Jump to content
House Price Crash Forum

Archived

This topic is now archived and is closed to further replies.

SarahBell

Sunamp pv hot water

Recommended Posts

Depends on how much it costs and what system you have, if you have combo system then may be worth it.

If you have cylinder system then dumping excess PV into cylinder via another heating element may be more cost effective overall. This works best if you have a larger cylinder designed for the job.

Another alternative would be a power wall type product (tesla) and dump excess PV into batteries. This could be used to charge electric car or feed back into supply during higher demand periods. But batteries are expensive so power wall expensive. There may be options later to re-use car batteries when they are below their useful capacity but still have plenty of life left as a power dump with decent amount of storage capacity and life left in them.

 

 

Share this post


Link to post
Share on other sites
3 minutes ago, onlyme2 said:

Depends on how much it costs and what system you have, if you have combo system then may be worth it.

If you have cylinder system then dumping excess PV into cylinder via another heating element may be more cost effective overall. This works best if you have a larger cylinder designed for the job.

Another alternative would be a power wall type product (tesla) and dump excess PV into batteries. This could be used to charge electric car or feed back into supply during higher demand periods. But batteries are expensive so power wall expensive. There may be options later to re-use car batteries when they are below their useful capacity but still have plenty of life left as a power dump with decent amount of storage capacity and life left in them.

 

 

The solar batteries are just being introduced.. not sure what stage this is at - but yes it's looking likely that in the next few years it'll be worth throwing a bit of solar up and capturing the energy for your own use. 

Share this post


Link to post
Share on other sites
13 minutes ago, onlyme2 said:

Depends on how much it costs and what system you have, if you have combo system then may be worth it.

If you have cylinder system then dumping excess PV into cylinder via another heating element may be more cost effective overall. This works best if you have a larger cylinder designed for the job.

Another alternative would be a power wall type product (tesla) and dump excess PV into batteries. This could be used to charge electric car or feed back into supply during higher demand periods. But batteries are expensive so power wall expensive. There may be options later to re-use car batteries when they are below their useful capacity but still have plenty of life left as a power dump with decent amount of storage capacity and life left in them.

 

 

Yeah, we have an immersun diverting the excess electricity from our PV installation into our immersion heater.  This could be more efficient - though perhaps not worth replacing the existing system for (ours was a £500 upgrade to the PV installation - I doubt this is that cheap). 

Edit: This place is selling them for £2.1K

https://theevohomeshop.co.uk/sunamp-heat-batteries/113-sunamp-pv-5-kwh-heat-batteries.html

 

 

Share this post


Link to post
Share on other sites

Cannot find price of system but there is a comparative table.

Price in comparison with lithium, 2x better with Sunamp c.f. cost of lithium battery solution.

Wh/l advatange 2x better with Sunamp c.f. power density of lithium battery.

With improvements in lithium and very likely large amount of competition coming in providing power wall type products, this could be a niche product with a very limited shelf life. Big advantage of PV->battery is that battery can be put nearly anywhere out of sight, having to be plumbed into water system reduces the locations that this system can be placed, many houses won't have the appropriate space. Bad example showing it stuck in a conservatory in the advertising vid.

If you want instant hot water pumping round the a large part of the pipework is not all that efficient. An instant heat tap int he kitchen would not have anywhere near the losses. 

Also with electric cars you also have the opportunity of using the car itself as a power dump - any excess goes to the car parked outside, if applicable of course and not parked at work during the day.

http://www.all-energy.co.uk/__novadocuments/86994?v=635676512389600000

 

Share this post


Link to post
Share on other sites
8 minutes ago, StainlessSteelCat said:

Yeah, we have an immersun diverting the excess electricity from our PV installation into our immersion heater.  This could be more efficient - though perhaps not worth replacing the existing system for (ours was a £500 upgrade to the PV installation - I doubt this is that cheap). 

Edit: This place is selling them for £2.1K

https://theevohomeshop.co.uk/sunamp-heat-batteries/113-sunamp-pv-5-kwh-heat-batteries.html

 

 

We don't have a hot water tank.

1.7k+  vat in their brochure.

Share this post


Link to post
Share on other sites
8 minutes ago, SarahBell said:

We don't have a hot water tank.

1.7k+  vat in their brochure.

