Solar quote advice please 29 September 2022 at 12:06PM in Green & ethical MoneySaving 41 replies 2.2K views

NormanSpiny

After further investigation, we have decided not to go ahead with ESE group. We also rejected a quote from Project Solar for nearly £22,000!

Another quote has been obtained from Vision 2030 in Bristol, £12,425

5.6kW PV Solar Panel System with 5.12kW Battery Storage

14 x 400 watt Trina Vertex Panels

1 x 5kW Solis Hybrid Inverter

1 x 5.12kW Fox ESS Battery
1 x Scaffolding As Necessary
1 x Lifetime support
1 x DNO Application for G99 permission

This seems much better as they also included the DNO application, which was not mentioned by other companies. Also this lot have MCS accreditation. This quote was based on estimated annual consumption of 7500kW, rather than 9000 as that was based on estimated bills and is probably a bit too high. They also seemed to be more knowledgable about panel placement as other companies have suggested mounting panels on the east-facing part of our roof which seems a bit pointless, especially as we have enough space on the south and west-facing aspects.

Any opinions?

Thanks

ABrass

That's better. Still not great but much better.

Ask them if they could fit another few panels on, if you've got split aspects then having more panels than your inverter size is a good idea as they will very rarely be generating at maximum power at the same time.

East is good for early morning power, West is good for afternoon power.

Screwdriva

Sorry to say, I agree with ABrass. Not a great price and the components are bargain basement spec. 

A similar very recent quote I've seen:

14 X Sharp 400W Panels
14 X SolarEdge Optimizers
 1  X SolarEdge Inverter

25 year warranty on everything. £7K installed. Bird netting, scaffolding and travel costs extra only if needed (~£1K).

If it were my home, I'd skip the cheap battery and maximize the # of panels I can fit on my roof. I'd also definitely include 20% of the total panel count on the East aspect to take advantage of the early morning sunlight. Your instinct to focus on the South/ West aspects is correct. 

If you do spread your generation across 3 aspects, you may not need G99 application, as you will be generating from sunrise to sunset, saving you and your installer some admin. This is far more profitable vs. generating a peaky yield via your South aspect.

NormanSpiny

Why ditch the battery? Surely, it's a good idea to store any surplus and use it in the evenings?

Me + wife both work from home so our usage is mostly during the day. We have a teenage son who is out all day and isn't really a heavy user anyway. Inspecting our bills as part of this process has revealed that we are surprisingly heavy users. Our other son is away at uni so there are only three of us in the house most of the time. It was shocking to us the amount we use as we don't leave lights on unnecessarily, have gas heating, don't have electric showers etc. The only explanation that we can think of is that my wife does baking for charity so the oven is on a lot. We do also have quite a few smart devices which are on all the time, but surely their consumption must be insignificant compared to the oven? We also have a plug in hybrid which we charge on a granny charger overnight. It has a 12kW battery (I  think) and it's not charged every day.

As we don't have a smart meter (yet) it's quite hard to detemine where all the power is going.

Screwdriva

NormanSpiny said:

Why ditch the battery? Surely, it's a good idea to store any surplus and use it in the evenings? 

If you're a daytime energy heavy (baking) household, the PV will help greatly with your consumption. I'd suggest using this calculator (inputting your actual usage, using the day ahead SEG tariff, with/ without a battery arbitrage) to generate an approximate ROI.

If you're a heavy nighttime user, then a smaller battery starts to make minor sense. 

NormanSpiny said:

As we don't have a smart meter (yet) it's quite hard to detemine where all the power is going.

Definitely switch to Octopus and apply for a Smart Meter (if your existing supplier isn't fitting one for you or providing a concrete timeline). Octopus has prioritized Solar Export customers for Smart Meter fitments.

NormanSpiny

We are currently on a fixed deal with Scottish power @ 17.8p/kWh until August 2023, after that it will revert to 34p/kWh with futher increases after the govt cap expires, no doubt. After that, we will switch to a different provider.

From that online calculator:

Scottish power until August 2023:

7500kWh @17.8p and SEG 5.5p kWh with Scottish power

Payback: 16 years

Bill: £1335->£558 (approx 58% saving)

Scottish power after August 2023:

7500kWh @34p and SEG 5.5p kWh with Scottish power

Payback: 8.9 years

Bill: £2550->£1147 (approx 55% saving)

Do these numbers look reasonable?

Screwdriva

NormanSpiny said:

We are currently on a fixed deal with Scottish power @ 17.8p/kWh until August 2023, after that it will revert to 34p/kWh with futher increases after the govt cap expires, no doubt. After that, we will switch to a different provider.

From that online calculator:

Scottish power until August 2023:

7500kWh @17.8p and SEG 5.5p kWh with Scottish power

Payback: 16 years

Bill: £1335->£558 (approx 58% saving)

Scottish power after August 2023:

7500kWh @34p and SEG 5.5p kWh with Scottish power

Payback: 8.9 years

Bill: £2550->£1147 (approx 55% saving)

Do these numbers look reasonable?

To answer the battery/ no battery question, I ignored your next 10 months with SP and presumed you will switch to Octopus in Aug '23, given the substantially higher SEG tariff that is Outgoing Agile.

Based on the above usage of 7500kWh and a 5.6 kW system where you sell excess via Outgoing Agile, I get the following two scenarios. Unless I've misunderstood something, it looks like a 10 kWh battery doubles the payback period. That's in addition to requiring £6K upfront. 

no battery:



w/ battery:

Alnat1

Possible power guzzlers are older inefficient fridges and freezers, especially American type which have been found to use up to 3kWh a day. I suggest investing £10 or so in an energy monitor (I use a Tapo P110 which doubles as a smart plug after) and checking how much your appliances are using.

Alnat1

With a solar and battery system you'll probably use very little grid electricity from Mar-Sep. It might be worth switching to Octopus around March to take advantage of the much higher SEG payments. With the size system you are looking at you will be exporting a lot over summer.

I definitely recommend a battery which would give you free overnight power most of the year. I find the Octopus Agile tariff allows me to fill my battery overnight when they have cheap time slots available and that is a big advantage in the less sunny months. They also have the Go tariffs for EV owners which give cheap hours every night, although you get paid less for export when on those.

NormanSpiny

Alnat1 said:

Possible power guzzlers are older inefficient fridges and freezers, especially American type which have been found to use up to 3kWh a day. I suggest investing £10 or so in an energy monitor (I use a Tapo P110 which doubles as a smart plug after) and checking how much your appliances are using.

I have an energy monitor socket like that, but I really need something that will monitor the whole house usage. I've been resisting a smart meter for a while, maybe it's time to give in. I know I'll need one when the solar system is installed.