2 solar/battery quotes with quite different approaches - would welcome thoughts...

chris_cooper

Background - Slate roofed chalet bungalow on South coast of Sussex, roof is a couple of degrees off due south at 45 degree angle. Can accommodate 2 rows of panels 6 on top, 7 underneath of which the middle 3 may get some shading during winter months

Currently using 7,050kw pa but do have EV on order doing approx 12,000 miles/yr so this will go up. Work from home 50% of the time so will be around to make use of energy generated.

Whilst decent ROI is obviously ideal I'm as much interested in moving towards sustainability so that isn't the be all and end all.

1st quote suggested in roof system - his argument being that the cost of GSE system will be offset by the reduced labour - hmmm, not so sure on that but.... I dunno?

Main points - 13x Eurener Zebra 375W, GivEnergy 3.6kW Hybrid inverter, 2x GivEnergy 5.2kWh Battery (this was my suggestion due to the unknown delivery status of larger battery)  £7,971 for (all) equipment £2,500 for labour and £750 for other odds and sods for total £11,221. Suggested ROI 9 years

2nd quote on roof approach, 13 Perlight 400Wp panels, SolarEdge single phase hd-wave invertor (model not specified), Solar edge optimisers, 10kwh SolarEdge Energy bank battery. All equipment £11,518 labour £1,560 for total of £13,078 Suggested ROI 8 years

Quite a big difference in price, which is affordable, but is 2 an £1,800 better system? I have asked the 1st chap to quote for 400w panels but he's not come back to me as yet.

I was leaning towards givenergy originally just because of good reviews/youtube channels suggestions etc but not 100% sold on it.

Thanks in advance for your time, I know there are a lot of these requests on here.

EcoScruples

£1800 cheaper for a kit that does the same job I'd go with the 1st option.
Sounds a good price for in the roof which will look quite nice on a slate roof.

1961Nick

If you go for the in roof system, you could sell the slate for a couple of hundred pounds.

arty688

The 2nd system will have a better discharge rate (might mean you use more of your generated electric) and optimisers (depending on the shading and as its in winter you are more likely to use the electric so is more valuable) .

what’s the warranty like for each system?

Also the second system might be considered better quality kit 

In roof is less efficient as it gets hotter but looks nicer.

chris_cooper

EcoScruples said:

£1800 cheaper for a kit that does the same job I'd go with the 1st option.
Sounds a good price for in the roof which will look quite nice on a slate roof.

That's what I thought initially, but am I comparing a Golf to a Bentley?

arty688 said:

The 2nd system will have a better discharge rate (might mean you use more of your generated electric) and optimisers (depending on the shading and as its in winter you are more likely to use the electric so is more valuable) .

what’s the warranty like for each system?

Also the second system might be considered better quality kit 

In roof is less efficient as it gets hotter but looks nicer.

Batteries both carry 10 year warranties and both sets of panels offer 15 year product and 25 year output warranty so I'm inclined to go for the cheaper option, just wasn't sure about the quality of the kit. If SolarEdge was significantly better then I'd consider stumping up the extra but if the difference is minimal then seems daft to...

arty688

the warranty on the inverter is probably more important.
the second system will generate more as its bigger, on roof and has optimisers. If that’s £1800 worth no idea you will also use more of it as it has a higher discharge rate. Another advantage will be if you have a faulty panel or poor performing one it will be less affected.

NoobSolar

You need at least a 4 kW HD Wave inverter, maybe more. If you can slightly up the capacity by one panel you might want to seek a 5kw inverter and g99 certification for export of higher than the basic 3.68kw they allow by default.

I hate the slate roof. I assume your installer is completely sure about how the hell they propose to get the supports, panels and rails on there because you can't walk about on slate.

The thing is, the solaredge system with optimisers you have there is vastly superior in two ways. First the optimisers will counteract any shading or underperformance of a single panel, and they will show you in the app the performance of each individual panel. Should a neighbour have a roof extension it will hardly change your generation at all. Secondly that is a very good battery with a high capacity there.

You ought to be considering an 'iboost plus' if you have a hot water cylinder also BTW.

Stupid thing to ask perhaps, but I assume you are replacing the roof and have quoted for that in the case of quote 1? The installer will not be intending to do that included in the price, I assume.

See whether installers will agree to be paid, or part paid, upon receipt of the DNO g99 approval. Quite a lot of them just don't do it at all until you make their lives a misery. Even good ones.

1961Nick

If you’re replacing the roof you could consider an in-roof system?

chris_cooper

NoobSolar said:

You need at least a 4 kW HD Wave inverter, maybe more. If you can slightly up the capacity by one panel you might want to seek a 5kw inverter and g99 certification for export of higher than the basic 3.68kw they allow by default.

I hate the slate roof. I assume your installer is completely sure about how the hell they propose to get the supports, panels and rails on there because you can't walk about on slate.

The thing is, the solaredge system with optimisers you have there is vastly superior in two ways. First the optimisers will counteract any shading or underperformance of a single panel, and they will show you in the app the performance of each individual panel. Should a neighbour have a roof extension it will hardly change your generation at all. Secondly that is a very good battery with a high capacity there.

You ought to be considering an 'iboost plus' if you have a hot water cylinder also BTW.

Stupid thing to ask perhaps, but I assume you are replacing the roof and have quoted for that in the case of quote 1? The installer will not be intending to do that included in the price, I assume.

See whether installers will agree to be paid, or part paid, upon receipt of the DNO g99 approval. Quite a lot of them just don't do it at all until you make their lives a misery. Even good ones.

Thanks noob, good info about the solaredge system. I was leaning that way after doing a bit more research and I think this confirms it.

We might just be able to squeeze an extra panel on, but it'll be really tight - can't do it with the first quote due to the modular nature of the GSE system he suggested. Roof isn't being replaced, he said it would be easier and quicker to just rip out the slates and put the in roof system in its place, the saving on labour would ~equal the cost of the GSE system (Although he's charging £1,000 more in labour!!) 

TBH I have more confidence in the 2nd chap, at least he took the time to look at the consumer unit and also detailed in the quote how he'd be applying for the DNO. He's listed a Renusol roof mounted system using Genius flashings in the quote which seem to be ok from a quick google.