Adding to my solar system

Newbie_John

https://forums.moneysavingexpert.com/discussion/comment/82103505#Comment_82103505

You havent mentioned export rates, neither import.. you have good west roof - great for Flux export - I would consider that first to lower your bills. Your usage is about 7kWh a day and your system should generate 10kWh a day in summer months so enough to cover your consumption.

If I was in your place I would consider things in this order:

1. Move back to Octopus (many tarrifs and easy to switch between them) - choose Flux for export and E7 (their ToU tarrifs are currently not so good) for import at least for sunny half of the year - run all white goods over night. Then back to normal import export for winter. This costs you £0 and should improve your earnings/spendings.
2. Maybe a cheap battery for around £2k and also play with Flux export?
3. Then lastly expanding solar, your consumption is low, costs will be high, labour, scaffolding etc.

QrizB

I can't tell which roof is yours from the image shared but if it is the one on left, you will be able to fit 24+ panels on both aspects of that
roof alone.

OP only occupies half the property (it's a semi) so I don't think this is going to fly. The current system was installed on an ECO grant at nil cost (see OPs earlier threads for details) and works well enough.

I think the OP is on the right lines with thoughts of adding panels to the flat roof. Their current system has a 2.5kW Solis inverter so adding a 800 watt plug-in system would keep them under 3.68kW and they wouldn't need G99.

Hopefully "legal" ones will appear in the shops in the next few weeks.

Screwdriva

https://forums.moneysavingexpert.com/discussion/comment/82103695#Comment_82103695

There's just no getting anything past you. Spot on @Reed_Richards, design should start from the roof but sadly, in the UK, is limited by the DNO.

Screwdriva

https://forums.moneysavingexpert.com/discussion/comment/82103740#Comment_82103740

I hope someone can highlight/ shade exactly what part of the roof belongs to them - I'm still not clear as E/W aspects were mentioned. If the flat roof is available, then that's useful. If more space on the tilted roof is available, great. A new inverter will likely be needed as the Solis inverters have 1 or 2 strings only. My point is (as you may recall from my own experience), maximizing every square inch of viable roof real estate remains very much to the homeowner's benefit.

For those who aren't familiar with my own journey: I added 8 X 550+ Watt Sharp bifacial panels to my existing roof array of 10 X 400W bifacial panels installed in 2019. My generation for 2026 will be more than double what it was prior to expansion and I am paid 16p per KWh for everything I export. (I paid ~£3K for the additional panels & optimizers). Valuing each KWh at a conservative 18p per, that's well in excess of £1400 this year alone with no battery. Your milage may vary.

Skintsaver

Not the best images but as mentioned above I'm on a Semi Detached.

The suggestion of moving the existing to the flat roof and replacing these with a higher output is interesting idea.

A battery is probably the best for now, I've moved my export to Fuse so I'm currently receiving 13p for every thing I export to Fuse. And import is with outfox the market with a very good rates.

My goal would be save money in the long run, I think simply adding a battery may be the best option, though I'd like my generation to cover the dishwasher ect... So the 800w plug in would be a good idea, could you have 2 of these on your house?

QrizB

@Skintsaver I recall that back in 2022 when your panels were installed there was some confusion over exactly what you'd been given. Did you get a satisfactory answer from your installers?

Your current ones were installed for free. What's your budget for improvements?

So the 800w plug in would be a good idea, could you have 2 of these on your house?

As the changes to the law currently stand, I think you're allowed one plug-in system per circuit but (taking into account what you've already got) if you fit more than one you'll be over the G98 limit and will need to ask permission from your DNO.

Plug-in batteries aren't currently permitted. You can buy them, and if you plug them in they'll work, but you won't be able to get DNO consent.

Newbie_John

@Skintsaver - 13p export, with Ocotpus Flux you could get double that for export between 16-19 and most of your panels face west which is great for that. You also have East so morning covered hence i recommended E7 tarrif (at least for summer) as you'll get half price epectricity between 0-7am - 13p/kWh and 31p during rest of the day - though this is offset by your panels. You're probably on 24p import all day.

Flux & E7 from March till Ocotber should work much better for you and it costs you £0.

Battery, panels etc. - wer're talking about £2500+ investment compared to your yearly £500 electricity bill (without standing charge).

debitcardmayhem

Sorry @Newbie_John but flux only combines with flux , not any others.

https://octopus.energy/help-and-faqs/articles/which-export-tariff-can-i-combine-with-my-import-tariff/

Newbie_John

Ok, then just E7 😎

QrizB

In another thread the OP is considering an EcoFlow Stream PV system with four 500W panels and a ~4 kWh battery. Something like this, currently £1650.

This could work well on his flat roof. It would need mounts; something like Console tubs might work, depending on the load capacity of the roof.

Having bought an EcoFlow kit myself I found the provided cables to be rather short (they're long enough if you put the battery in the middle of your array, which in this case would be on the roof) and had to buy some longer ones.

It would need to be hard wired and if there isn't an appropriate spare circuit already available it would need notifying to your local building control department under Part P if you don't want to violate the Building Regs. (Scotland might be different). In my neck of the woods the Part P fees are ~£500.

From looking at the ENA database I think the Stream batteries have G98 approval and adding another 800 watt system would still keep the OP's total under 3.68kW, so wouldn't need G99.

Considering the overall cost is likely to approach £3k and the VAT situation (reclaimable by VAT-registered professional installers) it might work out cheaper to get an electrician to supply & fit the kit rather than trying to DIY it.