Is solar battery storage worth it?

CuparLad

Not yet built, but say 15M?

Martyn1981

CuparLad said:

Not yet built, but say 15M?

I don't know if this is quite the same, but I recently had a PV ground mount installed, and the panels are ~15m from the existing inverter, that they were added too. No problem, and I wasn't aware just how small DC cables are.

As I have a Solaredge system, I can monitor all my panels (30 with 22 on that inverter) individually, and the ground mount is operating fine, and as expected ...... so far.

Heedtheadvice

That sort of distance is of little concern. Just make sure you use cables of a substantial cross section area of conductor to keep resistive losses minimised and suitable for buried DC applications.

Although it is usual to use the solar type of waterproof connectors throughout they will not be necessary for any continousl run that is not exposed to the elements. Junction boxes ( internally if possible) can be used so that heavy duty cable can be used for the run from house to garage. Bury it in conduit for added protection and quite deep ( forget the actual depth for the moment ) and use coloured sheath cables to enable easy polarity identification. 10mm sq. cable would be great.

Please note though that this response is not definitive as there are regs for underground buried cables and possible PV protection needs but they should be covered by any competent installation designer. There will be plenty of electrical companies competent in a rural area such as yours.

Similar needs will be required for mains cable installation to/from your 'power house'

QrizB

I'm going to tag @Telegraph_Sam in this thread as he's asked a couple of times about the economics of home battery storage.

From here:

Telegraph_Sam said:

Could I ask for some basic guidance on the economics of installing solar batteries. I did this exercise a year ago but concluded then that from a financial viewpoint the outlay could not be justified. Perhaps the metrics have now changed.

I have solar panels. 16 producing in total 4 kWp. On a 22° pitch south facing roof, North East England. Av annual kWh 3180. FIT's go to Scot Power. Deemed export now SEG's go to Octopus @ 15p / kWh.

Normal consumption is on Octopus Tracker. 945 kWh / year.

I do NOT have an EV

Normal consumption can mostly avoid the evening peaks, but otherwise load shifting is limited.

Back in April 2024 my expenditure on electricity was estimated @ £516. Allow for inflation since then.
I am not clued up on the costs / performance of the latest technology: Someone said I should look at the Musk (not Tesla) Powerwall but I don't have the tools to evaluate this objectively and scientifically
Can anyone help - or refer me to a source than can?
Tks.

My personal opinion is that you're not using enough electricity to make solar battery storage viable.

Imagine you could store electricity all year round, such that you could self-generate all 945kWh/year that you currently buy. I'm going to ignore conversion losses and the fact that the sun doesn't shine much in the winter.

• Cost to buy 945kWh @ 23p/kWh: £217
• Lost export payment for 945kWh @ 15p/kWh: £141
• Net gain: £76

A fairly basic battery storage system like this one is going to set you back £1500, plus say £300 for a day's electrician time to fit & commission it. That's £1800, so your £76 gain is about 4.2%. You'd earn more by putting your money in an ISA.

If anyone can see a way to make the maths work for Sam, be my guest!

Telegraph_Sam

Thanks for substantiating what was my gut feeling!