PV back on the table?

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Tinbum
Posts: 1127
Joined: Mon May 31, 2021 9:55 pm

Re: PV back on the table?

#11

Post by Tinbum »

I've put my Growatts up for sale but, to be honest, I'd be quite happy to keep them as they have been really good. I'm slowly working on the RS485 communication to see if I can figure it out. The batteries don't power up unless they have communication with their current BMS. I can see the communication but I'm still trying to learn about how Modbus RS485 RTU protocol works.
85no 58mm solar thermal tubes, 28.5Kw PV, 3x Sunny Island 5048, 2795 Ah (135kWh) (c20) Rolls batteries 48v, 8kWh Growatt storage, 22 x US3000C Pylontech, Sofar ME3000's, Brosley wood burner and 250lt DHW
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Paul_F
Posts: 209
Joined: Tue Jun 01, 2021 6:31 pm

Re: PV back on the table?

#12

Post by Paul_F »

Fag-packet maths here - this is taken from our planned new-build which we've just asked the architects to submit for planning permission:
  • 15.5kW of panels on a SW/NE alignment - cost of panels + GSE trays + inverter is ~£10k at Midsummer Wholesale.
  • Covers ~73m2 of roof area - cost saving from not needing tiles or slates @ £30/m2 is ~£2k. This should roughly balance out the additional wiring and installation costs given that scaffolding will already be there and first fix wiring is happening anyway.
  • Output is 12.7 MWh/year. Value is between 5-25p/kWh (depending on assumptions about self-consumption, electric cars, home battery, wholesale prices, etc.) - £635 to £3175 value.
  • Working assumption for our situation is ~15p/kWh on average - this gives payback of about 7 years.
Batteries don't work for us given the normal price of hybrid systems + batteries in the UK. There are hybrid inverters out there which are cost effective for us (e.g. this Sungrow one) - unfortunately 3-phase inverters aren't really very common over here so we'd probably need to import it ourselves. If so I might be very tempted to take a gamble on buying some LiFePO4 battery sets (not just the cells) on Alibaba although almost certainly not as part of the build.
Tinbum
Posts: 1127
Joined: Mon May 31, 2021 9:55 pm

Re: PV back on the table?

#13

Post by Tinbum »

Remember for new build in the UK you get the VAT back on most things- not white goods (which they are very keen on).
85no 58mm solar thermal tubes, 28.5Kw PV, 3x Sunny Island 5048, 2795 Ah (135kWh) (c20) Rolls batteries 48v, 8kWh Growatt storage, 22 x US3000C Pylontech, Sofar ME3000's, Brosley wood burner and 250lt DHW
AE-NMidlands
Posts: 2061
Joined: Wed Jun 02, 2021 6:10 pm

Re: PV back on the table?

#14

Post by AE-NMidlands »

For retro-fits is it right/correct that you get a battery at a lower rate of VAT, a solar alone at the full rate, but all of a solar-with-battery at the reduced rate? (except the labour, of course)
A
2.0 kW/4.62 MWh pa in Ripples, 4.5 kWp W-facing pv, 9.5 kWh batt
30 solar thermal tubes, 2MWh pa in Stockport, plus Congleton and Kinlochbervie Hydros,
Most travel by bike, walking or bus/train. Veg, fruit - and Bees!
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Stinsy
Posts: 2885
Joined: Wed Jun 02, 2021 1:09 pm

Re: PV back on the table?

#15

Post by Stinsy »

AE-NMidlands wrote: Sat Dec 04, 2021 2:13 pm For retro-fits is it right/correct that you get a battery at a lower rate of VAT, a solar alone at the full rate, but all of a solar-with-battery at the reduced rate? (except the labour, of course)
A
Correct. Batteries are 5% if bought att he same time as solar installation. 20% all other times...
12x 340W JA Solar panels (4.08kWp)
3x 380W JA Solar panels (1.14kWp)
5x 2.4kWh Pylontech batteries (12kWh)
LuxPower inverter/charger

(Artist formally known as ******, well it should be obvious enough to those for whom such things are important.)
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Paul_F
Posts: 209
Joined: Tue Jun 01, 2021 6:31 pm

Re: PV back on the table?

#16

Post by Paul_F »

Tinbum wrote: Sat Dec 04, 2021 1:03 pmRemember for new build in the UK you get the VAT back on most things- not white goods (which they are very keen on).
I've not forgotten - those prices are ex-VAT. Worth clarifying for others though...
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