Solar Panels UK - is it worth it?

[JIBYC]

What you mean?

Idea for me is: use 8 kwp solar (4 kwp east + 4 kwp west) for household usage and to top up batteries (9kwh) for the time when sun is not there until 23:30 when IO kicks in.
Once IO off peak ends - use battery which is top upped during IO off peak time until sun is back on (5:30 to 10 am..?)

Rince and repeast

In winter cloudy days I might struggle to live with solar during peak and will dip in battery during day and might even import a bit

All other excessive solar will spill into car (pod point charger .. so dunno how this will go) or will be exported

I might increase battery capacity in the future as it woll be significantly easier to do as no scaffolding or expensive solar installation is needed, just plug in additional batteries

I rarely need more than 4 peak KW (kettle + washing machine or oven). Kettle + oven would be 4 kw
Pylon battery will output 6 kw

Battery output will be capped at whatever the inverter can push into AC.

 

[Pete UK]

Again, I'd run it through solar.nrel.gov to check the peaks n troughs, get a feel for the generation curves. I've always said more is more, but do check what those north facing are really contributing. Could be they are making big differences on cloudy days - my NE ones help with this and get charging started early in the morning, or it could be they don't contribute enough if they need expensive scaffold to fit. Not saying one way or another, just advising to run the numbers to check! Cheaper to do it in excel rather than reality, and I've not mucked around with actual north facing arrays enough to have an opinion.

I ran it by numbers of days I could be completely independent, number I could manage with overnight plus solar, and number that I would be stuck using the grid. My 8 NE shifted a lot more days into category 2, and even squeezing 1 extra SW panel on fitting day moved about 10 days.

Check peak production and that your batteries can absorb it fast enough. Otherwise I'd say go for it if you have the capital spare, will save in the long run!

I’ve had 3 or 4 quotes with similar generation numbers and curves, so I suspect they are all coming from a reasonably accurate, maybe even slightly pessimistic forecast (hopefully!). But I’ll double check that. Thanks for the link.

Dec/ Jan generation is forecast at 4-6 kW per day. Summer 4 months is at 28-34kW per day.
Batteries can charge at 3.6kW each pair of two on an inverter (7.2kW total). So each inverter charges 19kW/ 3.6 is 5 1/4 hours to charge fully from grid. Or if using 5% to 95% that’s 17.1/3.6 or 4 3/4 hours.

I think 2 batteries on each inverter is about the best that can be achieved with the grid charging rates of the GivEnergy 9.5’s. And the inverters input. The battery discharge rate is 5kW each inverter (so 10kW, which would seem enough for the house most of the time).

I’m viewing the north facing ones as panels that are twice the price of the equivalent panels on the south side. So to get the equivalent generation of 4 extra on the south side I need 8 on the north side, as they only produce half the amount. I know that’s simplistic and generation times will be different etc etc but the incremental cost of 8 panels on the north while they are here isn’t that much more than if I was putting 4 extra on the south. (Cost of 4 panels, plus a bit more scaffolding. Maybe 10-15% more?). I’m stuck with my roof so I don’t have the option for more on the South side. Other that not putting them on the North at all and maybe missing 1,700kW of generation per year.

My roof is L shaped. Like the fat “L” on a learner drivers plate, so there is a bit extra scaffolding for the north side but not much extra. The horizontal part of the L is the bit that faces South; ie down is south. The long bit of the L is the part that faces East (apologies I said West facing in my earlier post by mistake, I meant East, but numbers work the same).

I’m using 19,000kW pa (4,500kW of that is the car. Which will mostly come from off peak on IO).

I’m pretty sure the proposed set up will be like this;

East facing;
1x 5kW GivEnergy inverter - peak panels: 5880kW
String 1 - 6 panels (2,520kW)
String 2 - 8 panels (3,360kW)

South and North facing;
1x 5kW GivEnergy inverter - peak panels: 5460kW
String 1 (S) - 5 panels (2,100kW)
String 2 (N) - 8 panels (3,360kW)

27x 420w panels
2x GivEnergy 5kW hybrid inverters
4x 9.5kW GivEnergy batteries.
GivEnergy hot water diverter (when released!)

