Well yes on the storage.
The office portion of the shop has in-floor heating. Its made up from 6" of concrete so it stores heat nicely. The shop however was built before I gathered much wisdom and knew nothing of efficiency. However the shop is full of machinery that do hold some heat. If the heating is shut off for a long weekend in cold weather I've never seen it below 5 Deg. C.
Here is a photo of the ceiling air handler that is already plumbed for the solar hot water. I believe that the solar hot water may even thermal-syphon we may require only a slow running fan motor.
And a photo of the manifold for the concrete in-floor heating. Originally the in-floor heating was done with an oil-fired hot water heater. It was fabulous. Many times I would see my secretary with her shoes off warming her feet directly on the floor.
As I had mentioned financially it isn't making any sense to install this solar hot water being heating the shop with the home-made Geo thermal is so economical, But we're on a roll.
As storage goes I do have another additional option. The original 1000 gal fiberglass storage oil tank that once supplied my home is slated for removal. One could have it spray-foamed and buried again for storing hot water.
We'll have to consider that a little longer.
Randen