Bobster.

At 14:05 today, according to SEMS, my property was demanding ZERO watts. Which I find hard to believe. Surely the timer switches and the devices on standby (TVs and decoders) would draw something. OK... so the graph is smooth out. I get that. But it never shows me that zero watts were being consumed in the middle of the night.

Hi all, Here's a screen shot from the Goodwe SEMS portal The power flow diagram shows 3352.87 W coming from the PV panels. However the graph (which starts at midnight today) suggests that the panels have never once produced 3Kw. So... which data do I believe? If the lower diagram is correct then the graph is out, and vice versa. And if the graph is out then it's not much use for figuring out what my system does and when and trying to optimise use.

Nice. Thing is my system is under warranty AND I wouldn't know how to connect the extra. So can't do my own thing here. They've also been very helpful post install, so I would not want to cut them right out of things. But it looked like a chance to double up at a better than expected cost

I was keen to take advantage to double up on my batteries. But my installer says he spoke to Revov and they say the advertised price is erroneous. But surely... if they advertise it, they have to stick to it? OK... all they have to say is "stock has run out".

'Scientists at Rice University are taking a different approach — turning heat into light which can then be used to make electricity. They say their research could ultimately lead to solar panels that are 80% efficient. That would make panels that are four times more efficient than any commercially available panels today. " https://cleantechnica.com/2019/07/30/turning-heat-into-light-could-make-solar-panels-80-efficient-rice-researchers-say/

The unions are doing exactly what they should be doing - trying to keep their members employed. That's what they're there for and that's all they''ll do and we shouldn't expect anything else. I note that Gordhan has established a restructuring office. The real problem, of course, is that the numbers don't add up any more. Eskom is saddled with massive debt and the incremental bailing out is inevitable. Which means rising prices and taxes. And means that somebody is going to have to bite the bullet of addressing non-payment. COJ have done some disconnections of illegal supplies (not all in townships), but it's usually not very well received, and Eskom have much bigger, more geographically widespread problem than COJ.

I don't think so. The input voltage and current are stated separately. The 2000W/3200VA is stated as output.

That one I do know about.

Thanks all for all the info. I did realise during all the reading that my training was a little more up to date than 70s high school - IE I worked for what is not Telkom in the late 70s and then fixed computer power supplies in 1980. Clearly all that experience doesn't make me an engineer 🙂

These problems can indeed be local. We recently had a problem in my STREET (not suburb) with fluctuating volatage. Turned out to be a bad connection in the distribution box at the end of the street. In fact it the problem was confined to just one phase, so not even every house was affected.

What? Next I'll find out there's another 3 letters in the alphabet. Modern education, I tell you... Seriously, it did occur to me that my puzzlement might have something to do with all the electrical stuff I did at school being DC and not AC.

What's that when it's at home?

From high school science I recall that W = VA. (power = current * voltage) So why is the output of my old UPS rated at 3200 VA or 2000 W?

Well it seems OK to me (bar the recent loss) but I have nothing to compare it against. The only real test it's been put to was a 6 hour outage that affected half of my street (blown circuit breaker in the local substation). That started before the sun was up and ran to about 10:30. I didn't notice a thing.

Actually I think the problem does vary considerably with locality. Load shedding is load shedding, when Eskom do that, it affects everybody. But if you look at Johannesburg the last few months, when there has been no actual load shedding (I didn't say "no outages"), Blairgowrie has been pretty stable, whilst Linden, Emmarentia and Northcliff have had a lot of problems that are caused by the local infrastructure. Further south, Ennerdale has more than their fair share of problems because of illegal connections from a near by informal settlement.

Turns out it does. Revov sell a package of two batteries, BMS and cables.

PS: On the days when we ran just panels and inverter, our savings was in the 40% ball park. So that's not to be sneezed at. We would have protection against load shedding whilst there was strong sun light. I have two arrays of panels. One facing east, one facing north. I've a lovely, sunny patch of west facing roof. If I get the extra cash I'll put panels there too to get the most out the sun.

There seems to be some disagreement on definitions. My understanding is that "grid tied" means you have solar and inverter but no storage. I know that some web sites use the term to mean "retains connection to the grid". So, using my more narrow definition, you would have an inverter and solar panels generating extra power during the day. I think what @Fazil is thinking of is a HYBRID system, that has batteries for storage as well as solar cells for generation, and retains a connection to the grid. I have the latter. When there is no power it continues to produce output but Nothing is sent back to the grid Only the "backed up" circuits in my home get power. Effectively the DB board is split and there are non backed up circuits (eg Stove) which will not receive power whilst the grid is not available. For a couple of days, due to a problem with the inverter firmware, we ran as grid tied - solar supplementing the grid. I did test this by throwing my main circuit breaker during the day. What happened was that the solar power was still distributed to the backed up circuits.

The solar cells will drop in efficiency year on year, but only a couple of percent. So tell me, when did you last clean the panels? Or do they have 2 or 3 years of accumulated grime?

@Gerlach I'll check my invoice and get back to you. I've got 10kw/h of revov, and ISTR that was about 40 grand. The control box that sits atop of the batteries has no branding on it. I run out of knowledge at this point - does that come bundled with the batteries or not? Anyway... suddenly the batteries are back. Here's what I think happened. That "restart the batteries" option in EZ manager does work, but only when there's solar power available. The batteries restarted almost immediately the panels came up this morning. So it seems to have remembered that I made the request but executed it much later. The battery is now 100% and looking at the portal, everything seems to be working properly. Previous issues were because of the inverter not tracking SOC properly. That was fixed with a firmware upgrade. This latest is something different.

I didn't connect the batteries and haven't fiddled with the connections.I may have measured across one battery. Last night the battery dropped from an indicated 92% to nothing. This morning, with the solar coming up, it shows the batteries being charged but SOC is 0%. Might the battery pack be dodgy. And nothing will restart it. It refuses setup changes from EZ manager - including the option to restart the battery. The battery controller will not reset. I suspect the installers jump the battery to get it working. They usually arrive with a piece of heavy duty flex in hand. My first preference is that they get the system stable, My second is that they tell me how to restart it so that I don't have to wait a day at least to get it up and running again. Surely the Goodwe is not so badly designed that a lay person cannot restart it?

Thanks. So it's not 105 amps PER HOUR. So if my old system is fully loaded, it will provide about 1.8 kw for an hour. It used to see us through a load shed without much trouble, backing up a TV, two standard lamps, decoder, wifi and one fridge. It certainly had it's uses. It once went 18 hours with that loading, but the batteries were never the same after that

My old backup system has lead acid batteries, rated at 105 A/h. Why are batteries rated this way instead of W/h? Surely 105A * 12V gives 1260 W/h? And what does this mean? Can the battery deliver 12A/1260 W for an hour, and half of that for two hours? Would it not be less confusing for lay persons such as myself to rate batteries by power rather than current? Would that not make comparisons easier?

I recently had a similar inverter installed. At first it didn't track SOC properly, which led to a complete system failure at one point, as the inverter sometimes "thought" the batteries were charged when they weren't. What the inverter "saw" and the app reported was not the actual SOC of the batteries. The installer updated the firmware on the inverter, and now it tracks SOC far better. I'm using Li Ion batteries.

Ah... there you go. I have 10kw/h of battery. Usually goes down to 50/low 40s by the time the sun comes up, but that's with the heat pump kicking in at 4:30 and taking a big chunk of battery.