So the whole system (in theory anyway) kind of seems the optimum I can get. To cover winter off peak and summer generation, without overspending on Solar edge batteries and inverters. Which cost about £10k more installed. I’ve read hundreds of forum pages and pretty much guided/told the installers what I think I need to reduce my bill the most.

Only think I’m hesitating on is; what if energy suppliers prices drop? Wholesale prices have come down a lot, so in theory, we should start to see that soon. I dunno though. Will they?

Does my proposed system make sense? Am I missing anything crucial here or does it seem bang on, best case for my situation?

 

[Avendit]

I’ve had 3 or 4 quotes with similar generation numbers and curves, so I suspect they are all coming from a reasonably accurate, maybe even slightly pessimistic forecast (hopefully!). But I’ll double check that. Thanks for the link.

Dec/ Jan generation is forecast at 4-6 kW per day. Summer 4 months is at 28-34kW per day.
Batteries can charge at 3.6kW each pair of two on an inverter (7.2kW total). So each inverter charges 19kW/ 3.6 is 5 1/4 hours to charge fully from grid. Or if using 5% to 95% that’s 17.1/3.6 or 4 3/4 hours.

I think 2 batteries on each inverter is about the best that can be achieved with the grid charging rates of the GivEnergy 9.5’s. And the inverters input. The battery discharge rate is 5kW each inverter (so 10kW, which would seem enough for the house most of the time).

I’m viewing the north facing ones as panels that are twice the price of the equivalent panels on the south side. So to get the equivalent generation of 4 extra on the south side I need 8 on the north side, as they only produce half the amount. I know that’s simplistic and generation times will be different etc etc but the incremental cost of 8 panels on the north while they are here isn’t that much more than if I was putting 4 extra on the south. (Cost of 4 panels, plus a bit more scaffolding. Maybe 10-15% more?). I’m stuck with my roof so I don’t have the option for more on the South side. Other that not putting them on the North at all and maybe missing 1,700kW of generation per year.

My roof is L shaped. Like the fat “L” on a learner drivers plate, so there is a bit extra scaffolding for the north side but not much extra. The horizontal part of the L is the bit that faces South; ie down is south. The long bit of the L is the part that faces East (apologies I said West facing in my earlier post by mistake, I meant East, but numbers work the same).

I’m using 19,000kW pa (4,500kW of that is the car. Which will mostly come from off peak on IO).

I’m pretty sure the proposed set up will be like this;

East facing;
1x 5kW GivEnergy inverter - peak panels: 5880kW
String 1 - 6 panels (2,520kW)
String 2 - 8 panels (3,360kW)

South and North facing;
1x 5kW GivEnergy inverter - peak panels: 5460kW
String 1 (S) - 5 panels (2,100kW)
String 2 (N) - 8 panels (3,360kW)

27x 420w panels
2x GivEnergy 5kW hybrid inverters
4x 9.5kW GivEnergy batteries.
GivEnergy hot water diverter (when released!)

So the whole system (in theory anyway) kind of seems the optimum I can get. To cover winter off peak and summer generation, without overspending on Solar edge batteries and inverters. Which cost about £10k more installed. I’ve read hundreds of forum pages and pretty much guided/told the installers what I think I need to reduce my bill the most.

Only think I’m hesitating on is; what if energy suppliers prices drop? Wholesale prices have come down a lot, so in theory, we should start to see that soon. I dunno though. Will they?

Does my proposed system make sense? Am I missing anything crucial here or does it seem bang on, best case for my situation?

All sounds really good TBH. Using the nrel site was more to get a feel for peaks and troughs on an hourly basis than because I thought the quotes would be off - I think they all use the same datasets so should be similar.

