Need Help New Solar 8kw Install 11 February 2021 at 10:44PM in Green & ethical MoneySaving 4 replies 239 views

Danno2k

Looking for help, if you guys have the time to help
I was looking to get installed a 8kw solar system installed at my home, but i was told if i go over a 3.68kw inverter i need G99 application 
Which is hard to get ? as your not allowed to send more than 3.68kw down the grid without this 
What would be my best option 
1, Go off grid and send nothing down the grid, if i'm still allowed to install the 8kw system ?
Not sure if you still need something still for me to install this size 
2, Go smaller and install battery's ?
I use are 7000k a year in power
Thanks

Hexane

Danno2k said:

i was told if i go over a 3.68kw inverter i need G99 application 
Which is hard to get ? 

Mine wasn't hard to get, my installer made the requests and it took a few weeks and cost me nothing. (Other than a little worrying over whether it would be approved.)

Danno2k said:

1, Go off grid and send nothing down the grid, if i'm still allowed to install the 8kw system ?

Do you really mean you want to not have an electricity supply from the National Grid at your property at all? If not, that's not going to work.

By the way, your annual electricity usage is measured in kWh (kilowatt hours).

Pile_o_stone

Danno2k said:

Looking for help, if you guys have the time to help
I was looking to get installed a 8kw solar system installed at my home, but i was told if i go over a 3.68kw inverter i need G99 application 
Which is hard to get ? as your not allowed to send more than 3.68kw down the grid without this 
What would be my best option 
1, Go off grid and send nothing down the grid, if i'm still allowed to install the 8kw system ?
Not sure if you still need something still for me to install this size 
2, Go smaller and install battery's ?
I use are 7000k a year in power
Thanks

Unfortunately, you won't be able to go off grid with just 8kw of solar panels. If I were you, I'd get the solar installer to make the G99 application. If you get it, then everything is fine. If you don't then you can look at getting your installer to fit a G100 export limiting device. This will limit your export to the grid to 3.68kw (or whatever maximum your DNO keeps you to). You may find that it caps your exports at the height of summer but won't kick in at other times, especially if you are a high user of your own electricity. So if your panels are generating 7KW on a summer's day, but you are using 4kw of power in your home then you will export 3kw to the grid without the G100 device activating. If you generated 7kw, used 3kw, then the G100 device would limit your export to 3.68, losing 320 watts.

https://www.argandsolutions.com/g100-export-limitation

Solarchaser

From everything I've read,  going off grid is waaaay more expensive and way more hassle, as you would need something making power in the winter when solar is poor.

I was a 7mwh consumer before solar, I've added an ev as well so probably more like an 8.5mwh consumer now, but with solar and batteries I'm only buying around 2000kwh at full price and probably another 2000kwh at 5p over the winter.
Batteries will help with self consumption,  as would a solar diverter to heat up your hot water tank if you have one, but.... if you are looking for a 10 year return on investment,  you will likely struggle to do that with batteries as they are so expensive to buy in the quantity (kwh) that you would need to cover the house. 

Dolor

DNO applications do take a few weeks (about 3 months in my case). I had a 7kWp array installed last September with a PW2 battery. There was a £350 application fee and the possibility of an extra fee for a witness inspection. My installation was approved with a 5kW export limit: in truth, as my panels are arranged on two roofs 90 degrees different, the limit does not constrain my output. DNO sign off post installation took another couple of months. If you want SEG payments then some suppliers are insisting on an MCS Certificate, and DNO approval. The latter is required to get an export MPAN. It looks like a simple way for DNOs to check that people haven’t been circumventing the approvals process.

I found this blog helpful:

https://blog.spiritenergy.co.uk/homeowner/dno-permission