Solar Immersion

The benefits of using Solar PV energy to power your immersion

Nobody likes to give anything away for free! So, although you are getting paid for generating Solar electricity and for pumping it back onto the grid, wouldn’t it better if you got the benefit of all that extra power you created?

There are several systems available on the market that you can connect to your immersion heater that will direct the excess power that you generate to producing hot water for your family to use instead of importing it back to the grid. You still get paid for the generated energy.

Studies show that the simplest way to cover around 57% of your home’s water heating is to divert the excess that you Solar PV system to your immersion heater.

We’ll try to do the math for you!

Calculating the payback is a little complicated but there are some assumptions that we can make;

• During the Summer months when you will generate the most from your Solar PV system, the primary heater for the water (gas/oil/wood) will be switched off and electricity will be the main if not the only main source of energy.
• The average home with a 4kWp Solar PV system will export to the grid roughly 50% of this over the whole year.
• A 10-minute shower will consume around 1.5kWh of electricity. (9kW electric shower)
• ​A standard hot water tank is 150 litres and will consume around 8.75kWh to heat up to the required temperature.

An average 4kWp Solar PV system should produce up to 25kWh on a good day. This should be more than capable of providing all the hot water you would require. There will be times when you will not generate surplus and days when you the water in the tank will be hot enough.

There are plenty of variables that can fluctuate the above, from the number of showers taken and how long the shower is running, the capacity of your immersion tank, how sunny it is, the size of your Solar PV system, etc., that make it near impossible to come up with a proper financial assessment, but….

If we look at the average Solar PV system generation for the Summer months (April through to October, when the heating is normally off.) a 4kWp system should average around 16kWh per day, exporting around 8kWh. If all this extra is used, valued at say 12p/kWh, this will equate to a saving of around £150.00/year.