Only challenge to your system I would give is could you down size the South and North facing inverter at all? ie will you actually get the 2k and 3.3 kw at the same time ever, or will for practical purposes it max out at about 4? If you want to keep that 10kw discharge rate on the batteries then that is more important, but the panels might be a little more efficient with a smaller inverter. Check the spreadsheets for the peak actual peak of those 2 strings and possibly resize. But you are into very fine tuning here!

 

[Pete UK]

I only tried a North projection recently - I was really surprised at how good it was. More than 50% in mid-Winter (and of course that's 50% of pretty-much-nothing), and 80+% of Summer ... definitely not to be sneezed at!

Also, I suspect (no evidence) that North is better (than South) for Sun Rise / Set in Mid Summer (as the Sun is well North of true East / West) - so if that's right it will lengthen the Solar Day (and shorten the duration of Solar-night-without-PV/from-Battery )



I think that's pessimistic

I had a go with PVWatts for my Lat / Long using the default "System Size"

View attachment 921254

Comparison of North, East, Wets against South:

View attachment 921263

I think it is worth measuring the roof "Tilt" accurately, as that might make a significant difference (much more so on North elevation prediction than South)

View attachment 921266

Assuming that PVWatts is accurate ...

EDIT: Modified last spreadsheet to show percentage difference for Roof Slope,. compared to (top image) 20% roof

Negligible for East, South, West but significant gain for a "flatter" North roof, and significant reduction for a steeper pitch North roof.

20deg seems pretty shallow. Most roofs are probably 30 plus.

That’s why I’m going to plan with 50% generation compared to South. Probably nearer 58% but I think that’s about right. Conservative is good. Better to get a nice surprise.

 

[Pete UK]

All sounds really good TBH. Using the nrel site was more to get a feel for peaks and troughs on an hourly basis than because I thought the quotes would be off - I think they all use the same datasets so should be similar.

Only challenge to your system I would give is could you down size the South and North facing inverter at all? ie will you actually get the 2k and 3.3 kw at the same time ever, or will for practical purposes it max out at about 4? If you want to keep that 10kw discharge rate on the batteries then that is more important, but the panels might be a little more efficient with a smaller inverter. Check the spreadsheets for the peak actual peak of those 2 strings and possibly resize. But you are into very fine tuning here!

Yeah, that’s a tough call. Need the 5kW inverters to be able to use the fully welly from the batteries in the winter. I’ll check the 3.6’s to see what their output is for charging from grid/solar and discharging rates etc. they all seem to have different rates for everything

Minefield this ain’t it?

Edit - Seems a smaller inverter might work on the N/S - good call. The 3.6 hybrid will go to 4,500 on the panels.

looking at the data sheets, I think GivEnergy need to update it though . They are saying 2,600 battery discharge for both the 3.6 and 5.0 inverters but that’s not right is it? Thought the hybrid 5.0 could do 3.6kW from the 9.5kW battery?

My head hurts now.

 

[WannabeOwner]

20deg seems pretty shallow. Most roofs are probably 30 plus.

My observation from the PVWatts data is that 30deg roof pitch makes negligible difference to South (1%), tiny for East/West (6%) but a fair bit to North (16%)

So for North I think it is worth actually measuring the slope

I’m viewing the north facing ones as panels that are twice the price of the equivalent panels on the south side
...
I’m going to plan with 50% generation compared to South. Probably nearer 58% but I think that’s about right.

I still think that's pessimistic. At 30deg slope the summer is only 20-30% less than South (plus generating-day-length gain / night-length reduction, which translates to more "useful" PV)

Better to get a nice surprise.

Well ... I like data My view would be that accurate figures might influence your comfort with the expenditure.

Only think I’m hesitating on is; what if energy suppliers prices drop?

