Solar quote advice please 29 September 2022 at 12:06PM in Green & ethical MoneySaving 41 replies 2.1K views

DougMLancs

You can get whole house meters that’ll give you an overall picture too - something like this https://www.amazon.co.uk/dp/B00JIMQP6Y?tag=switchinglimi-21&linkCode=ogi&th=1&psc=1

NormanSpiny

I ran the numbers through the calculator with and without arbitrage. I don't really undertand this, but it seems like I would be exporting more and then buying it back again at a cheaper rate? This seems a bit pointless to me as I would rather be using what I generate myself. Have I got the wrong end of the stick? Please explain.

With arbitrage:

Without arbitrage:

Screwdriva

Theoretically, arbitrage should mean you sell energy when it is the most profitable (early mornings and late evenings) and buy when it is the cheapest, in this case via your rooftop PV. 

In either case, your return on investment is substantially delayed with a battery, as has been the case for many selling via Octopus Outgoing Agile. Those advocating a battery today either have a very different usage pattern or have based their advice on experience from a time when the SEG tariff was substantially lower than what it is today. 

The best part is that you can always add a battery onto a system designed for it at a later time. You may have to pay VAT on it, but you'll get one that will have advanced considerably from options available today. 

ABrass

That arbitrage option is clearly awful in the current market.

If you assume your battery will last 10 years or more then you end up saving more with batteries. If you assume they won't then batteries are a poor investment. 

The 'buy it later' option only makes sense if you think that the battery tech will improve by the amount you save each year. So if your battery is going to save you £200 a year then waiting needs to see a price drop of £240 a year (+%20 due to VAT). Its not impossible.

Alnat1

Having a battery at this time of year means I can cook dinner and get my evening's entertainment powered for "free" after sunset. It also powers the load overnight but now runs out before breakfast. In summer the battery often didn't drop lower than 30% before starting to refill the next morning.

Sometimes in the early hours Octopus Agile has had cheap (even negative priced) slots and I've been able to top the battery back up. It means I spend less on peak rate energy. Over the last 28 days I've imported an average of 2.18kWh/day @ 18.14p. 

Batteries are also a new toy. The glee of being able to set it to fill at 2.30am and being paid 9p/kWh to do it, cannot be measured by ROI calculator. Those who only have PV miss out on that feeling 

Screwdriva

Alnat1:

Those who only have PV miss out on that feeling   

I suppose OP and others considering a battery will need to ask themselves if they want to spend £6K or more for that “feeling”.  Or if that £ can deliver other more gratifying ways to offset carbon, such as a heat pump or down payment on an EV.

TheTwillows

I have 2 quotes which are , and tbh are wildly differant especially with regard to planning permissions, what do those more knowledgeable than I think?

I surrently consume 5000-6000 kWh per annum and the array would be split over 2 roofs facing S30 deg E and S 30deg W.

Quote 1

• 20 x 370w Black Mono Panels
• 1 x 5 kw FOX ESS Hybrid Inverter
• On Roof Fixings
• AC & DC Isolators
• Generation meter
• All Cabling
• Scaffold Included
• Bird guard
• I boost
• MCS Certification
• Commissioning and Hand Over Pack
8.2 kw FOX ESS Hybrid Energy Cube Battery Storage System
• 2 x 4.1 kw Energy Cube Batteries
                                                                                                                              £17,689 all in

Quote 2

20 Trina solar 400 panels                                                     £ 3,430.00
1 6 kW Luxpower solar hybrid inverter                                 £ 1,800.00
2 3.2 kW Greenlink batteries                                                £ 3,000.00
1 All rail, hooks and clamps                                                     £ 800.00
1 Electrical sundries                                                                    200.00
                                                                 Materials Subtotal £ 9,230.00

1 Scaffold                                                                                     800.00
1 Installation of on-roof solar panels                                      £ 1,250.00
1 Electrical installation                                                            £ 1,400.00
1 NICEIC and MCS certification                                                   100.00
1 G99 application to local DNO (indicative price)                      £ 640.00
                                                                  Services Subtotal £ 4,190.00
                                                                                                                            Total £ 13,420.00

ABrass

Quote 2 isn't bad. Quote 1 is bad.

TheTwillows

Am I best to get G99 approval prior to commiting to any work?

ABrass

TheTwillows said:

Am I best to get G99 approval prior to commiting to any work?

The process is (I believe, I'm not an expert) that a quick notification goes into the DNO to let them know roughly what you're doing. They give a quick yes/no to the system and then you install and get it all signed off fully once completed.

The worst outcome is that you'd have to limit your export to 3.68kW. But most modern inverters can do that now anyway I believe.