Relatively Cheap and simple 9.8kWh solar energy storage for a combi boiler

My vented boiler hot water energy storage system uses a DHW tank and a 140 Litre ‘heat store’ using an un-pressurised copper tank and an energy diverter. This has operated very successfully during the last 9 years and has diverted about 30MWh from my solar panels.

My neighbour now has solar panels and a combi boiler so to do something similar he would need to operate a pressure vessel at mains pressure to provide solar heated water to the boiler.

I was wondering if a non-pressurised approach as shown in the attached diagram would be possible.

I don’t see a problem with the suggested diagram. That said, you might find this article helpful so the appropriate type of cylinder is used -

Thanks for the comment.

The idea is to use a vented tank. This avoids the need for an expensive pressure tank.

I shall update the diagram to make this more obvious.