My dreams for a Solar Powered life

MouldyOldDough

I have dreams for Panels on the (detached) garage roof - with a battery in the garage and a charge point on the side of the garage for an EV …….the garage runs N-S.

With a connection back to the house - to allow use directly from the panels as well as the battery (at night and dull days).

Our electricity consumption is low at the moment (1250kWh) and gas (5kWh)

How many panels would we need to live our dreams and be totally self-sufficient at least for electricity and running a car (5000 miles per year) ?

squirrelpie

Our electricity consumption is low at the moment (1250kWh) and gas (5kWh)

You don't say whether that is every day, month or year, or some other time. Most people's gas consumption is greater than their electricity consumption, so can you confirm?

You need to think about how efficient your EV is to give a number for its consumption. But if we assume 4 mi/kWh then it will need 1250 kWh for 5000 miles.

There's a lot more solar power in summer than in winter, so you wouldn't be able to be self-sufficient in winter. And you'd need an awful lot more space than an E-W array on a garage to cover your usage, unless it's a ginormous garage!

doodling

Hi,

5kWh seems a very low gas consumption - it's not worth having a gas supply with a consumption that small.

Assuming a car achieves 2.5 miles per kWh (so 2000kWh for 5000 miles) then your total yearly consumption would be 3255kWh.

If we assume that you are in London and consume this evenly throughout the year (this is optimistic!) then you will need a battery of around 100kWh and around 15kW peak of panels.

The latest guidance suggests that the largest battery that should be installed in domestic properties is 80kWh. 15kW peak of solar is an absolute minimum of 54m2 of panels.

[ Edited to add - that is 54m2 of South facing panels at 35 degrees - you will need roughly double that if you have a North/South ridge. ]

I hope you have a big garage and a friendly insurance company!

On the plus side, you will have phenomenal amounts of spare power in summer...

Nearlyold

We had 15 panels (5 South facing, 5 West Facing & 5 East Facing), along with 2 Batteries, and a car charger installed just under 2 years ago. So far the system has generated 9,492 KWH.

Your Potential installer should be able to calculate the number of panels you'd need to meet your requirements though your garage roof will almost certainly not have room for the number you need.

In the meantime you could look at this site:-

Solar panel calculator - Energy Saving Trust

Newbie_John

1250kWh a year that's like £300

add 2000kWh for a car and the yearly bill is £800

You won't be able to cover all your electric needs just by relying on solar, so you'll still need to buy electricity. You'll have too much in summer and not enough in winter.

So compare these values when doing financial viability..

Ectophile

It may depend on what you mean by "totally self sufficient". Averaging import and export over a year, or generating so much solar that you never need grid electricity?

Winters in Britain can be grim. Short days, and often day after day of cloud without ever seeing the sun. You're not going to get very far in an EV on the power that the panels will generate in that weather.

Alnat1

E/W panels on the garage would be fine in summer but will generate almost nothing Nov-Feb when the sun is low in the sky.

If you're imagining a "solar powered life" means living off grid, then it's not going to happen with the set-up you're suggesting. If you are happy to generate plenty in summer, sell the excess back to the grid and use the credit in winter to buy the electricity you'll need, that is a possibility if you can fit enough panels.

MouldyOldDough

https://forums.moneysavingexpert.com/discussion/comment/81871856#Comment_81871856

Sorry - gas 5000kWh annually

Elect - 1250kWh annually

QrizB

Do you remember we had a good discussion about this last year?

https://forums.moneysavingexpert.com/discussion/comment/81473442#Comment_81473442

At that time I was making some assumptions about your energy use, but we can revisit that now with your actual numbers.

Can we also assume that you'll be replacing your gas heating with an electric heat pump?

We'll then have:

• Domestic electricity: 1250kWh/yr
• EV: 1700 kWh/yr
• Heat pump: 1700 kWh/yr
• Total: 4650 kWh/yr

That's slightly less electricity than the 5000 kWh/yr we'd previously assumed you'd be able to generate from a 6kWp solar PV system installed on your garage roof, so you could be "net grid zero"; your excess generation in the summer would balance out the grid electricity you'd need to buy in the winter.

Obviously if you keep the gas heating, you'll be a net contributor to the grid.

MouldyOldDough

OK - So if I had a V2H car - that could feed electricity back into the house - would that make any difference ?

Are there any Hybrid V2H cars ?

Because at the moment - I don't feel quite ready to go full EV

MouldyOldDough

https://forums.moneysavingexpert.com/discussion/comment/81872984#Comment_81872984

Interesting - thanks worth investigating further

a minor point - the car could sit there for several days slowly charging - not used every day