Well, as a Process Engineer who's had an otherwise very boring day at work, I can hardly resist the lure of a magic thermodynamic box, can I!?
So, repeat after me:Heat won't pass from a cooler to a hotter
You can try it if you like but you far better notter
'Cos the cold in the cooler with get hotter as a ruler
'Cos the hotter body's heat will pass to the cooler
Heat is work and work's a curse
And all the heat in the Universe
Is gonna cool down 'cos it can't increase
Then there'll be no more work
and there'll be perfect peace
Really? Yeah - that's entropy, man!
A quick internet search came up with this: Thermodynamic Panels from the Magic Thermondynamic Box
. The website is a little vague on the technical details, but from what I can gather, it's an air source heat pump, that also gets a bit of a leg up from solar heat gain.
Heat pumps are well established technology - you've got one in your kitchen that you use to stop your milk from going off
. The only difference between this sort of heat pump and a domestic fridge is that instead of extracting heat from the inside of the fridge and rejecting it to the black coily thing round the back, you're extracting low grade heat from the outside air, sort of magnifying it, and then rejecting it into your water cylinder.
The 'magic' (hint: it's not magic) thing about your nifty box is that instead of just extracting heat from the air, it also catches a bit of solar energy and extracts the heat from that too.
So yes, both of these are well established technologies. As to whether it's the right thing for you, that's another matter.
If it were me, I'd be looking at how I heat my water at present, and would then try to make an estimate of how much that costs me per year. Then I'd compare that with the cost of the magic box, and its running costs of £100 per year (I'd want more evidence before trusting that figure too much though!)
Air source heat pumps typically have a coefficient of performance of roughly 3.5 (i.e. for every unit of electricity you put in, you get 3.5 units worth of heat out). Some are a bit better than that, and some are worse, but that seems to be a reasonable figure for estimation purposes. What that also tells you that no matter how magic the box is, the best it can do is reduce your energy consumption by about 2/3 compared with just using a standard twenty quid immersion heater. Also, if you're already using something cheaper than electricity to provide your hot water, you may not actually save money, especially once installation costs are taken into account.
So in summary, yes, it's well established technology. However, whether it's right for you, will depend on your own circumstances and the overall cost of installing the system.
We went through a similar exercise recently for another type of renewable system, and TBH I was seriously unimpressed with the downright lies told by some of the salesmen. Their calcs showed us being £35K better off over seven years. My honest-as-I-could-get-them calcs made it nearer £800. Caveat emptor!
So, I hope that helps! If not, it brightened up my afternoon at least!