Solar assisted heat pumps - night time solar

LaurenAlderson

I have a keen interest in all the new renewable systems that are coming into play at the moment and am totally fascinated by solar assisted heat pumps. They now seem to be replacing traditional solar thermal. The thing i just can't believe is that these systems actually generate hot water at night or in bad weather or freezing conditions. The term 'solar' in the case of these systems doesn't just apply to the sun. Does anyone have some experience of solar hot water generators?

pile-o-stone

I think these are also referred to as Thermodynamic panels. They work by circulating a very cold liquid refrigerant through veins in the panel. This liquid is approximately -22°C when it enters the panel. Due to the large temperature difference between the liquid in the panel and the outside air a heat transfer will take place. Heat energy is absorbed by the panel and transferred into a store of water within the property. Thermodynamic panel systems are designed to heat hot water and constantly keep the water hot 24 hours a day at 55°C. The panels will work at night, as they work on a similar principle to a fridge, and can be positioned facing any direction. They work quicker in direct sunlight (hence the solar assistance) because there is a higher temperature difference, so the heat can be harvested quicker, but the result is the same and the temperature will not go above 55°C, no matter how hot the sunny day gets.

It works on a similar principle as other heat pump technologies (air sourced, water sourced & ground sourced). I'd imagine in the UK that it would be more efficient than air and water heat pumps but not ground sourced heat pumps, because it would have consistently higher source temperature to extract heat from.

zeupater

LaurenAlderson wrote: »

I have a keen interest in all the new renewable systems that are coming into play at the moment and am totally fascinated by solar assisted heat pumps. They now seem to be replacing traditional solar thermal. The thing i just can't believe is that these systems actually generate hot water at night or in bad weather or freezing conditions. The term 'solar' in the case of these systems doesn't just apply to the sun. Does anyone have some experience of solar hot water generators?

Hi

No experience, but there was a detailed discussion on this forum about 5 years ago which may be of some interest .... http://forums.moneysavingexpert.com /showthread.php?t=4205509&page=2 ... read the thread from the beginning, but I've linked to page 2 because that's where the technical discussion starts! ...

We're pretty much into energy efficiency, but still have the same views as expressed then ...

After that, if you're still interested in heating hot water with solar, there's some reasonable unbiased background/seasonal information on both 'standard' PV & thermal options on a blog-site here ... https://goo.gl/m95Cwz

HTH
Z

LaurenAlderson

It works on a similar principle as other heat pump technologies (air sourced, water sourced & ground sourced). I'd imagine in the UK that it would be more efficient than air and water heat pumps but not ground sourced heat pumps, because it would have consistently higher source temperature to extract heat from.

Thanks for all the advice.
I did a little bit more digging on ground source heat pumps, correct me if i'm wrong but aren't they quite expensive to install, and require a lot of ground work, digging holes etc?. Yes they are more consistent than air source, but as the temperature gets colder their COP must be altered too?

The thing i find so fascinating about solar assisted, is that they work with the air temperature/weather and use it to their advantage.
I found an interesting article by a company on Facebook, although i'm not allowed to post links yet. Infinity Innovations Ltd have published an article called "Bunsen -inside my innovation".This is just one company, to my knowledge there are quite a few distributing similar products? I wonder if this is going to mean solar thermal will become obsolete?

zeupater

LaurenAlderson wrote: »

Thanks for all the advice.
I did a little bit more digging on ground source heat pumps, correct me if i'm wrong but aren't they quite expensive to install, and require a lot of ground work, digging holes etc?. Yes they are more consistent than air source, but as the temperature gets colder their COP must be altered too?

The thing i find so fascinating about solar assisted, is that they work with the air temperature/weather and use it to their advantage.
I found an interesting article by a company on Facebook, although i'm not allowed to post links yet. Infinity Innovations Ltd have published an article called "Bunsen -inside my innovation".This is just one company, to my knowledge there are quite a few distributing similar products? I wonder if this is going to mean solar thermal will become obsolete?

Hi

What are you looking to heat - DHW or the property? ... If you can provide some info/ rough details then someone may be able to provide some input using related renewable energy/high efficiency technology combinations ...

Did you read the discussion thread linked ? - if so, nothing's really changed much, apart from the number of suppliers making outrageous performance claims ...

HTH
Z

LaurenAlderson

It's actually my parents looking for a DHW system for their new property which is under renovation. I'm looking into some systems for them although I only have very limited technical knowledge. They currently run on oil which has been proving very expensive.
Outrageous claims? Can you give any examples?

zeupater

LaurenAlderson wrote: »

It's actually my parents looking for a DHW system for their new property which is under renovation. I'm looking into some systems for them although I only have very limited technical knowledge. They currently run on oil which has been proving very expensive.
Outrageous claims? Can you give any examples?

