Solar for off-grid house in Spain

I would like the price for a full solar energy system to be installed in Spain to run 2 small 3 bedroom houses which have just been built side by side.

The system needs to be off grid, and able to run all potential electric mod cons (though not air conditioning). Thanks, Mike.

Hi Mike,

A typical household in the UK uses around 12.5kWh per day. On a
typical UK summer's day you would need an array of around 2500W of
solar panels to generate sufficient electricity over the course of a
day to replace that power.

On the one hand you have better sun resources in Spain, and with
energy efficient appliances you can reduce the 12.5kWh needed per day
considerably; but on the other hand there will be times - overcast
days in winter - that the panels produce less than 12.5kWh per day. On
balance, a 2500W array will give you a pretty good amount of power to
play with - but you do have to remember that fundamentally a battery
bank is a limited resource, and if people leave all their appliances
on over a couple of dull winter days it will run out!

Your battery bank needs to be capable of storing considerably more
than one day's power, as it's bad for the batteries to be heavily
depleted, and also you have to have a good reserve for those overcast
days when the panels are not doing very much. As a minimum, I would
say a battery bank of 40kWh for a 2500W array.

So, the system components for each house would comprise:
- 2500W of solar panels. Approx cost £9000.
- 32 x 110Ah 12V batteries (capacity= 32 x 110 x 12 = 42240Wh).
Approx cost £2500
- Solar Regulator. Approx cost £200.
- Inverter to produce 240V AC from DC battery bank. Approx cost £1500.
- Wiring, mounting system etc. Estimated cost £1500.

So total system cost is around £14700 per household, plus installation costs.

You may be able to save 10% on that as the figures I have quoted
include VAT of 17.5% - there is a lower rate of 5% on energy efficient
installations on houses in the UK, which you may qualify for.

The cost is pretty much proportional to the size of the system. It is
perfectly possible to run a household on a system half that size (and
half that cost), with careful use of electricity. Many people in
caravans and narrowboats live quite happily with solar arrays less
than a quarter that size or even smaller. On the other hand, if you
want to be able to run everything under the sun (so to speak), you'll
find that even a 2500W array per household is not enough, particularly
in the winter.

Hope that helps - Andy