Electric Underfloor Heating Retrofit with Solar PV

[Jayzee1980]

Hi All, I have a new(ish) build home and we're at the point we need a new floor downstairs. The previous tiles cracked due to the concrete not being perfectly flat (installed by the builder 7 years ago), so we need a floor screed before tiles (or maybe Karndean). It's a 2017 house, so well insulated.

This is now my opportunity to install electric underfloor heating as a secondary heating source; and specifically when we have excess solar generation. We already have rads everywhere on a gas combi boiler, however this is my opportunity if I am going to do it or not.

We have a large 9kw solar array, with an 8kw inverter. We can only sell at 5.7kw to the grid, so if my batteries are full and I can't make use of the electricity I lose it. I try my best with battery charging etc etc. I also run Home Assistant, so any excess I can't use would automatically turn on the heating and off as needed.

I have considered wet under floor heating with a heat pump, but it would cost a fair bit to install with raising the floor, redoing the skirting etc. Also, ASHP aren't suitable to immediate on/off, due to the start up energy required.

It also gives a good heat source if my boiler was to breakdown temporarily.

So firstly, is this just a silly idea?

Secondly, what would people recommend?

 

[Jayzee1980]

Just adding a bit more, this would be in our kitchen and hallway (for now). The other idea is when it's nice and sunny in the day, we don't necessarily want the heating. However as soon as the sun goes down, a bit of heat is required. Therefore the floor would act as a heat store to release later in the evening.

Could I put these mats straight onto the concrete base? It is fully insulated. Then add the floor screed over the top? I don't really want to add those insulated mats.