Solar + mains for electric heater

I live in a small apartment which the electricity costs sky rocket in the forthcoming winter months. My apartment is not well insulated, I want to build a solar generator for the hell of it, but I want to couple its output power to "supplement" some of the power drawn by the electric heater.

The electric heater is 1500 watt Quartz tube heater from Holmes that operates off of 115 VAC

My question is, how can you couple the solar and mains power so the solar will give some power to the heater so it uses less power from the mains

Would this work in theory? I know I can't run a 1500 watt heater off of a solar generator unless I want to spend $7000, but I may be doing this for a senior project idea, I just want to see if it is possible and it would cause my electric bill to go down

You would be far better off using the solar to directly heat your apartment. Have a look at https://en.wikipedia.org/wiki/Solar_air_heat

Mike.