Hi Neil

No, sorry that wouldn’t work.

A fantastic way of powering a solar heating system without using mains electricity is a PV-powered pump.

This has been used to great effect, and with the added benefit of the pump only engaging when enough sunshine to heat the solar tubes is hitting the PV panel too.

I’ve seen this used to great effect with a flat-plate system and will work with tubes too. However, I haven’t seen how they fix the PV to the tube system, so you’ll have to engineer a solution. Here is an example:

http://www.discreteheat.com/thermatwin/products-and-information/what-is-thermatwin.aspx