Definitely worth considering then. Although by their own figures you're looking at around 7-8 years payback. Probably also depends on whether you are using the electricity you're producing during the day.

Finally, count on this only working well about 8 months of the year. After a summer of <£10/month energy bills and boiling hot water - the end of October hits us with a triple whammy of clocks going back, luke warm water from the tank due to reduced PV output/less spare capacity, and therefore increased energy bill. Still the feed-in tariff payments help a little.

Share this post


Link to post
Share on other sites
1 hour ago, StainlessSteelCat said:

Definitely worth considering then. Although by their own figures you're looking at around 7-8 years payback. Probably also depends on whether you are using the electricity you're producing during the day.

Finally, count on this only working well about 8 months of the year. After a summer of <£10/month energy bills and boiling hot water - the end of October hits us with a triple whammy of clocks going back, luke warm water from the tank due to reduced PV output/less spare capacity, and therefore increased energy bill. Still the feed-in tariff payments help a little.

 

We try to use as much as we can of what we generate... It'd be nice to use much more of it in a productive way.

Share this post


Link to post
Share on other sites

I don't have sound on this PC at the moment, but basically from the video it looks as if they're using a load of dirt cheap sodium acetate handwarmers to store the energy?

I guess if you have a combination boiler type system with no hot water tank then this isn't a bad idea; but I would have thought for a similar price you could probably get a hot water tank installed and use an immersun or similar? The thing appears to be the size of a water tank anyway.

The whole situation gets on my nerves, it would be far more efficient to just export the electricity to the grid (which is what the Feed-In Tariff is supposed to compensate you for) and use gas (or solar hot water panels) to heat the water; as usual a crap subsidy system creates perverse incentives. I don't blame anyone for minimising their own bills if they can legally do so, I would do the same, but as someone who doesn't have solar PV and can't install it because this house is in a conservation area, it winds me up that the government are paying people for electricity that they are using themselves! <_<

Share this post


Link to post
Share on other sites
3 minutes ago, Rave said:

I don't have sound on this PC at the moment, but basically from the video it looks as if they're using a load of dirt cheap sodium acetate handwarmers to store the energy?

I guess if you have a combination boiler type system with no hot water tank then this isn't a bad idea; but I would have thought for a similar price you could probably get a hot water tank installed and use an immersun or similar? The thing appears to be the size of a water tank anyway.

The whole situation gets on my nerves, it would be far more efficient to just export the electricity to the grid (which is what the Feed-In Tariff is supposed to compensate you for) and use gas (or solar hot water panels) to heat the water; as usual a crap subsidy system creates perverse incentives. I don't blame anyone for minimising their own bills if they can legally do so, I would do the same, but as someone who doesn't have solar PV and can't install it because this house is in a conservation area, it winds me up that the government are paying people for electricity that they are using themselves! <_<

I agree.   It is a selfish solution for 'excess power generation' which is actually just 'power generation which I can't currently use and I don't want to just give it away, even though it would be very useful for others in the UK and would reduce greenhouse gas emissions'

Anyway, it is an expensive solution to an artificial problem -- not really something to worry about.

[There does seem to be quite a bit of pipework etc in the box (along with a horrible mix of plastic and compression joints) - just what are they doing in there beyond just having a heat transfer loop, a thermostatic mixer and a few heating elements?]

Share this post


Link to post
Share on other sites
1 hour ago, Rave said:

I don't have sound on this PC at the moment, but basically from the video it looks as if they're using a load of dirt cheap sodium acetate handwarmers to store the energy?

I guess if you have a combination boiler type system with no hot water tank then this isn't a bad idea; but I would have thought for a similar price you could probably get a hot water tank installed and use an immersun or similar? The thing appears to be the size of a water tank anyway.

The whole situation gets on my nerves, it would be far more efficient to just export the electricity to the grid (which is what the Feed-In Tariff is supposed to compensate you for) and use gas (or solar hot water panels) to heat the water; as usual a crap subsidy system creates perverse incentives. I don't blame anyone for minimising their own bills if they can legally do so, I would do the same, but as someone who doesn't have solar PV and can't install it because this house is in a conservation area, it winds me up that the government are paying people for electricity that they are using themselves! <_<

Even as a beneficiary, I agree. I guess the only thing that mitigates it a little in my own circumstances is there is no mains gas in my area and so the water would be heated by electricity anyway. I did look into solar water heating but it wasn't feasible with my roof space. The immersun is quite smart at heating the tank to temperature -and then exporting any further excess to the grid.  Another perversity is that you were basically incentivised to put only 4kw on your roof. With our roof we could probably have fitted another 2kw, but you aren't incentivised to do so. 