He who hesitates ...? I did it before Electricity price increase ... I didn't worry too much about the numbers, turned out Putin gave me a gift. But I may have a different perspective: I'm retirement age, in my forever home, so I have locked in my energy price in retirement - roughly speaking 80% of my electricity bill now comes from my PV ... so going forwards I only have to pay 20% of my bill. I see it like insurance ...

I think price will come down ... if wholesale Electricity Price becomes a free market then cheap Wind generation will drive that price down ... and we will all have Time of Use tariffs and times when consumer price will be £0 or £negative - quite likely during the day (wind blowing and sun shining causing over production - just when I, too, will have loads of PV). But equally my Battery will discharge when ToU rates (evening cooking etc.) are much higher than now.

One option: If price drops buy an energy consuming device - Hot Tub maybe? By then any 2nd-car ICE will likely be an EV too ... maybe discharge-to-gird from battery at peak times will be compensated higher too.

Need the 5kW inverters to be able to use the fully welly from the batteries in the winter

I know nothing about the hardware, but "full welly" in Winter is a lot less than in Summer - I wonder if that make a difference (to hardware sizing optimisation for Winter) ?

My absolute peak (on days when we had wall-to-wall sunshine)

26-Dec 4kW (16.8 kWh that day ... and a) precious few such days in winter and b) all "useful" generation happens between 08:00 and 14:00)
10-Jul 12kW (97.6 kWh that day - useful generation 06:00 - 18:00)

Winter PV is SO small (33% peak, 17% generation) that I'm not sure it is worth optimising for. Mid Winter overall insolation average is 10% of mid Summer at UK latitude. Shoulder months maybe ... but by March a sunny day is "more than I need" and a rainy day is still "rubbish" - the day length isn't long enough to provide the same practical benefit as the Summer months.

My head hurts now.

I just left my installer to decide everything ...

 

[yessuz]

My PV generates 15kW peak, PowerWall will only charge at max 10kW ...



So my point was will the peak kW (not day-average kWh) exceed the charge rate for your battery? (if you have e.g. Zappi that would push any excess to EV then no need to care (assuming car is parked at home / isn't already full / etc. etc.)

Just wanting to consider what the kW peaks are (from PV and into Battery) to check that you will actually be able to store, in battery, all that your PV produces. (Seems likely ... the figures aren't "big" so to speak ... but ... )

Pv set is 8 kw, but it is west/east (4.1 kwp each). So probably will peak at 7 kwp...
Each side on separate inverter, so basically 4 kwp panel side on 4 kw inverter

Battery pack is 9.2 kwh if you are asking this?

 

[WannabeOwner]

So probably will peak at 7 kwp...

So if battery can charge at that rate that's fine ... if not then do you have another use (House obviously but I suspect that's less < 1kW most of the time ... Zappi / car parked at home?)

Car would mop up 7kW so obviously that would be plenty.

Basically just wanted to raise the issue that Battery may not be able to take all the peak output from PV

 

[Pete UK]

I know nothing about the hardware, but "full welly" in Winter is a lot less than in Summer - I wonder if that make a difference (to hardware sizing optimisation for Winter) ?

I’m talking about “full welly” from what’s in the batteries in winter to cook/ heat the electric floors etc. not full welly from the solar in winter.

I like data too. What sort of numbers do you get for north facing panels for a pitch of 35, 40 and 45 degrees north? I reckon my roof is about 40 degrees. I think that’s fairly typical for UK houses and is in the region of about 50% from my investigations. I’d be interested to see what numbers you get for that angle to compare.

I’m guessing you have a 20 degree pitched north roof. Which, if that’s the case you’d get much better results in your situation. Really good results.

I originally left it all to the installers but they were coming back with some really odd designs that didn’t really work well for my needs. Like; 2 inverters with one 4.5kW battery attached to only one inverter and stuff like the usual 3.68kW max export, batteries with no app, power optimisers on some panels but not on others on the same string, etc. I’ve had to be a bit pro-active here otherwise I think I’d of got something I wasn’t happy with.

