Using an old immersion heater as the top tank in a drainback system

[cortijo]

I found a 50 litre hot water immersion heater. I would like to use it as the top tank of a drain back system.
A pump will pump the water to the panels and then the water will come back down by gravity and also the pressure of the pump.
It looks like it may be better to have a hole in the top and the bottom of the top tank to make the water flow though it better.

Does it matter if the inlet and outlet are on the same side because this means that the water has to flow up just a little bit?

Has anyone got any experience with this.

[LucMan]

This will work no extra holes in the tank are needed, this should be a closed to the atmosphere system.
Pump should be connected to the lowest point, return from panels at the highest point.
Don't forget to install a high pressure safety blowoff.