Share this post


Link to post
Share on other sites
1 hour ago, StainlessSteelCat said:

Even as a beneficiary, I agree. I guess the only thing that mitigates it a little in my own circumstances is there is no mains gas in my area and so the water would be heated by electricity anyway. I did look into solar water heating but it wasn't feasible with my roof space. The immersun is quite smart at heating the tank to temperature -and then exporting any further excess to the grid.  Another perversity is that you were basically incentivised to put only 4kw on your roof. With our roof we could probably have fitted another 2kw, but you aren't incentivised to do so. 

No mitigation required, unless you were somehow involved with writing the rules of the scheme! ;)

Share this post


Link to post
Share on other sites
14 hours ago, onlyme2 said:

Cannot find price of system but there is a comparative table.

Price in comparison with lithium, 2x better with Sunamp c.f. cost of lithium battery solution.

Wh/l advatange 2x better with Sunamp c.f. power density of lithium battery.

With improvements in lithium and very likely large amount of competition coming in providing power wall type products, this could be a niche product with a very limited shelf life. Big advantage of PV->battery is that battery can be put nearly anywhere out of sight, having to be plumbed into water system reduces the locations that this system can be placed, many houses won't have the appropriate space. Bad example showing it stuck in a conservatory in the advertising vid.

If you want instant hot water pumping round the a large part of the pipework is not all that efficient. An instant heat tap int he kitchen would not have anywhere near the losses. 

Also with electric cars you also have the opportunity of using the car itself as a power dump - any excess goes to the car parked outside, if applicable of course and not parked at work during the day.

http://www.all-energy.co.uk/__novadocuments/86994?v=635676512389600000

 

 

Maybe a (much?) cheaper alternative if space is not an issue is a DIY heat battery involving a water or other fluid (automotive coolant?) tank sited close to the combi boiler. PV excess gets dumped into tank, and the cold water is fed through a heat exchanger to the combi inlet.

 

Guess this would also work with a solar tube setup too.

 

Could the cost of an inverter and the eleccy mains gubbins be avoided too if the PV was solely used for heating the tank?  panels + tank + elec heater element + fluid heat exchanger + plumbing costs in total.

Wondering about Legionella risk in the water volume sitting in the pipe work though, guess it is no worse than the sun amp setup. What happens if the hot water isn't used for a period of a few days, might you end up with a small volume of potentially nasty stuff which has been teed up in the heat exchanger but not used?

 

edit I'm guessing it is assumed the tank will be at a temperature high enough to kill the bacteria in the small volume sitting in the exchanger.

Share this post


Link to post
Share on other sites
1 hour ago, The Knimbies who say No said:

 

Maybe a (much?) cheaper alternative if space is not an issue is a DIY heat battery involving a water or other fluid (automotive coolant?) tank sited close to the combi boiler. PV excess gets dumped into tank, and the cold water is fed through a heat exchanger to the combi inlet.

 

Guess this would also work with a solar tube setup too.

Should be a bit cheaper.  A simple mains pressure unvented would be about £300.  

£300?  -- because it's only equivalent to 50 litres.  I like it in the vid where the guy says '50 litres!' like it is some kind of amazing amount of storage.  A 'normal' hot water tank would be more than 120 litres, a decent thermal storage system more like 250 litres

1 hour ago, The Knimbies who say No said:

Could the cost of an inverter and the eleccy mains gubbins be avoided too if the PV was solely used for heating the tank?  panels + tank + elec heater element + fluid heat exchanger + plumbing costs in total.

 

It would possibly be if you were doing it yourself, but the whole point of solar PV is the feed-in-tariff, so nearly everyone with solar PV will have all the inverter gubbins anyway.

You certainly wouldn't do this as the only load for a new PV system -- if you were only interested in the heat you'd put in a solar thermal system which would be smaller and cheaper for the same thermal gain.