If it was a year ago and knowing what I know now, I wouldn’t be hesitating. At current electric prices, £33,000 invested today that saves me £4–5,000 a year works. But if unit prices come down a lot and it only saves me £2,000 a year then that doesn’t really work as well. Still saves - but, well, I’d be looking at about 16 and a half year ROI instead of 7 and a bit. ROI isn’t the be all and end all but in my situation I’m always going to be importing more than I can generate. So the peak import vs off peak makes a huge difference to savings. The batteries are going to save me the most. The export prices aren’t really a factor. It’s the “not buying at 40p a unit” that’s the biggest factor - for me anyway.

I saw wholesale prices have come down significantly recently. Just not filtere through to the public yet.

Maybe I’ll wait till April. See what happens with unit prices and adapt my plan as required.

 

[WannabeOwner]

What sort of numbers do you get for north facing panels for a pitch of 35, 40 and 45 degrees north?

Best you run those numbers for yourself - then you have correct latitude etc. and also you can "draw" the exact size of your roof (if you don't already have dimensions / proposed number of panels)

If you can get into loft you can measure pitch / slope of roof from inside - just need a spirit level and a tape measure (and YouTube/similar advice) ... or a tilt-angle-APP on your phone, and then just hold phone against a roof timber

I’m guessing you have a 20 degree pitched north roof

just to clarify: I don't have a North roof - I've only done a simulation, but the data source seems trusted.

I originally left it all to the installers but they were coming back with some really odd designs

I’ve had to be a bit pro-active here otherwise I think I’d of got something I wasn’t happy with

Possibly those installers are not your best choice? Although folk here bound to, collectively, spot any snags/opportunities with planned installs - then getting a lacklustre (if that isn't unfair) installer to implement might be a rock-uphill?

At current electric prices, £33,000 invested today that saves me £4–5,000 a year works. But if unit prices come down a lot and it only saves me £2,000 a year then that doesn’t really work as well.

That's where I'm at (Spend / Income-wise). But ... I would be happy with £2,000 - not in terms of payback, but in terms of "I invested £33,000 and got £2,000 p.a. return - tax free and inflation linked"

For folk borrowing money to do PV then the payback is relevant. For anyone able to cash in savings then I think the "alternative income" maths is good - takes a stonking investment to return 6% tax free index linked ... well, you could buy some Cannabis lights - high value crop, good return on investment, and I guess that is Tax Free and Index Linked too

 

[Pete UK]

... well, you could buy some Cannabis lights - high value crop, good return on investment, and I guess that is Tax Free and Index Linked too

Ah-ha. Now we know what you’re planning to do with all you’re excess generation

Yes - I suppose looking at savings/return as a percentage of the investment made is also a good way to look at it, instead of ROI pay pack time in years. Almost all other investments we do that !

 

[KennethS]

That's where I'm at (Spend / Income-wise). But ... I would be happy with £2,000 - not in terms of payback, but in terms of "I invested £33,000 and got £2,000 p.a. return - tax free and inflation linked"

This is an extremely good point that I think some people overlook. The return is effectively tax free and the savings will increase in proportion to any increase in energy costs in the future. Whilst we may have recently experienced an unusually steep electricity price increase, I am willing to bet that prices will only be trending further upward. Hopefully at a less steep rate but upwards nonetheless.

For this reason we are looking to add a second Powerwall2 to our system.

 

[Pete UK]

Here is a useful link. I tried to post the graphic but no luck.

Tilt and Orientation and Solar Energy

How solar energy varies with tilt angle and the direction.

www.viridiansolar.co.uk

 

[WannabeOwner]

Here is a useful link

Useful indeed, thanks

Looks like to get down to 50% from a North elevation needs the roof pitch to be 40deg - and for a roof just a little North of NE / NW that improves to 50deg. I have no idea what sort of pitch UK house rooves are, mine are very shallow.

