Tiny UFH system/Battery storage

[Big Neil]

So if i wanted to build a kids playhouse, so effectively a posh shed (but out of lets say brick and block for the sake of argument), and equip it just a simple one zone wet underfloor heating system and I was also going to give it solar panels. What setup would be best? A tiny sunamp, an ASHP with (i imagine) a buffer tank? Can one get very small ASHP units? Likewise For the battery power would you just use one of them thar Sofar systems, given it would only be a few lights, and maybe a tv and stereo. They seem to be small as I've seen mentioned in other threads.