Solar payback time justification

Thanks for your replies guys. I’ll give a bit more clarification. We’re in Northumberland. The projections from the installers do state that the system should generate about 3400kw per year which is very close to what we use. But even with a battery that doesn’t mean it’s necessarily available when we need it due to obvious daily fluctuations.

The system is 10x400w panels, GivEnergy 3.6kw Gen2 hybrid inverter and GivEnergy 9.5kw/h battery, 10 Tigo optimisers (rather annoyingly, the neighbour won’t demolish her house to help with shading) and bird protection - pennies over £10k.

It’s a good point about future energy costs. I’ve seen some fixed rates of 72p per kw/h! Horrific. But part of me thinks they must surely some down again - such a high price can’t be sustainable.

We do have an EV, hence we’re on Octopus Go Faster. But our first generation Andersen A2 charger doesn’t have any Solar integration. (Yes Mrs Upnorth, I know it looks nice). I guess we just need to pay a bit more attention to the weather and manually charge it during the day where possible, or bite the bullet and get a more solar friendly charger.
 
theone8181 said:
As others said though not too bad. If you factor in a new investor every 10 years, what's your payback time?
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I think it was 8 years, but we get FIT payments of £700-750 a year on 3200-3500 kw generated on a 3.5kw system.
We don't benefit from the electric to use as its a rental property.

We are guaranteed the FIT payments for 20 years though.
 
Troop said:
Yes, over 9 years is OK, heat wave just finished it off, fitted on the gable wall in the loft, hate to think what the temp was up there at the time.
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That's actually one of the main reasons we had ours put in the wasted cupboard above the stairs*, it was an easy cable run to the loft and the CU (we'd already got cables running in ducting for the network etc), and we thought putting it there would also make it much easier to fit, and keep it at a more constant temperatures given our loft goes from "it's almost as cold as outside" in winter to "shut the blast furnace door" in the summer.


*It's a silly built in thing that you have a 50cm step up to access so it's only ever really been used to store things like christmas decorations that are too fragile/can't cope with the temperature changes in the loft.
 
Troop said:
I think it was 8 years, but we get FIT payments of £700-750 a year on 3200-3500 kw generated on a 3.5kw system.
We don't benefit from the electric to use as its a rental property.

We are guaranteed the FIT payments for 20 years though.
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That must be at the original 40p/kwh surely?
 
Yes. Not for me.

If I was in a long term house or my energy wasn't cheap it might be different. But I'll never see the gain before planned move now
 
413x said:
Yes. Not for me.

If I was in a long term house or my energy wasn't cheap it might be different. But I'll never see the gain before planned move now
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I know we’ll probably never move again now but totally agree - I probably wouldn’t consider it if there was a chance of moving. I’d be surprised (but happy to be proved wrong) if a houses’s resale value increases by the same amount as the solar cost.
 
upnorth said:
I know we’ll probably never move again now but totally agree - I probably wouldn’t consider it if there was a chance of moving. I’d be surprised (but happy to be proved wrong) if a houses’s resale value increases by the same amount as the solar cost.
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Yeah it might start to now. But it's a big gamble without evidence
 
upnorth said:
The projections from the installers do state that the system should generate about 3400kw per year which is very close to what we use. But even with a battery that doesn’t mean it’s necessarily available when we need it due to obvious daily fluctuations.
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Unfortunately solar is quite inefficient in that respect, very much more so if you don't have a battery*.

It tends to generate a lot of energy in spikes, during the day and also in the summer. So out of that 3400kw you might only benefit from maybe a third or a quarter of that, it very much depends on your usage.

*Not to say a battery is always the better option, because there is of course the quite significant added up front cost and limited lifespan.
 
1000 units per year benefit? Pay back would be 200 pounds a year!

It can't be that low surely?