I'll have a go at linking to the image

 

[Pete UK]

The only thing is with looking at the investment as a “savings” return, is that you can’t withdraw the initial capital outlay. It’s stuck on the roof!

So after 1 year at 6% ‘return’. If it was in the bank you’d have 106% of the total money. With it in a Solar system, after one year you’ve only got 6% of your entire money ‘invested’ back. So you’re basically 94% down. I guess that’s why everyone is ROI obsessed. Until you get to payback time you’re at a loss to the tune of the whole system cost minus your savings made up to that time.

Unit prices will always only go up, yes. But will they come back down 70% first?

End of the day it’s all a bit of a gamble but likely well worth it. Need a on the price prediction side of things. It’s almost a waste of time thinking about it.

If you look at posts from people who installed 5-10 years ago they have probably all broken even already.

 

[KennethS]

The only thing is with looking at the investment as a “savings” return, is that you can’t withdraw the initial capital outlay. It’s stuck on the roof!

So after 1 year at 6% ‘return’. If it was in the bank you’d have 106% of the total money. With it in a Solar system, after one year you’ve only got 6% of your entire money ‘invested’ back. So you’re basically 94% down. I guess that’s why everyone is ROI obsessed. Until you get to payback time you’re at a loss to the tune of the whole system cost minus your savings made up to that time.

Unit prices will always only go up, yes. But will they come back down 70% first?

End of the day it’s all a bit of a gamble but likely well worth it. Need a on the price prediction side of things. It’s almost a waste of time thinking about it.

If you look at posts from people who installed 5-10 years ago they have probably all broken even already.

All good and valid points.

As to the wisdom of locking up a significant pile of cash it is, as you say, a crystal ball exercise. My neighbours thought we were a bit mad in 2011 when we installed the solar PV on our roof, and again in 2019 when we had the Powerwall installed. They both seem to be a frequent source of questions and conversation now and a bit of wonderment when told how they have performed financially. We have never regretted the investment in either. Hopefully we will feel the same in several years if we add a second Powerwall.

 

[94jdh]

I’ve had 3 or 4 quotes with similar generation numbers and curves, so I suspect they are all coming from a reasonably accurate, maybe even slightly pessimistic forecast (hopefully!). But I’ll double check that. Thanks for the link.

Dec/ Jan generation is forecast at 4-6 kW per day. Summer 4 months is at 28-34kW per day.
Batteries can charge at 3.6kW each pair of two on an inverter (7.2kW total). So each inverter charges 19kW/ 3.6 is 5 1/4 hours to charge fully from grid. Or if using 5% to 95% that’s 17.1/3.6 or 4 3/4 hours.

I think 2 batteries on each inverter is about the best that can be achieved with the grid charging rates of the GivEnergy 9.5’s. And the inverters input. The battery discharge rate is 5kW each inverter (so 10kW, which would seem enough for the house most of the time).

I’m viewing the north facing ones as panels that are twice the price of the equivalent panels on the south side. So to get the equivalent generation of 4 extra on the south side I need 8 on the north side, as they only produce half the amount. I know that’s simplistic and generation times will be different etc etc but the incremental cost of 8 panels on the north while they are here isn’t that much more than if I was putting 4 extra on the south. (Cost of 4 panels, plus a bit more scaffolding. Maybe 10-15% more?). I’m stuck with my roof so I don’t have the option for more on the South side. Other that not putting them on the North at all and maybe missing 1,700kW of generation per year.

My roof is L shaped. Like the fat “L” on a learner drivers plate, so there is a bit extra scaffolding for the north side but not much extra. The horizontal part of the L is the bit that faces South; ie down is south. The long bit of the L is the part that faces East (apologies I said West facing in my earlier post by mistake, I meant East, but numbers work the same).

I’m using 19,000kW pa (4,500kW of that is the car. Which will mostly come from off peak on IO).