Hi

I think you really do need to make a mug of coffee, sit down and sift through the links in post#3 in order to understand the issues involved, it'll take a little time, but you are talking about £thousands so it could just work out to be quite a money-saving exercise ... afterwards, come back and ask questions on anything that the previous discussion doesn't cover, or you don't follow !

HTH
Z

Solarchaser

Holy thread revival batman....

So I got an email about bunsen air.
Thermodynamic panels. And done a bit of searching and ended up here.

I spent a couple of hours reading the thread you linked Z, so I understand you have some reservations about the cop stated (understatement).

I know you have solar thermal, and you have given me previously some links about thermal.

So I'm thinking solar thermal, or maybe thermodynamic... or maybe just immersion from my PV, but I have a bit of roof space left, and have enough PV (can you ever have enough?)

The biggest issue with thermodynamic seemed to be the price vs return... and ludicrous claims.

So my question for you is, what if they were the same price?

Seems to be around the 4k mark for either system just now (havent delved into the nitty gritty cos tbh I'm not 100% sold on spending more money for a 10 year + roi)

The bunsen kit is on the think renewables website, I cant link, but I'm sure you can find it... or probably already know about it.

No specific info about cop, a 444w rotary rather than piston pump.
Various efficiency claims, some contradictory.
Has a weekly legionela cycle, which I thought strange on a sealed tank, but says it can be done from the thermal..... or immersion.
Says it's good all year round, but uses gas boiler as a backup.... why if it can do all year?

The appeal is the 55c which is directly useable, whereas the 35c from thermal isn't hot enough to be directly useable for showers.
But is it a real 55c is the question??

I have quite a bit of export just now. So I could just immersion from PV, though I do like the idea of exporting to grid on time of use tariffs.
And I suppose if I did that, I could just use immersion on the e7 etc....

Lots of balls in the air.

Martyn1981

Sorry to butt in, but I'm interested in the idea possibly for a sister project ..... actually my sister's project.

I'm having trouble getting the numbers to make sense, if you already have PV, since it seems like a lot of expenditure v's leccy. And if the leccy is priced at a mix of E7 and 'free' PV (actually it should be priced at export rate of around 5.5p), then is there a better alternative for the investment monies.

To be clear, I'm not saying pocket the cash, and I'm 100% behind the idea, or satisfaction of being more self sustainable, but could you do better with a small green fund investment and buying some import?

I'm not suggesting a right or wrong, just thinking out loud. Also, how much is all the kit, as if you are entering into the realms of multiple £1,000's, then you might also be getting closer to an ASHP heating system for the house (with DHW) and the RHI payments for 7yrs.

Again just pondering, and whilst I like setting my electrons free to roam around my neighbours houses 'greening' them, PV + batt + immersion seems like a good option, especially as we move forward into periods of excess RE .... eventually!

If this seems like a ramble, that's coz it is, just thinking out loud, sorry.

Reed_Richards

LaurenAlderson wrote: »

Thanks for all the advice.
I did a little bit more digging on ground source heat pumps, correct me if i'm wrong but aren't they quite expensive to install, and require a lot of ground work, digging holes etc?

My research would agree. You either need a borehole which is expensive to dig or an area of lawn (i.e. ground that will not be dug into) larger than most properties posses.

LaurenAlderson wrote: »

I wonder if this is going to mean solar thermal will become obsolete?

The favoured solution these days is to use solar PVs to heat water via an immersion heater; solar thermal hot water panels are already semi-obsolete.

Solarchaser

Lol @ butting in, it was me butting in to a 18 month old thread.

I'm not on e7 yet, but I plan to be in that sort of deal soon, (overnight ev charge and immersion in winter) with maybe an export tariff, though I'm not sure what you will *earn* will be worth the hassle factor if I'm honest.

Ashp is no good for me as the wife LOVES fresh air, so even if its peeing down, the windows will still be open.

I was thinking thermal partially because of rhi.

But yeah I have 6kwh of batts, which have made me even more obsessive with the PV.

Like just now, batts were full by 10am, and it's all pushing to grid now (well some as white goods are on) and so immersion would be good to sup it up and stop me buying hot water gas later, and shower leccy later, but.... if I increase my batteries I'll probably sup up the shoulder month excess with those, and so the immersion would need some help... so solar thermal or thermodynamic.

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