I guess at 50p a unit it would be 500.but still way too long
 
Scary as a lot of people will be making savings like that but have been conned into buying an 8 to 10 grand system that they'll never repay in their lifetimes. Whereas I'm saving that many units in 6 weeks alone.
 
413x said:
1000 units per year benefit? Pay back would be 200 pounds a year!

It can't be that low surely?

I guess at 50p a unit it would be 500.but still way too long
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Without a battery possibly.

It vastly depends, if you got 3.4kw system, and didnt work from home, I reckon you'd only get about a third/quater of that of usuable electricity. That being said 3.4kw of solar panels would not be 10k, youd be looking at 5-6k (ish).

3.4kw system but say you and your partner both work from home, put the dishwasher on etc during the day, obviously now you are making more effecient use of that. Add a hot water diverter, and now maybe you are using half, or more. 3.4kw system with hot water diverter, even at say 35p per unit thats around £600 a year, now thats a 10 year payback. Also energy prices are only going to go up and that doesnt factor the saving on whatever you'd heat your hot water with otherwise (gas or heating oil) etc.

You see, how it can vastly depend on usage.

A battery changes the dynamics completely. Again, its not always the best option, it depends on circumstances and usage etc.
 
I agree - without a battery it wouldn’t make any sense for us to invest in solar. I think for some people a combination of Octopus Go and a battery is actually more worthwhile than having any solar at all.
 
For us it makes sense as we use 6500 per year and can use it to heat the water etc... I think it will pay for itself and especially when the prices go up the return accelerates. Having a battery is a no brainer IMO especially if you can top it up on a low tariff at night for example.
 
Freefaller said:
For us it makes sense as we use 6500 per year and can use it to heat the water etc... I think it will pay for itself and especially when the prices go up the return accelerates. Having a battery is a no brainer IMO especially if you can top it up on a low tariff at night for example.
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Definitely a great idea to heat water; unfortunately we have a combi boiler so no stored water.
 
upnorth said:
I agree - without a battery it wouldn’t make any sense for us to invest in solar. I think for some people a combination of Octopus Go and a battery is actually more worthwhile than having any solar at all.
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It's really down to budget that people have as well, and how that budget is used. Lots of solar installers are now seriously taking the pee with the prices for install/setup vs the real material costs, especially now the VAT has been removed. Its becoming beneficial to forgo a MCS certificate for export, and just get the DNO G98 certificate for under 3.68kW PV and do without the actual SEG payments. You can save a fortune going to down the route of competent installer, with relevant electrical safety sign-off, and just letting the excess be stored in your battery or go back to the grid with zero payment.
 
Journey said:
It's really down to budget that people have as well, and how that budget is used. Lots of solar installers are now seriously taking the pee with the prices for install/setup vs the real material costs, especially now the VAT has been removed. Its becoming beneficial to forgo a MCS certificate for export, and just get the DNO G98 certificate for under 3.68kW PV and do without the actual SEG payments. You can save a fortune going to down the route of competent installer, with relevant electrical safety sign-off, and just letting the excess be stored in your battery or go back to the grid with zero payment.
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Totally agree but so difficult finding tradespeople to do it. Actually right now it’s difficult finding tradespeople for ANYTHING!

Since posting this, I’ve priced up as best I could the actual equipment costs for my Givenergy based quote. It comes to roughly £7400 and the quote is pennies over £10k. A moot point though in this case as I think the Givenergy warranty is void if the installer hasn’t attended one of their courses.
 
upnorth said:
Totally agree but so difficult finding tradespeople to do it. Actually right now it’s difficult finding tradespeople for ANYTHING!
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I can be difficult, but things are starting to calm down now and with the cost of living rising and interest rates on the up, it is helping availability somewhat. I've had a few trades people who I left details with ages ago, actively reengage and ask if I was still looking to have work done, when most of them wouldn't even come out and quote.

Best thing to do is literally look for fitment only if you are going that route as well, design and source all your own kit, do the G98 form, and just get the ball rolling.
 
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