Solar Panels Quoted Today

[brianixon]

Opinions and relevant comments please.
Midlands, Oxfordshire, Northamptonshire area.
Quote was for 9 panels, 6 Kw battery and inverter. All fitted and tested.
Total cost £15,000.
Assuming 15p per Kw feed in reward, on our usage a 7+ years to pay back. Which is the highest available. The salesman said.
Payment outright.
So Finance would add to costs, and calculations would be complicated by an extension, electric vehicle charging or adding underfloor heating. These would reduce our surplus. But we would consume 'our' electricity. Not buy from a company.

My own random thoughts:- Battery Capacity seems small and battery life?

I need to research panels and their output and technology of battery. Are there alternatives?

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Updated by MNHQ
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@user18 Thanks for the reminder about balance.

It’s so tempting to go for the most you can have but there’s no point if you don’t use it all. We have a 5.8kw system and and 8kw battery and solar immersion and I was exporting by 2pm yesterday at the beginning of April even though I was running the electric aga, the tumble dryer, a dishwasher and I turned on an electric towel rail just to try to use the electricity.

We have 11 panels, 15kw battery with an optimiser and paid 14k

We are on octopus flux- it is great

Charging costs are 20p a unit between 2am and 5am, 33p rest of the day apart from 4pm and 7pm when it is about 48p

Selling though is 10p between 2am and 5 am, 23p rest of the day and 36p a unit between 4 and 7

We use about 8kwh a day.

We sell anything above 50% in the battery back to the grid between 4pm and 7pm at 36p a unit. We get through the night and usually have 20% left in the battery in the morning. It then charges again during the day and rinse and repeat.

If the weather is naff we charge it to 50% in the night between 2am and 5am

The main thing we have to do is to make sure we check the weather and plan accordingly but even in winter by charging at the 20p rate we will be saving half on our electric bill.

@forgotmyusername1
Thank you for that post. I shall look more at what is available to us in terms of 'selling to grid'
What did you calculate your payback time as If I may ask?

We were told about 7 years but hopefully with taking advantage of the payback rate it may be more like 6

This week we have imported 3.5kwh and sold 33 so if we can have a decent return in summer and put it towards our winter bill that is the way to make these work for us. Obviously in the winter we won't be selling much if anything so it will be more about importing on the cheaper night rate than selling back to the grid

Thanks for the info.
I must check if the 'sell' rate is still available to new contracts.

Just be careful. Most of the tariffs offering higher sell rates also have higher import rates. During the winter you will therefore have higher bills than you would otherwise have had.

Our import rate is 20p between 2am and 5am
Sell rate is 36p between 4pm and 7pm

It makes sense to charge the battery at night and sell it back to them at peak time

yes but in winter you need that battery charge yourself so you wouldn't be selling it back. And in summer you don't need to pay to charge your battery since you're able to charge it from solar.

They may well work if you're able to be very careful with your scheduling and you're low users. I don't think they would work for us. We are quite high users and so even if we could charge the battery at 20p (saving 17p per kwh), the fact that we are paying 20p more per KwH to import year round would, I suspect mean we were worse off. Its well worth sitting down and doing the maths though for your own particular situation. Location makes a difference too since different areas have different rates.

I am not understanding your post

If we didn't have solar we would be paying 34p to use solar from the grid

Because we do even in winter when not getting enough to sell back we can charge the battery at 20p a unit and use that so saving 14p a unit on electric.

You're saving 14p on the standard rate. But the flex tariffs generally have a much higher standard rate.

So with my current supplier my standard rate is 35p per unit

With octopus flex, my low rate for charging would be 20p per unit for a period of 2 hours but the standard rate is 35p per unit and the peak time rate in the evening is 46p. So it all depends on when you are using your electricity and how big your battery and inverter are

We charge the battery at night if the following day is grey so last night charged to 70% on our 15kwh battery at 20p rate. We could have not sold back to the grid yesterday but decided to sell at 36p yesterday eve and buy it back at 20p overnight.

If the following day is due to be good we will either not charge at all or will only do a small charge to make sure we aren't using premium grid rates.

Last week we imported 4kwh through the whole week and exported 42kwh at the 36p rate. The imported hours were when our usage was higher than the max battery export and solar combined.

The plan is to use export rates now to get a large credit balance on the account for winter when we need to import more.

The way I see it

Last night we imported 7.5kwh which cost us £1.50. This is 50% of our battery (which with the bit we had left over took us to 65%)

If we sell 4kwh back to the grid (27%) we are covering what we imported last night due to selling back at 16p a unit more than we paid for it.

So that is the plan with today's grey weather. Our current battery is at 63%. The panels are covering our usage but nothing really extra so say come 4pm we have the same 63% left in the battery and after cooking dinner maybe 58%. Sell 27% back and we cover our import from this morning and still have enough to get us through to 2am charging time. Essentially we can get 3.5kwh electric for free just by shifting when we charge and discharge the battery and if the weather is good we just don't do the charging bit. Our average daily usage before solar was 8kwh so we are medium users.

It makes all the difference if you are low users and your battery capacity and inverter capacity have a significant impact on the cost benefit analysis. We use about 25kwh a day in the winter so much much higher users. For us it’s about maximising what we generate so timing appliances etc and having a solar immersion so that it also covers hot water.

Ah fair enough

Our battery storage lasts nearly 2 days of our standard usage so we can maximise the flux rates. If you are very high users then you won't be able to charge enough during the 3 flux cheap hours to likely make it work for you.

Thank you for contributing. You helped us decide. Very helpful.
Decide not to go ahead at this time, first we will do a simple extension to give us a utility room.