I’m pretty sure the proposed set up will be like this;

East facing;
1x 5kW GivEnergy inverter - peak panels: 5880kW
String 1 - 6 panels (2,520kW)
String 2 - 8 panels (3,360kW)

South and North facing;
1x 5kW GivEnergy inverter - peak panels: 5460kW
String 1 (S) - 5 panels (2,100kW)
String 2 (N) - 8 panels (3,360kW)

27x 420w panels
2x GivEnergy 5kW hybrid inverters
4x 9.5kW GivEnergy batteries.
GivEnergy hot water diverter (when released!)

So the whole system (in theory anyway) kind of seems the optimum I can get. To cover winter off peak and summer generation, without overspending on Solar edge batteries and inverters. Which cost about £10k more installed. I’ve read hundreds of forum pages and pretty much guided/told the installers what I think I need to reduce my bill the most.

Only think I’m hesitating on is; what if energy suppliers prices drop? Wholesale prices have come down a lot, so in theory, we should start to see that soon. I dunno though. Will they?

Does my proposed system make sense? Am I missing anything crucial here or does it seem bang on, best case for my situation?

Just watch out for the cross charging of the gen2 inverters, a new piece of kit called EMS will control it, but when it is out is anyone's guess!
There are third party solutions if you fancy tinkering.

 

[Pete UK]

Just watch out for the cross charging of the gen2 inverters, a new piece of kit called EMS will control it, but when it is out is anyone's guess!
There are third party solutions if you fancy tinkering.

Yes. Waiting for that and the GivEnergy hot water tank diverter. What exactly are the cross charging issues? Are they applicable to the Hybrid inverters or the AC inverters or both? Is it due to a set up issue or something else?

Do you have this issue on your install?

What are the 3rd party options in the meantime?

Thanks in Advance.

 

[WannabeOwner]

If it was in the bank you’d have 106% of the total money

Well ... not exactly ... coz you have to pay tax on that 6%, and you also have your electricity bill to pay ... whereas the 6% PV is matched by a reduction in electricity bill.

But, yeah, your 100% is tied up ... maybe if you sell the house you will get some back.

 

[94jdh]

Yes. Waiting for that and the GivEnergy hot water tank diverter. What exactly are the cross charging issues? Are they applicable to the Hybrid inverters or the AC inverters or both? Is it due to a set up issue or something else?

Do you have this issue on your install?

What are the 3rd party options in the meantime?

Thanks in Advance.

The cross charging wasn't there for me with the Gen1 Inverters, I believe I had the system set up completely independent to try an eliminate any chance.

It was working very well, the East would charge its battery via the associated inverter and the same via the West. The only down side was if you had better weather in the morning or afternoon, you potentially would have reduced charging to the affected battery, but in my case the panels are on flat roof areas at 10 degrees and do continue to generate all day ( although at a slightly reduced rate in comparison to the favoured side).

Once I had the Gen1's swapped out to Gen2's at the beginning of this month I noticed two issues. First is related to cross charging, whereby if one battery is at a higher capacity of charge it will begin to discharge to supplement the lower one. This can to and fro, the main problems being there will be losses and unnecessary 'wear' on the batteries being cycled.

The second issue I found, which I don't think is a problem and more of a benefit as far as I can see, either the East or West ( or both) can now charge either battery. The only problem, in my opinion is that it must be going from DC to AC and back to AC again which will also involve some losses.

To note, this was a like for like swap out so the changes in behaviour could only be in relation to the firmware ( of which I am on the latest beta for testing) and likely related to some form of AC monitoring that the Gen1's didn't have.

Both of mine are hybrid inverters, the cross charging is seen on both AC and hybrid multiple inverter set ups and apparently the AC inverter is priority for the EMS with the hybrid to follow at some point.

The software options, which I believe work very well and I'm likely to pursue myself in the short term are via Givenergy GivTCP. Facebook have a page, and have scripts ready to run to download - you just have to add some of your own details and use a raspberry Pi or something similar to operate. Link as follows:

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