Will solar panels save us money?

sazzlelondon

Hi i’m reposting in this thread after positing in the energy area, as a few people said this is the place to get more advice!

My 80 year old parents own a semi detached 3bed house and use c. 4500 kwh electricity / yr. They have been quoted for solar PV panels that should give them more energy than they use on average per year. With rising gas prices we are even considering installing an electric water cylinder to be powered by the panels. My father is thinking also to install a battery for storage. My father’s intention is to simply reduce outgoings in the long term so that if he gets ill or passes, there is less to worry about to upkeep the home. But I can’t help thinking, if save money was that easy why haven’t more people gone solar? I worry about whether the projections can be trusted. Do solar panels really save you money in the long term? Any thoughts on whether solar really does create long term savings?

The quote received:

Company: Green Eco Solar Solutions (GESS)

They have advised its probably best to install the panels get some usage and think about a battery later. 

A few quotes for Solar PV based on 310w panels (they advised this would be better for us that than the larger 390 panels and total system kWp is similar.

1. Standard Inverter System - box/string inverter 
5,667kWh/ yr installation £7300 inc VAT

2. SolarEdge Inverter & Optimiser System
6233 kWh/ yr installation £7900 inc VAT

3. Enphase Micro Inverter System
6800 KWh/ yr installation £7900 inc VAT

4. Solax Hybrid PV System with 4.5kW battery storage
6200 kWh/ yr installation £11500 inc VAT

Above prices include tech survey, IWA.biz insurance protection, NAPIT building & electrical certification, Roof Team, PV Generation Meter. Panels cabling and sundries in accordance with MCS guidelines, MCS certification, scaffolding, DNO notification

prowla

Who owns the roof once the panels have been installed?

QrizB

I don't think you've said exactly what the nominal output of the system will be, how many watts peak? Alternatively, how many 310 watt panels have they offered, I'm guessing somewhere between 20 and 24?

If so the standard system price is in the right sort of ballpark. Whether the upgrades are worth it really depends on your location; SolarEdge or Enphase are a benefit for part-shaded roofs but are extra toys if not - not that there's anything wrong with toys!

Adding £4k for a 4.5kWh battery (the "Solax hybrid" is akin to the basic string system, just with an added battery) seems a bit steep when the difference in cost is closer to £2.5k (compare eg. this to this plus two of these).

sazzlelondon

prowla said:

Who owns the roof once the panels have been installed?

Well the house is owned by my parents and there is no mention in the quote of some sort of lease arrangement, i’ll double check but i assume my parents continue to own the roof

sazzlelondon

They have quoted 13x310w panels for 4.03kWp vs 10x400w panel for 4kwp - if thats what you mean? Sorry new the lingo.

Solarchaser

3 looks best value for money, and micro inverters will do well for you.

However at 4500kwh, your house is fairly low usage.
I think you would struggle to use 2000kwh with your 6.8kw array.

If I assume you are in South England then you will probably generate around 6500-7000kwh per year.
If you use 2000 then that leaves 4500 at 5p export seg which equates to around £225 a year.

If we assume you are paying 15p/kwh then the 2000 will save you £300 / year.
So combined you are looking at roughly (all roughly) £525 a year for a £7900 cost is about a 15 year payback.

For such a low user I don't think batteries would be advisable

sazzlelondon

Solarchaser said:

3 looks best value for money, and micro inverters will do well for you.

However at 4500kwh, your house is fairly low usage.
I think you would struggle to use 2000kwh with your 6.8kw array.

If I assume you are in South England then you will probably generate around 6500-7000kwh per year.
If you use 2000 then that leaves 4500 at 5p export seg which equates to around £225 a year.

If we assume you are paying 15p/kwh then the 2000 will save you £300 / year.
So combined you are looking at roughly (all roughly) £525 a year for a £7900 cost is about a 15 year payback.

For such a low user I don't think batteries would be advisable

Thanks thats so helpful. We are thinking of moving from gas to electricity too, ie water tank heated by electricity. Do you think thats a good idea?

Solarchaser

From a green and ethical point of view definitely,  however from a cost point of view probably not.

The solar will ensure free hot water all summer, but in winter is when you need it most, and so you will end up paying more to heat the house than you would with gas.

I'm not saying its a bad idea, I plan to do exactly that, I'm just saying be aware of the costs involved

QrizB

sazzlelondon said:

They have quoted 13x310w panels for 4.03kWp vs 10x400w panel for 4kwp - if thats what you mean? Sorry new the lingo.

Thanks, yes.

I don't know how they can calculate that you'll generate 5667-6800 kWh/yr from a 4.03kWp array - typically the best you'll see is one kWh per year per watt of panel, less if you're in the north of the UK. Your parents don't happen to live in Spain or North Africa, by any chance?

If those quotes are for a 4kWp array they are a *lot* less reasonably priced.

sazzlelondon

QrizB said:

sazzlelondon said:

They have quoted 13x310w panels for 4.03kWp vs 10x400w panel for 4kwp - if thats what you mean? Sorry new the lingo.

Thanks, yes.

I don't know how they can calculate that you'll generate 5667-6800 kWh/yr from a 4.03kWp array - typically the best you'll see is one kWh per year per watt of panel, less if you're in the north of the UK. Your parents don't happen to live in Spain or North Africa, by any chance?

If those quotes are for a 4kWp array they are a *lot* less reasonably priced.

OK, the way it has been explained to me - is as we are West facing based in Surrey the eradiance (not sure how to spell that) is c914 per 1kw of solar. So he is estimating to generate 5,000kw electricity we need 16 x 310w panels generate 4.96kw system of solar. So 4.96kw x 914 = 4533.44 kw a year per system. And if we use micro then there is 20% efficiency creating 5000+ kw. 

Thats how i’ve understood it. 

JKenH

Given the age of your parents I wouldn’t consider solar panels to be worthwhile. They would need to live to about 95 to break even and while hopefully they will, statistically that is unlikely. The panels are unlikely to add value to the house and may complicate the sale procedure. 

For many people solar panels are fit and forget but not in all cases. I currently have reduced output from my 3 year old panels and despite calling in a specialist I still don’t know the precise cause and therefore how much it will cost to fix. Some people say panels need regular cleaning to maintain peak output and as that is something your parents are unlikely to be able to undertake that could be additional expense and hassle. 

Then there is the “opportunity cost” to consider. Interest rates are poor at the moment but investing the money in a stocks and shares ISA would provide a tax free return and (hopefully) preserve capital. Or you could consider buying a share in a community wind or solar scheme (not my choice but it appeals to some) - see this thread. 

https://forums.moneysavingexpert.com/discussion/6127314/green-ethical-investment-news-and-suggestions

£5/6000 is a sum your parents might find useful to have for any emergency. The NHS is in a state of disarray and old folks aren’t their priority. While that sum might not buy you much private medical treatment it would let them get to see a specialist earlier than otherwise.