Solar panel quote

Aussie_Tips

https://forums.moneysavingexpert.com/discussion/comment/82079306#Comment_82079306

I'm going to disagree with this position as there are a few inaccuracies. Primarily the solar savings are based on a 6kwp array and £12k - and a 6kwp array doesn't cost £12k

Baseline - Imagine a household with an average consumption of 10kwh per day and £8k in the bank. Each year the £8k will earn say £400 in interest (based on 5% return) and their electricity will cost just over £1k (based upon 27p/kWh) - that's a net loss of £600. So after around 13 years the £8k savings would be effectively gone and there would still be an annual bill of £1k. After 20 years they'd be down - £7k and getting worse by £1k every year

Solar & battery - The market price for 5kwp of solar is around £4k, and a 10kwh battery is around £4k fully installed (I know it varies depending on complexity etc - but this is the market price). So a 5kwp array & 10kwh battery should cost around £8k

With this sized battery alone and an appropriate off-peak tariff, the system would cover a proportion of the household consumption - let's say 50%. So the peak rate part of the annual bill will be say £500, with 1800kwh (5kwh/day) being off-peak via battery. So thats 45p/day (based on off-peak tariff at 9p/kWh) or £160 per year. So the total annual electricity bill would be £660. That's from the battery alone.

We also know that 1kwp of solar will generate roughly 0.8-1Mwh per annum. Using the low end figure of 0.8Mwh, if this was all exported at 12p/kWh it would make £96. So a 5kwp system would return £480 per year if everything was exported. This would give you a net annual electricity bill of around £180.

Think about that for a minute - that's £180 for the entire year (or £15 per month). That's a saving of £820 per year

After 10 years, you've recouped the £8k outlay. Years 10-20 you would be saving £820 per year, so you'd have £8.2k in the bank. After 20 years that's a net position of being over £16k better off than the baseline position - and that's before you add interest on those savings.

And all the above doesn't take into account beneficial tariffs like Octopus Cosy where you can get 3 off-peak charges per day 🤯 - which would make this even better - especially if your consumption is driven by a heat pump

Now I know this is "man maths" and based on known knowns like export tariffs, and it doesn't factor in replacement kit over time, but neither does it factor in price rises in electricity costs or reducing costs of solar & battery. It also assumes only a 50% offset of peak rate consumption. The more you increase your consumption from the battery or solar the better it will get.

Bottom line - if you want to reduce your household running costs it makes more sense to have solar & battery rather than money in the bank, and it only gets better the more you use it.

QrizB

Primarily the solar savings are based on a 6kwp array and £12k - and a 6kwp array doesn't cost £12k

....

Solar & battery - The market price for 5kwp of solar is around £4k, and a 10kwh battery is around £4k fully installed (I know it varies depending on complexity etc - but this is the market price). So a 5kwp array & 10kwh battery should cost around £8k

That's an interesting hypothetical, but that's not the quote the OP has asked for an opinion on.

The OP has quotes of between £11k and £12k for 6kWp and 10-15kWh of battery. Those are the quotes we're commenting on.

Martyn1981

To the OP, unless I've missed it, I can't seem to find info on location and roof orientation. It's just that a generation figure of 5,011kWh from a 6.79kWp seems a bit low.

From the first installer info, I take it your location is Yorkshire(ish?), but that should still mean generation closer to 6,000kWh pa if south facing install. Could you confirm the approx roof orientation, perhaps it's east, west, or east & west?

As you can see from the other responses, the annual generation impacts some of the calculations, especially the value of adding batts (or not).

Cheers.

Newbie_John

@Aussie_Tips , we have a real case details and you have done the typical sales man tricks:

-lowered my gilt earnings by 10% - it should be £450 from £8k (and the capital..)

-lowered the prices, OP's offer is £12k, so no point imagining £8k

-using SVR rate for calcualtion - many people can acheive 20p or under with ToU tarrifs, OP themselves is on fixed at 18p - so using higher rate payback are quicker (27p/kWh here but with solar you are using 9p/kWh :) )

-increased OPs actual usage per day from 8.5 to 10

• in solar calculations you are using ToU tarrifs why not use the same tarrif in both? they dont need solar for ToU?
• skipping maintenance costs, over 15 years anything can happen, broken inverter, battery can die, fire..
• bringing "price rises" - all i hear is gov talking about bringing the prices down..
• reducing costs of solar.. irrelevant here once you onstalinstall
• notnmentioning that export rates can go down? theyre very likely to do so
• expecting solar and battery to last 30 years, all of us to live 30 years, be at the same house for 30 years

You've showed that after 10 years money in savings is better - it changes around year 13 - so its like saying invest £8k now so in 2040 you can start saving on electricity.. 😎

There are cases where solar can work out better - but thats not OP situation,

QrizB

To the OP, unless I've missed it, I can't seem to find info on location and roof orientation.

