Solar panels and battery - any real world reccomendations?

HungryHippos said:
Gut feeling is not sure why you've got a 3.6kw inverter paired with 6.1kwp of panels, this has come up before here, but it seems most installers try and install the smaller inverter because it makes their lives easier.

Has anyone seen Octopus are now installing solar?

octopus.energy

Octopus Home Solar and Battery Storage Installation FAQs

octopus.energy octopus.energy

It looks like it's a Givenergy system based on the battery spec they've put in the FAQ with the sizes.
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I have 2 inverters installed which I now understand why - though I sort of wonder if a higher capacity inverter would have been better?
 
Vaddoc said:
Honestly, although this is the norm at this time, I think it is expensive. With twice the amount of batteries and a larger inverter, it would be ok. Now Tier 1 means nothing, could be low quality panels produced by a very healthy financially company. Personally I ve decided to delay pulling the trigger until this mess clears.
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Expensive compared to what else is available at this time or just too expensive in general for you to pull the trigger?

We've been sleeping on the idea for a number of years, but having just moved house to somewhere we know we're staying for many years, it seems the sooner we get solar the sooner it pays for itself.

HungryHippos said:
Gut feeling is not sure why you've got a 3.6kw inverter paired with 6.1kwp of panels, this has come up before here, but it seems most installers try and install the smaller inverter because it makes their lives easier.

Has anyone seen Octopus are now installing solar?

octopus.energy

Octopus Home Solar and Battery Storage Installation FAQs

octopus.energy octopus.energy

It looks like it's a Givenergy system based on the battery spec they've put in the FAQ with the sizes.
Click to expand...

My understanding of that is because it is very unlikely we'd ever see 6.1kW being produced at any given time. Also, that's 3.6kw of AC output, given the installation would have 2 batteries, any excess power from the panels during the day that we aren't using would be stored in the battery.
I may well be wrong though...

It's a Lux pure sine wave hybrid inverter, and Greenlinx batteries.
The PVs are 20.5 % efficient. Not sure on the brand though
 
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Do inverters suffer from being run at >100% of their capacity?

I specifically over-specced my micro inverters (I appreciate slightly different scenario) so that the electrics weren't ever being overworked.
 
Freefaller said:
I have 2 inverters installed which I now understand why - though I sort of wonder if a higher capacity inverter would have been better?
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I don't really know, maybe there is a reason for it!

If you have two batteries then throughput is per inverter so that would be a good one.

Otherwise think you can only connect so many strings to one inverter, seems 2 strings each, so that would be another.

With the GE inverters I'd sort of assume they may fight eachother without some central control thing, but some people say they work fine together kind of independently.
 
I've just spoken to the supplier of the quote with a 6.1kW pv system and a 3.6kW inverter.
They say because the panels are split over SW and SE, we'd never produce 6.1kW at any 1 time, but we'd get the production from earlier in the day and later into the evening.


They do offer 4/5/6kw inverters, and haven't tried to sell me one so I dare say the 3.6 is actually sized correctly.
 
What's the price difference? If it's a couple of hundred, I'd go for bigger one. I've got SW,S,SE panels, and during the height of summer last year I was producing more than my panels quoted capacities.

I expect the reason to use a 3.6 is more to do with not having to wait for DNO approval.
 
You can often limit the export on them to 3.6 even on the bigger ones, it just means you have options later and it can process more than 3.6kw at once for house load + battery charging.
 
HungryHippos said:
I don't really know, maybe there is a reason for it!

If you have two batteries then throughput is per inverter so that would be a good one.

Otherwise think you can only connect so many strings to one inverter, seems 2 strings each, so that would be another.

With the GE inverters I'd sort of assume they may fight eachother without some central control thing, but some people say they work fine together kind of independently.
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A second battery is definitely on the cards in the future. I think for me it was to maximise peak power which suits me fine.
 
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Mercenary Keyboard Warrior said:
Its not even drawing close to 11kwh, thats the point, so its not keeping it, its never charging it.
I expect losses, they quote 95% round trip efficiency, which would broadly seem to be around the level that I am seeing.
Winter isn't the time for solar to shine its the time for batteries to shine by charging them with cheap off peak units and using them during the day.

I didnt mention it above but I specifically queried batteries since I read the spec on the first version they were going to supply (it changed later) specifically said they shouldnt go below 0 celcius. I pointed out that happens a lot in the UK and was told its not a problem
At no point did the installer say its not a problem but the specs wont be what we are quoting, or its not a problem, but they wont work for days on end if you get a cold snap.
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I can tell my system to charge through the app, it will say it is, but never does. I have to control it through the web interface to get acurate results. Have you got installer access to your system? It does sound like something isn't setup right. Have you tried a force charge via the inverter? Hopefully if you can get it to 100% via an inverter force charge, it will recalibrate itself. Although it does sound like a BMS/setup issue. Is there any firmware updates for your system?

 
Bug One said:
What's the price difference? If it's a couple of hundred, I'd go for bigger one. I've got SW,S,SE panels, and during the height of summer last year I was producing more than my panels quoted capacities.

I expect the reason to use a 3.6 is more to do with not having to wait for DNO approval.
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DNO approval, is for a PV array over 6.2kW. Not inverter capacity related apparently.

