Is it cost efficient to link immersion to solar pv?

gerbill

We were thinking of installing solar pv and linking this to heating the immersion when there is excess energy. One electrician had advised this may not be cost efficient. I think the total outlay would be covered within 5 years.
Any advice out there?
Thanks.

cypher007

been looking into this myself.


it is cost effective, but like you say may take several years to re-coupe depending on how mental lecy prices get.


you will get paid a FIT rate on 100% of what you generate at £0.149 and 50% of what you generate, regardless of if its used or exported, at £0.046. so its a win win currently, though theres nothing to say the energy companies wont insist on export meters in the future.

thenudeone

It can be, as long as you use an intelligent switch to automatically vary the amount of energy used by the heater as the amount of spare PV changes due to weather or home electricity usage. There is a huge thread here https://forums.moneysavingexpert.com/discussion/4152489

Without an intelligent switch, you will almost certainly end up buying in a lot of expensive rate electricity, which is probably the most expensive way to heat water going.

cypher007

thenudeone wrote: »

It can be, as long as you use an intelligent switch to automatically vary the amount of energy used by the heater as the amount of spare PV changes due to weather or home electricity usage. There is a huge thread here https://forums.moneysavingexpert.com/discussion/4152489

Without an intelligent switch, you will almost certainly end up buying in a lot of expensive rate electricity, which is probably the most expensive way to heat water going.

yes you need something like an imersun.

Cardew

Agreed, an immersun type device is essential for diverting to an immersion.


When considering the cost effectiveness, savings depend on the fuel you use to heat your Hot Water tank.


Very few people use full daytime rate electricity to heat hot water. It is generally gas, oil, LPG or Economy 7 off-peak electricity.


The other point of consideration is the inconsistent nature of PV generation. Some sunny days you might have more surplus electricity than the immersion can use; other days(like today) nothing will be diverted.

Pincher

You should use an open vented cylinder, preferably a thermal store. It's a failsafe approach, so that if something fails to stop the heating on a sunny day, and the water boils, it won't blow. The cylinder output must have a thermostatic mixer to prevent scalding.