Solar PV installation in a new build

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Hi!
I’m after advice on how to simply calculate the number of solar panels I will need to power a new home I’m building in the Uk.
Roof is due south facing, angled and unobstructed.
House power requirements are for Air source heat pump, underfloor heating, normal 4 bed energy usage, standard kitchen (hob, cooker,washing machine - all electric) plus electric car charging.

How can I calculate my power requirements as not everything will be used simultaneously …but I guess they maybe!?
Help!
Thanks
David
 
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Cover the entire roof.

If you want the longer version you can find examples of people who've done the same. They never have enough solar production in winter as the heat pumps need a lot and (if they have batteries) they use every Watt and still want more. In summer they have a significant surplus to pump back to the grid.

You can use something called PVGIS to understand what your power production is likely to be per month.

Your average house uses 4,000 kWh a year, an ASHP uses another 4,000 kWh (mostly over winter) an EV doing 10,000 miles needs something like 3,000kWh.

Going for a system twice as large only costs something like x1.25 - 1.5 as much so going large makes a lot of sense

Are you going for three phase power? It probably makes sense.
 
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Agree with above, put on as much as will fit. The panels aren't the most expensive part of the job so go for the maximum.
 
You might want to consider installing batteries at the same time for solar eating, load shifting and TOU tariffs...
 
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Around 20 panels, but you will need DNO approval and you should go for an overnight EV tariff. Octopus give you 6 hours at 7.5p /kw. Combine that with battery storage system. Tesla are expensive, but they have a lot of useful features.

Also I'd look at reversible aircon rather than air source heat pump. Your house will have a U value of 0.18, so your heating and cooling requirements will be nowhere near avg.

Also look for appliances with wifi control - this will enable you to schedule based on output.
 
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