Solar panels payoff calculation

Cardew

wonderman wrote: »

old. Overall total FiT plus oil and electricity savings over 12 months will be close to £1k.

Based on what assumptions please?


i.e. kWh generated, FIT rate, oil and electricity savings?

marcus_h

captainhindsight wrote: »

Hi not many people know this but because your house is heated by electric and if you meet the criteria for the affordable warmth part of eco (this usually pays for free boilers) you can qualify for a grant to help pay the cost of solar pv (probably around £2000) because it becomes a part of your heating system. So may be worth looking into depending on your circumstances.

That would make a real difference. Is this part of the RHI?

wonderman

Cardew wrote: »

Based on what assumptions please?


i.e. kWh generated, FIT rate, oil and electricity savings?

Dont have the exact figures but roughly £700 FIT, £200 oil saving and £100 electricity saving.
Its about 14% pa ROI.

captainhindsight_2

marcus_h wrote: »

That would make a real difference. Is this part of the RHI?

No its separate from rhi its called energy companies obligation or ECO it's the same scheme that is paying these 'free' boilers which you've probably seen advertised. What you need is a green deal provider as they are the ones who have access to the ECO money. You will still receive the full rhi payments. The criteria is that you have to be in receipt of certain benefits and it has to be a recommendation on an epc and for solar pv your have to have electric heating to qualify.

marcus_h

Thanks for that - what sort of benefits do you mean?

Cardew

wonderman wrote: »

Dont have the exact figures but roughly £700 FIT, £200 oil saving and £100 electricity saving.
Its about 14% pa ROI.

You haven't stated what output your panels generate; but a 4kWp system could generate between 3,000 and 4,000kWh. A good average would be 3,500kWh.


At 14.3p/kWh that would produce £500 from FIT plus a further 1,750kWh @ 4p = £70.


Oil costs approx. 6p/kWh - taking into account boiler efficiency - say 7.5p/kWh. Thus for your immersun to save £200pa it would need to divert approx. 2,700kWh of your output to the Hot water tank. IMO that isn't feasible, especially as you believe you can save a further £100 from electricity.


That would of course mean that all your generated electricity would be used in the house and none exported, and even then your savings would be well under £1,000.


Those with gas CH would save less; as would those using all electric as they would be on an Economy 7 tariff paying around 6p/kWh for off-peak electricity.

captainhindsight_2

marcus_h wrote: »

Thanks for that - what sort of benefits do you mean?

It's things like pension credit, child tax credit a full list can be seen here

Fred56

A bit late but I'll add my contribution. This is not theory, it's based on actual experience.
We have a PV system which is two years old. We get the original higher rate os FiT.
Anyone considering a PV system should ignore the sales patter and listen to fact. In terms of using the output yourself do not bank on a high utilisation. We are energy savvy, I designed and built our super-insulated home and we know how to use it. We are at home all day and try as best we can to use the PV output. Hence, the washing and baking a saved for sunny periods. We use a slow cooker and minimise electricity use when it's dark or overcast. At best we manage to use a little under 50% of the PV output. We can measure it because the smart meter shows us the export.

Inverters - a future scandal just waiting for the media to discover it.

Inverters are trash. We have had one failure already and research shows that we are anything but unique. The inverter is still in warranty but we instantly see the manufacturer quibbling. When I say manufacturer, this is indirect as the original manufacturer went through but was bought out by another. Their tactic is to try to deflect blame onto the incoming AC supply (based on absolutely zero evidence) even though internet research shows that these devices have been failing since 2011 which is before we got ours. It does not take a genius to calculate that in a few years years out system will be beyond economic repair due to repeated inverter failure. Once out of warranty it will be the going rate for the device, currently £800 ish plus labour at £400 a man day (what we originally paid) all plus VAT. That swallows more than two years of FiT but if the inverter fails every two years it's a net loss.

Inverters are not certified by the MCS, they just need a G83. No come back, supplier and manufacturers will just disappear in a puff of limited liability. Insurance, just wait for the premiums to spiral.

Who is responsible for our inverter? The sainted SMA who must have the world's most proactive PR department.

Cardew

Fred56 wrote: »

A bit late but I'll add my contribution. This is not theory, it's based on actual experience.

At best we manage to use a little under 50% of the PV output. We can measure it because the smart meter shows us the export.

Inverters - a future scandal just waiting for the media to discover it.

Inverters are trash. We have had one failure already and research shows that we are anything but unique. The inverter is still in warranty but we instantly see the manufacturer quibbling. When I say manufacturer, this is indirect as the original manufacturer went through but was bought out by another. Their tactic is to try to deflect blame onto the incoming AC supply (based on absolutely zero evidence) even though internet research shows that these devices have been failing since 2011 which is before we got ours. It does not take a genius to calculate that in a few years years out system will be beyond economic repair due to repeated inverter failure. Once out of warranty it will be the going rate for the device, currently £800 ish plus labour at £400 a man day (what we originally paid) all plus VAT. That swallows more than two years of FiT but if the inverter fails every two years it's a net loss.

Inverters are not certified by the MCS, they just need a G83. No come back, supplier and manufacturers will just disappear in a puff of limited liability. Insurance, just wait for the premiums to spiral.

Who is responsible for our inverter? The sainted SMA who must have the world's most proactive PR department.

Excellent post!


IMO there are far too many unrealistic claims of savings and a blind faith that nothing could possibly go wrong, in 20 years, for panels bolted on a roof and their associated electronics.


In a year or two the majority of solar installation firms will have moved to pastures new, and guarantees will be as worthless as many others have been in the building industry - dry rot, damp course etc.

Smiley_Dan

We use 85% of our generated electricity (4kWp). But that's largely down to an Optimmersion and an optiplug powering a heater. Would do the same with 8kWp I think.