Some impressive figures there. I take it your panels are south facing?
We have 11 facing ESE and 5 facing WNW. We do live in the sunniest part of the UK though.
My 16 are split too, but 11 ESE and 5 SSW? In Kent.Never had more that 990 in a month though.
We have only had our Solar panels since late December, so I can’t compare previous years. We have 15 panels (455 W), with 11 due South and 4 split equally E/W.
Here in the NE UK May was our best month with 968.9 kWh generated. June delivered 960.6 kWh, so very close, but July is much lower due to a lot more rain and cloud at 777.9 kWh by today.
We export our excess Solar - pretty much all of it - each day. Our battery charges overnight (24:00 to 07:00) and stores almost enough to get us through the rest of the day.
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Upto 24 July things were looking good but then the inverter stopped working. I had exported 756kWh and the panels provided over 600kWhp. Zilch since:worried:
The upside is that the inverter should be a SolarEdge Home Hub rather than the HD Wave. This supports the Backup interface for working off grid. Might be several weeks of waiting though.
Phil
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That’s the key. Export what you don’t need, and fill a battery when it is cheap.
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Indeed, whilst tariffs like Eon NextDrive and Octopus Go together with flat export rates etc are around - although these might not continue as the UK gets more Solar capacity.
As a last hurrah we’ve had a good couple of days, finishing with a total of 811 kWh generated. So not as good as April, May or June, but we still are up on estimates for July.
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We had a torrential downpour yesterday in the early afternoon, so production wasn’t great, but we got to 990kWh for July. A few more kWh would have been nice, but a thorough watering of the garden was so much better.
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I’ve noticed a few people mentioning problems with Octopus not showing all of the daily readings in the app. I don’t have solar, but I have noticed the same problem and emailing them doesn’t seem to help.
They do get things sorted out eventually, but if you are anxious then a good way to check is to use the Octo-Aid app. This is a third party app which uses Octopus’s own data but allows you to do all sorts of things that Octopus don’t bother with. Even without trying to do any of that, you can see the data long before it shows up in Octopus’ app, hours before in fact. And if Octo-Aid has it, then they got it from Octopus, regardless of whether Octopus is showing it in their own app.
If Octo-Aid doesn’t have it, then it means Octopus doesn’t either and that is worth sitting on a phone to Octopus about (although the last time I started noticing no readings in the app for several days, it turned out that the O2 network was down locally and it all started working again after that network locally came back on line).
I used to find gaps in mu export dara from octopus. Or more likely from the data provider to octopus. This sometimes happened with my import too, meaning they charged me at the standard rate ratherbthan E7, whichni was on at the time.
I got them to atrach to my bills the plot of what is used and when. Nice little graph showing each 30 minute slot each day of the month.
Fixed my issue with them. But, there is a day or two delay each month when they bill me. Odd, but my gas and electricity export " bill" comes 2 days before the real import bill. They told me this extra data takes time.
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Yesterday after 27 days with a faulty inverter the new one was fitted. This morning I was able to control the battery to charge from and discharge to the grid.
Probably cost about £150 in higher cost imports and lost exports 
. The upside is that I have an inverter compatible with the backup interface allowing me to be off grid. I could also build in some redundancy with a follower inverter. I’m told the manufacturer changed its ERP system affecting business logistics for parts. Hopefully the delays will be shorter if it happens again.
Phil
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That’s excellent news, and hopefully it will give many years of good service.
I was talking to our installer the other day, and explaining about how we were dumping the battery during the evening and then refilling in the early hours. He told me that this would significantly reduce the life of the batteries, possibly even halving it. As the two batteries cost £4,000, it may well be the case that it’s best not to dump power and instead maximise battery life.
So for now I’ve stopped dumping the batteries. As we get into shorter days there will be less power available to dump anyway. We are going to stay on Intelligent Octopus Go in the winter, rather than switching back to Cosy. Hopefully the batteries and solar will get us through much of the day, and that we won’t need to use too much 28p power in the evening. Once we know that we can do the maths on whether a third battery makes economic sense.
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What make of batteries?
We have a Tesla PW3 which has a 10 year guarantee and unlimited cycles. That said we charge overnight and almost completely run the house for the rest of the day on the battery. It needs ~1-2 kWh of Solar or peak grid, so ideally it would have a slightly greater capacity. We export any excess Solar to the grid.
If I’ve understood correctly, you are using cheap rate power to charge batteries so that you can use that power to avoid using expensive mains power at peak times. Is the installer saying that the problem is due to rapid charging from the mains as opposed to slower charging from PV through the day? If so, I don’t quite understand what you mean by “As we get into shorter days there will be less power available to dump” as surely that would only be the case if you were charging from PV.
I’ve probably missed something here! Just looking at adding batteries to our existing PV and heat pump setup and trying to do some meaningful calcs.
Ah, it made sense to me!!
We fill the batteries overnight at 7p. At the moment they stay full all day, as the solar is more than enough to run the house. So I’ve been dumping from 7pm to 11pm, lowering the batteries to 20%. We then fill up again from 11.30pm, ready for the next day.
When we get to winter, the batteries will fill overnight and run down during the day, partially offset by what solar there is. So by the evening there will be little if any left to dump. The heat pump and electric cooking means we use more electricity than if these were gas.
I’ve been looking at the performance warranty of the LuxPower batteries. It guarantees that they will retain 70% efficiency for 6,000 cycles or 10 years, whichever comes first. It’s clearly a fine line, and I’m really not sure what to do for the best. If we don’t dump, the batteries will stay between 90% and 100% full for at least half the year, so on balance maybe we should turn the dumping back on. They will dump in the winter anyway, running the house, so doing the dumping in the summer will just make it like dumping all year.
Does that make sense? I’m happy to be advised!!
Why don’t you export the solar and run the house on the batteries?
Ah, so dumping is exporting rather than using battery power?
Most of our solar is exported, with the rest running the house and topping up any of the battery that we use, eg when boiling the kettle when there isn’t enough solar.
Yes. So we’ve been getting to 7pm with the batteries full. We then export from the batteries for four hours, running them down to about 20%. We then refill the batteries from the grid at 11.30pm. All the export is paid at 15p, and it then costs 7p to refill. So if we export say 10kWh in the evening and replace the power later, we make 80p a day, or £24 a month, except in winter of course. The question is whether the £24 for say six months, so £150 a year, is worth the shortening of the life of the batteries. Or maybe the batteries will lose efficiency over time regardless, meaning that we may as well carry on exporting in the evening. I’m confused. 