A question asked often and also rejected as the house does not use solar just the things in it. Lets have a look at what solar your home needs.
1
Go to the smart meter and read what the kWh say at the end of the day, keep a log for about two weeks to get some general power use figures.
Not have one of these? time to do a meter reading every 24 hours.
2
Now we have our meter reading we should look at the time of day use of the power between the following points:
06:00 – 9:30 (a)
09:30 – 15:30 (b)
15:30 – 20:00 (c)
20:00 – 00:00 (d)
00:00 – 06:00 (e)
The table is as follows; a is a summer solar production time. B is a winter production total time. d is a summer production time. e is a night or charge time. c is usually the higher load.
3
A battery should cover the period from the end of B to the start of E when you will grid charge in winter.
Generally it is wise to size the battery for 1.5 days. the array size will be dictated by the battery size and the loads.
4
The power used within the times shown would be the “base load” and the minimum the solar panels would need to provide. this does not take into account that the battery will need to be charged as well.
in winter the load will be C back round to B.
Your battery will need to be charged and therefore the minimum solar duration is 2 hours in winter. you should account to charge the battery from the grid at the cheap rate or by genset.
10kWh battery 5 kw solar array would charge (not in reality) in one day where there are no loads. You would need to add 40% to charge. However you may find low rate charging a better option.
A 5kw array will provide around 3250watts of power if there is a 500wh load on the house, then there is 2750watts to charge the battery. A 5 kWh battery would charge in a little over 2 hours in theory.
5
Look for the sun.
We have a sun hours chart on our information posts, “sun hours” into the search to find out how many hours there are on average each day by the month. You multiply the size of the array to the sun hours which will give you the array size.
You will find its feast and famine with solar in the UK, so you would want to pick between the array size and costs vs grid charging.
You can mitigate some of the hard work with a solar tracker as this will boost the year round performance of the solar panels.
6
Tilt and season.
If the sun shines for 8 hours on a summers day, you can half the power by tilting the panel down so that it almost vertical. The panels will then peak at winter using the 600 NOCT information from your panels data sheet, while the summer panels may lose more than 50% power.
You will find posts and videos in respect of this on this website and our YouTube channel.
Solar is not a one size fits all and there are some compromises to have or to mitigate. RenewSolar carries out personal inspection and problems solving for clients across the UK. Many people follow the average or the information seems to be golden, when in reality it can be wrong and misleading and ruin your experience with solar.
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