Solar assisted heat pumps - night time solar

Martyn1981

Solarchaser wrote: »

I've never heard of green fund investment... and how would I buy some import. I'm a little confused.

Sorry I went straight into waffle mode.

There are green investments out there, Abundance is one of the best known. So I (this is a personal opinion, so no rights or wrongs I think) decided to pop money into solar, wind, hydro, AD schemes etc, not much, but bits and pieces, instead of chasing down small personal gains.

For instance, I'm a massive battery fan (and a fan of massive batteries), and early adopters are crucial for the industry to grow, but for myself personally I could only hope to switch around 900kWh from import to PV, and of course due to battery losses my impact on 'greening' the grid would reduce overall.

So instead, hopefully my bits and bobs invested elsewhere mean I'm 'responsible' for green generation almost 100% of the time. No idea if that makes sense, or is in any way true, but hopefully it's OK.

By 'buying import' I simply meant that you'd spend a bit more on import, v's the large capital outlay of the thermo panels, and that might actually be a better financial decision, especially if you buy 'green' leccy.


Lastly, the RHI ASHP option would include DHW, so I was just combining a number of thoughts:
1. Money to buy thermo panels.
2. Need for DHW.
3. More efficient heating.

and I wondered if the costs would work out better that way. Just an ickle ponder.

Solarchaser

Ok, so you have just blown my *knowledge * out of the water.

I was certain ashp was essentially a radiator outside with a fan, some refrigerant a compressor and an ugly heater matrix (radiator) inside, and a fan to blow the heated or cooled air about.

I can do hot water too?

I'd love an ashp to act as air con in the 3 days of Scottish summer, but as the previously referred to trouble and strife opens windows, it would be no good as a heater.

The thing with batts is more my.... annoyance I guess, of exporting electric all day to the electric companies for *free* (I get fit for some of it), to then buy it again at night.
I get far more enjoyment/satisfaction/general warm feeling out of seeing the batts do their thing, than I should.
I cant financially justify more batts I'm pretty sure, or it would be up around 15 years.
I've purposely not done the calculations, as it might convince me not to.... and I WANT MORE!!! (Imagine petulant child stamping here).

I'm gonna have to go off and search ashp +hw now

Martyn1981

Solarchaser wrote: »

I'd love an ashp to act as air con in the 3 days of Scottish summer, but as the previously referred to trouble and strife opens windows, it would be no good as a heater.

Fun fact - (At least I hope it's a fact), whilst an ASHP or GSHP can also pump cold water around your radiators, if you do that, then you can't qualify for RHI, it has to be heat only. AAAAAAHHHHHHH!!!!!

Solarchaser

Ok so I now see what you mean about ashp for hw, however the little part of my house I could fit one that's obscured from view would be no good for airflow through it, and theres no way the wife would let it in the back garden.

Thanks though Mart, its given me more food for thought, and a better understanding of these things.

I have the energy saving trust coming out during the week to discuss options for making me greener, so I'll now have plenty to discuss with them, and with the reading over the last hour I'm pushing more to solar thermal, and maybe underfloor heating for at least part of the house

Reed_Richards

Solarchaser wrote: »

I can do hot water too?

Yes and no. Heating something using a heat pump uses electricity more efficiently that heating using just electric current as your immersion heater would. But a heat pump transfers heat from somewhere outside your house to inside your house and it is most efficient the smaller the temperature difference between the two. So heat pumps are frequently paired with underfloor heating because you don't need or want the temperature of the water circulating under your floor to be that high, not as high as the temperature of water circulating through radiators. Heating the water in a hot water tank to 55 C is much more of a challenge for a heat pump.

The system that the OP was posting about would seem to be an air source heat pump but using a large heat collector area rather than a fan blowing air over a smaller collector area. To describe something as "thermodynamic" is a meaningless way of obscuring the means by which it functions. Everything is thermodynamic; ye cannae get round the laws of physics.

Solarchaser

Indeed ye cannae, thanks

Reed_Richards

Solarchaser wrote: »

... the previously referred to trouble and strife opens windows...

Maybe a heat exchange fan is the answer? You get the fresh air but without so much loss of heat. By way of an example, https://www.envirovent.com/products/heat-recovery-ventilation-mvhr/heatsava/ although I have no idea whatsoever how well this performs.

zeupater

Reed_Richards wrote: »

... The system that the OP was posting about would seem to be an air source heat pump but using a large heat collector area rather than a fan blowing air over a smaller collector area ...

Hi

... or maybe even blowing air over a far larger heat exchange surface area formed by hundreds or thousands of fins/plates in a confined area ... more air mass per unit time over a larger surface area with better control of the temperature gradient as opposed to various forms of passive heat transfer isn't exactly something that the original designers of heat-pumps would have tended to overlook! ...

HTH
Z

Reed_Richards

zeupater wrote: »

... or maybe even blowing air over a far larger heat exchange surface area formed by hundreds or thousands of fins/plates in a confined area ...

I feel suitably chastised - yes of course the heat transfer area will be very large by design. I was struggling to see any possible merit in the system highlighted by the OP except that, possibly, it didn't involve a fan.

zeupater

Reed_Richards wrote: »

I feel suitably chastised - yes of course the heat transfer area will be very large by design. I was struggling to see any possible merit in the system highlighted by the OP except that, possibly, it didn't involve a fan.

Hi

We've seen plenty of claims regarding thermodynamic panels over the years, even claiming that nighttime energy efficiency resulted from black body radiation as opposed to simple convected heat exchange with air mass!

Effectively, when in sunlight, the black panel surface area does have the ability to 'collect' heat in a similar way to solar thermal & use this to increase solution efficiency, however, much of the time that heating is required it's actually dark or cloudy and even more importantly, the weather has a marginal dewpoint resulting in condensation, then frost, which is pretty reflective! ....

Many years ago I visited someone (not in UK) who had a really nice looking (and expensive!) thermodynamic 'sculpture' in their back garden, below which was a carpet of snow ... the snow was pretty much a permanent feature in the heating season no matter how green the rest of the garden looked .... mind though, the entire thing looked really great when sparkling brightly when reflecting sunlight, even though it was actually painted black!! ... next time I visited the 'sculpture' had disappeared and a more conventional heat exchange solution was in place ...

HTH
Z