We've just had another guy round.
7.2kW panels
3.6kW Sunsynk inverter
5.12kW/hrs Sunsynk battery

£14.6k
 
casper_uk said:
I can tell my system to charge through the app, it will say it is, but never does. I have to control it through the web interface to get acurate results. Have you got installer access to your system? It does sound like something isn't setup right. Have you tried a force charge via the inverter? Hopefully if you can get it to 100% via an inverter force charge, it will recalibrate itself. Although it does sound like a BMS/setup issue. Is there any firmware updates for your system?

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Thanks for the link. I may give that a try, Thurs/Fri when I am next at home in the morning. Battery will be only down around 20% at that point so should top up pretty quickly.
Yes installer has access and they have looked.
I agree on setup and thats been my issue, I ask is everything ok they say yes. But it really feels like no its not.
I dont think I said but its 4 batteries, 3.1each (4x = 12.3 due to rounding) the output for 3 battery system.... 8.4kwh which is basically what I am getting, but they won't entertain that maybe 1 battery is recognised but isn't charging.
Certainly the system recognises all 4, in fact it shows 8 which I believe is that each battery is two halves, hence the high charging rate (they spec 1 hour for a battery, but 4 is above the inverter cap of 5.5kwh)

App, web, both when charging to full get SoC to 100%, but the reality is its not 100% since its never drawing enough current to.

Last night they took a while to charge but did charge slower so at least I think my insulation may have kept them warm enough to charge up.

Firmware was recently updated as I posted above.
Problem is I think installer isn't quite up to full knowledge of the technicalities of the system.

I'm going to go back to them again, I've got a clip from the specs, note I mentioned Chinglish, "Working under extremely cold. Working in full load under extreme cold weather -30C/-22F" Im not sure how you can put that on the manufacturer specs and say slight sub zero C is enough to stop them working correctly.
 
NoNameNoNumber said:
DNO approval, is for a PV array over 6.2kW. Not inverter capacity related apparently.

We've just had another guy round.
7.2kW panels
3.6kW Sunsynk inverter
5.12kW/hrs Sunsynk battery

£14.6k
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I've not heard that one before - it should be the inverter size and it's potential/ability to dump to the Grid as far as I'm aware?
 
Mercenary Keyboard Warrior said:
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I ended up bypassing our installer to get my solaEdge login, took a bit of digging to get into their chat but might be worth trying the same with solax?

I've had a look at my grid draw when overnight charging on a day theres not much background load (although we always have some) and its looking like i'm drawing around 11.84kw over that period, taking me from 10-100% SOC, batteries are inside so sat at around 15-20c.

If I take of the preceding 2.5hrs of load as the background that comes down to 10.88 so i'd say thats in the right ballpark.

Have you got anything on your Solax Alarm history?
 
Siliconslave said:
I ended up bypassing our installer to get my solaEdge login, took a bit of digging to get into their chat but might be worth trying the same with solax?

I've had a look at my grid draw when overnight charging on a day theres not much background load (although we always have some) and its looking like i'm drawing around 11.84kw over that period, taking me from 10-100% SOC, batteries are inside so sat at around 15-20c.

If I take of the preceding 2.5hrs of load as the background that comes down to 10.88 so i'd say thats in the right ballpark.

Have you got anything on your Solax Alarm history?
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Oh you have solaedge I dont :(
Yeah your around the right draw, and my batteries were saying 15 or so as well, just checked and at 11 at the moment

I do have an alarm error, but again, they won't engage in conversation about it. "Warning Details：Bat Voltage Fault, Report Time：2022-11-28 19:25:12"
It says fixed but who knows what that means.
 
I've got a few on the SolaX inverter, grid and battery voltage errors and a BMS lost error but from a bit of digging on some Australian self install forums it sounds like this is normal as long as it keeps working :D
 
Welshman said:
Yup his suppliers telling porkies……its any inverter over 3.7kwh, nothing to do with the panels
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Odd lie to tell though when they specced 7.2kW of panels, thus by their rules requiring a DNO.
So the price included the DNO, but still only specced a 3.6kW inverter...

Edit:
Although Google confirms you are correct.
The DNO is required for any system that can supply >16A to the grid on a single phase.
3.6kW /230v = 15.6A

Befs the question, why when I asked for a larger inverter, after establishing a DNO would be included. Was I told there's no reason to...
 
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casper_uk said:
I can tell my system to charge through the app, it will say it is, but never does.
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it might need an update - when ours was installed it wasn't great but has improved. Be aware there is a lag on the app, but think that applies to the web as well. Rumour has it that you can connect a pc directly to the inverter and get realtime results but not had a play with that yet.
 
NoNameNoNumber said:
Odd lie to tell though when they specced 7.2kW of panels, thus by their rules requiring a DNO.
So the price included the DNO, but still only specced a 3.6kW inverter...

Edit:
Although Google confirms you are correct.
The DNO is required for any system that can supply >16A to the grid on a single phase.
3.6kW /230v = 15.6A

Befs the question, why when I asked for a larger inverter, after establishing a DNO would be included. Was I told there's no reason to...
Click to expand...
I know im correct because my own system is built around a 3.6kw inverter, with no dno requirement, only had to inform when system was fitted……
 
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By my understanding:

DNO application for G98 is done for any export capacity below 3.6KW, it's also auto approved and is done post install as a notification.

If inverter can export above 3.6KW you need a G99 which must await approval and can have costs from the DNO.

I think there is a version that can be used to auto approve G98 with a G99 appearing later.

Larger inverter can be limited by installer to G98 spec as well I think.
 
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