Solar panels linked to immersion heater

annclem

My array of  8 solar panels is linked to my immersion heater. I see that the immersion heater switch is switched on. Does this mean that the immersion heater will be using electricity from the grid when there is no solar power. 

Le_Kirk

Depends upon how it is wired but one would assume that would be the plan - otherwise, cold showers!

Heedtheadvice

Plus it depends upon how they are controlled!

Long answer:

If it is just by a manual on off switch (that you mention)?  then you likely will want to only switch it on at a time before it is required as heating via electricity from the grid is relatively costly so do not waste heating when it will not be needed. Sometimes that is difficult to predict.

It may be that it is on a time switch for pre-programmed control?

 

You might have installed what is commonly called a  such as an Immersun, Iboost,Eddi etc. These aim to effectively switch on the Immersion heater when you have excess generation that is not being used in your property. I.e. lots of solar generation don't just export it but use it to heat your tank. That normally relies upon you manual switch being on but it does not mean you import from the grid potentially all the time.

What you have and how you use it depends upon the above plus if you have other heating sources such as gas or oil or a heat pump.

Irrespective of what you have 8 panels will not be good enough to heat your water all year round so if you rely on your immersion heater you will need to buy electricity at times of poor solar generation such as times of darkness, many a winter day, how much other electricity you use and how much hot water you need!

Short answer: maybes aye, maybes no.

If you do not have one of the smart divert controllers it might be worth considering having one installed, if you can afford it and don't mind having that money tied up for a few years until it has paid for itself. Install cost are in the hundreds of pounds.

annclem

I have an immersun fitted. I know that there’s not enough solar power especially in Northern Ireland but I think there should be in the summer months. Thanks for the comprehensive reply. 

Heedtheadvice

Ah, so the short answer is now: you will only be using any excess to heat your water via the immersun ....if the immersion is connected via the Immersun and you have it set up to divert excess to the Immersion.

Of course if you also have the Immersun set to boost (on demand short term periods) or have it set to programme immersion heating on a routine basis then that will draw power from the grid if solar by itself is insufficient. That will only be the balance between what the solar provides at that time (might be zero or up to virtually all solar generation) and what the immersion heater's power rating is (until the thermostat cuts out when water is hot enough).

I am in a similar geographic position to you and in the present weather we get loads of excess generation. We currently generate about 25kWh per day from 16 panels. These are south facing and not shaded. You should (if similar orientation and no shading) generate approx half that amount and over the year about 1800+ kWh. If you have your immersun setup correctly then it could provide a significant amount of hot water for you and any further excess power generation (you will probably always have some! ) could be used for other heating but that depends very much on your circumstances.

The Immersun web site or the Immersun app should give you lots of good information about what you generate (and when!), how much xs you have (Export), how much you consume, divert and buy from the grid.

Feel free to p.m. me if you need help optimising your generation/use.