OP has said:

also i live in east midlands

Aussie_Tips

https://forums.moneysavingexpert.com/discussion/comment/82079432#Comment_82079432

The Ops quote is frankly a rip off. So doing a calculation based on an inflated price doesn't help them

You also have not taken into account that whilst the Op is getting interest on their savings, they still have to pay there electricity bill. That erodes the savings.

And finally, you haven't considered the battery in your calculations. Through energy arbitrage the Op can move 60-70% if their daily usage to the battery. This alone will reduce their bills dramatically as they'll move that consumption from peak rate to off-peak rate.

As such a more realistic calculation was used to show savings can be made

QrizB

The OPs quote is frankly a rip off.

However, those are the quotes they've got. There's no point calculating rates of return on quotes that don't currently exist.

You also have not taken into account that whilst the Op is getting interest on their savings, they still have to pay there electricity bill. That erodes the savings.

I agree that using the income from your investment to pay your electricity bill will reduce the opportunity for compounding, and (in this particular case) will result in your capital losing value due to inflation. But in the T41F gilt example quoted, the capital is protected. For every £974 you invest today, you're guaranteed to get £1000 back in 2041 (which will be worth about £640, if inflation averages 3% pa over that period).

And finally, you haven't considered the battery in your calculations ... they'll move that consumption from peak rate to off-peak rate.

OP currently has a single rate tariff, so there's no off-peak period. Yes I accept they might be able to switch to a time-of-use tariff (that's why most of my imported electricity is charged at 8p/kWh) but the marginal savings aren't huge.

And here my usual warning: you can't choose a 15-year fixed-rate tariff. They aren't on offer. There's a significant risk involved with making long-term investment decisions today based on electricity prices they are only guaranteed for the next twelve months.

Which brings me to another point: OPs current tariff is "Fuse Aug Single Rate Fixed (13m) v3" which (as it's not yet August 2026) was offered in August 2025. It's only got two months to run. No-one is currently offering a conventional fixed tariff at 18.63p/kWh; the cheapest current Fuse fixed tariff in my region is 25.55p/kWh, for example.

Nevertheless I still don't see a case for the OP to buy a battery at this time. They don't use enough electricity.

debitcardmayhem

Here's johhny my take

Assume 12k 6kWh gen 3300kWh consumption equal split monthly for ease, and that the OPs fix @18+p

Fuse

3300kWh @ 18 +p £615

Octopus flux  EM

Consumption 3300

Generated 6000

Import 1100@.1454 £160

Used gen 2200 £0

Export 2700 2/3peak £500 1/3 £85

Net income  £425

add £615 not spent = £1230(EDIT Error £1240 ignored £10)

put 1/12th away £102.5 monthly

at say 5.25% pa (no tax)

After 10 years £12250 and still have PV + battery

after 15 years £18500 and still have PV + battery

Newbie_John

https://forums.moneysavingexpert.com/discussion/comment/82079559#Comment_82079559

I would say your calculation are "in best case scenario" my ones are more on a safe side. Either way, if they spend £12k or £8k they wont earn a penny in 10 years time.

With their low usage they could have free electricity for 15 years investing in T41F or 30 years investing in T56 (yield close to 6% now). They dont need to worry about moving houses or any issues with hardware, they dont need to be awlays on top getting best export tarrif, use more electricity when its sunny etc. Continue as they did. Very simple example.

Soon their tarrif expires and their costs will go up, but they can currently pick up exisitng ToU tarrifs: EDF free phase, Agile, Cosy, E7 etc. and act like they would have solar - run dishwasher, washing machine etc. when its cheaper. Im averaging at 17p/kWh now with this approach, should be much less in winter when A2A kicks in - and lack of sun doesnt affect me.

We're talking here about 10+ years investment and there is so many unknowns, if all "gas wars" end, price of electricity gets detached from the price of gas then electricty price should be much lower in the future, if we get another war somehwere then it can be higher. And the export rate, sadly I only expect here a downward trend..

Their usage is too low for battery need, their knowledge currently too low to make solar a worthwhile investment, but I would see them as a great candidate for plug in solar - £400 cost, they use 8kWh a day - so decent amount should be paid back much quicker… and spend the rest on gilts 😎

Newbie_John

Also this is a basic - good calculator Investment vs Solar:

https://www.jonathantracey.com/solarvsinvestments

Obviously a lot depends on variables we put in, but you can see that all the "savings" happen far in the future.