Although both solar thermal and solar PV capture energy from the sun, they each convert that energy into different forms. With PV that is electricity and with thermal that is heat. The benefit to PV is that electricity can be used to power anything in home. However, solar PV is not nearly as efficient at capturing and converting energy as solar thermal (20% vs. 60%). Because of this efficiency limitation, it does not make sense to generate PV electricity to run an electric boiler vs. using solar thermal to replace an electric boiler.