rooftop parking):

Kolonnade
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The Grove
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Eastgate (this one is quite different)
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wingnut771 said:
Most?
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Yup most shopping complexes would be grid tied due to the cost of batteries for them, so they have the solar running to keep their costs down during the day, but they switch back at night. Be in a shopping center with solar panels during load shedding and see, the generators still kick in and a few of the smaller shops still go dark.
 
Lupus said:
Yup most shopping complexes would be grid tied due to the cost of batteries for them, so they have the solar running to keep their costs down during the day, but they switch back at night. Be in a shopping center with solar panels during load shedding and see, the generators still kick in and a few of the smaller shops still go dark.
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I would say 100% of shopping centres are grid-tied, not "most" but "all".
 
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Here is clearwater mall, massive solar array, it does seem to have some big batteries in the one parking lot, but they still fire up the generator when there is LS for one half of the building by the sounds of it. Plus when there is LS the lights are dim as hell.
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Randridge mall has had solar panels since at least 2019, last time I was there during LS in Jan they were running the generator, they are grid tied still.
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Relatively new install at Northgate, I've been there during a power failure (common in this area) everything was still running, generators are still on site not sure if they were running as they were on the opposite parking lot, some shops were dark though.
This PnP used to have solar panels, not sure why they removed them
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This little shopping center is mostly powered by solar, haven't heard a generator
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So it seems the bigger ones are still mostly grid tied where necessary, even the big Makros they don't have big battery banks but still have generators
 
wingnut771 said:
I would say 100% of shopping centres are grid-tied, not "most" but "all".
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Check my reply, smaller ones don't seem to be from personal experience, some seem to be half and half now as well. But by grid-tied I mean they require the heartbeat from Eskom to still have power coming in, not running a hybrid system
 
Lupus said:
Check my reply, smaller ones don't seem to be from personal experience, some seem to be half and half now as well. But by grid-tied I mean they require the heartbeat from Eskom to still have power coming in, not running a hybrid system
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Yeah, and they are not even allowed to feed back into the grid, hence the batteries.
 
wingnut771 said:
Yeah, and they are not even allowed to feed back into the grid, hence the batteries.
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Yup and that's why the "rooftop" explosion is a bit of a lie, as the residential side that at most uses 20% of demand cannot be 5GW shaved off Eskom as that would mean 70% of residential have gone solar. So therefore most of the solar would start to wane around 4pm?? So it honestly doesn't make a lot of difference and probably why we're only in reality seeing maybe 1 to 2GW off demand at peaks instead of the 5 touted.
 
Lupus said:
Yup and that's why the "rooftop" explosion is a bit of a lie, as the residential side that at most uses 20% of demand cannot be 5GW shaved off Eskom as that would mean 70% of residential have gone solar. So therefore most of the solar would start to wane around 4pm?? So it honestly doesn't make a lot of difference and probably why we're only in reality seeing maybe 1 to 2GW off demand at peaks instead of the 5 touted.
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Lets compare to last last year before loadshitting started.
 
Lupus said:
Remember most of those are grid tied
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Quite possible. Although even then they reduce daytime demand quite a bit.
Lupus said:
Check my reply, smaller ones don't seem to be from personal experience, some seem to be half and half now as well. But by grid-tied I mean they require the heartbeat from Eskom to still have power coming in, not running a hybrid system
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Depending on the mall size and PV system, they might have (1) no batteries with a generator cut-over, (2) enough batteries until the generator kicks in (basically a UPS), or (3) enough batteries to last a 2-4 hour loadshedding window (with or without a generator backup).

But unlike households, malls (and businesses) typically do not have enough batteries to go more than a few hours.
wingnut771 said:
Yeah, and they are not even allowed to feed back into the grid, hence the batteries.
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Considering their air conditioning, I doubt any of them have enough PV to feedback into the grid in any case. Batteries are mostly loadshedding backup, and often recharges from the grid to full charge asap.
 
G.A.S said:
Quite possible. Although even then they reduce daytime demand quite a bit.

Depending on the mall size and PV system, they might have (1) no batteries with a generator cut-over, (2) enough batteries until the generator kicks in (basically a UPS), or (3) enough batteries to last a 2-4 hour loadshedding window (with or without a generator backup).

But unlike households, malls (and businesses) typically do not have enough batteries to go more than a few hours.

Considering their air conditioning, I doubt any of them have enough PV to feedback into the grid in any case. Batteries are mostly loadshedding backup, and often recharges from the grid to full charge asap.
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I would assume the batteries are there to make full use of their PV production and reduce their leccy bill.
 
Lupus said:
Yup and that's why the "rooftop" explosion is a bit of a lie, as the residential side that at most uses 20% of demand cannot be 5GW shaved off Eskom as that would mean 70% of residential have gone solar. So therefore most of the solar would start to wane around 4pm?? So it honestly doesn't make a lot of difference and probably why we're only in reality seeing maybe 1 to 2GW off demand at peaks instead of the 5 touted.
Click to expand...
That's why I'm counting retail/malls and businesses as well -- they are all impacted by loadshedding (unlike large business with separate load curtailment rules).

But as you say, the thing is that 5GW solar ≠ 5GW base load. So even at noon you will hardly get 5GW out of SA PV, even though individual installations might add up to that (due to weather, not feeding excess into the grid, or another reason).
 
G.A.S said:
That's why I'm counting retail/malls and businesses as well -- they are all impacted by loadshedding (unlike large business with separate load curtailment rules).

But as you say, the thing is that 5GW solar ≠ 5GW base load. So even at noon you will hardly get 5GW out of SA PV, even though individual installations might add up to that (due to weather, not feeding excess into the grid, or another reason).
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Demand is 22GW at noon though.
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wingnut771 said:
I would assume the batteries are there to make full use of their PV production and reduce their leccy bill.
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The businesses I've seen detailed statistics or talked to, use their batteries exclusively for loadshedding backup as the batteries will only last 2-4 hours at full demand on a hot but cloudy day; the main reason for their installations were to save on diesel or noise (especially at night).

The way businesses electricity bills are made up doesn't give the same incentive to self-generate (especially overnight), as their consumption R/kW are mostly lower than households' (with the difference made up of fixed charges).
 
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