1 hour ago, The Knimbies who say No said:

 

Wondering about Legionella risk in the water volume sitting in the pipe work though, guess it is no worse than the sun amp setup. What happens if the hot water isn't used for a period of a few days, might you end up with a small volume of potentially nasty stuff which has been teed up in the heat exchanger but not used?

 

edit I'm guessing it is assumed the tank will be at a temperature high enough to kill the bacteria in the small volume sitting in the exchanger.

It is the same situation with most other heating systems -- if you don't use them for a few days then the residual water is a tiny theoretical risk -- but the main Legionnaire's risk comes from hot water left permanently hanging around for really long periods of time -- like a hot water tank set at a low temperature, where it is constantly being topped up but with sufficient old water remaining to maintain (and feed) the bacterial colony.

Share this post


Link to post
Share on other sites
1 hour ago, The Knimbies who say No said:

 

Maybe a (much?) cheaper alternative if space is not an issue is a DIY heat battery involving a water or other fluid (automotive coolant?) tank sited close to the combi boiler. PV excess gets dumped into tank, and the cold water is fed through a heat exchanger to the combi inlet.

 

Guess this would also work with a solar tube setup too.

 

Could the cost of an inverter and the eleccy mains gubbins be avoided too if the PV was solely used for heating the tank?  panels + tank + elec heater element + fluid heat exchanger + plumbing costs in total.

Wondering about Legionella risk in the water volume sitting in the pipe work though, guess it is no worse than the sun amp setup. What happens if the hot water isn't used for a period of a few days, might you end up with a small volume of potentially nasty stuff which has been teed up in the heat exchanger but not used?

 

edit I'm guessing it is assumed the tank will be at a temperature high enough to kill the bacteria in the small volume sitting in the exchanger.

Yes you could go the "wet" route and just dump and store the covnerted heat. Depends on where yo are starting from with your existing system. Depeds where you are starting from, we've got an old tank fed system, new combi and storage tank is probably what we will go with and then add thermal solar first and look at other PV options.The FIT scheme really dominates the calculations for previous adopters in that regard.

A typical thermal solar systems might look this:

http://www.weatherenergy.co.uk/solar-thermal/how-it-works

The PV power dump would just be an additional immersion heating coil in such a system. Basically the gain is made by having pre-heated water feeding the boiler, so no real difference or risk their with water quality over any other system perfromaing a simialr task. As you point out the advantage is that multiple heating loops/routes can be used in such a system so thermal solar could easily be integrated as well.

Share this post


Link to post
Share on other sites

Thanks for the views above, dgul and OM2.

I'm redecorating a place prior to moving in, it has a basement with the combi on a wall, the other side of which faces SE and gets a lot of direct unobstructed sun- no trees or houses get in the way until approximately 4pm, I noticed today.

There is room right beside the combi for a decent sized tank, and the wall could easily be drilled to feed homebrew solar collector panels, which due to the garden layout would not be visible from the house or a particular obstruction in the garden if mounted at head height or below which they would be straight through from the combi. Seems too good to be true but that's the situation. Just crying out for a solar system. Either PV to an immersion element or a fluid circulating array. Guess I could run a solar pump to push fluid thought the collector(s) during the sunny times and if the working fluid is auto coolant it'll be good down to -30 deg. C or less so no worries about the pump powering down on cold nights.

 

Hmm, lots to think about. 

Share this post


Link to post
Share on other sites
49 minutes ago, The Knimbies who say No said:

Thanks for the views above, dgul and OM2.

I'm redecorating a place prior to moving in, it has a basement with the combi on a wall, the other side of which faces SE and gets a lot of direct unobstructed sun- no trees or houses get in the way until approximately 4pm, I noticed today.

There is room right beside the combi for a decent sized tank, and the wall could easily be drilled to feed homebrew solar collector panels, which due to the garden layout would not be visible from the house or a particular obstruction in the garden if mounted at head height or below which they would be straight through from the combi. Seems too good to be true but that's the situation. Just crying out for a solar system. Either PV to an immersion element or a fluid circulating array. Guess I could run a solar pump to push fluid thought the collector(s) during the sunny times and if the working fluid is auto coolant it'll be good down to -30 deg. C or less so no worries about the pump powering down on cold nights.

 

Hmm, lots to think about. 

Sounds like a good idea.  Don't bother with homebrew thermal -- get a decent evaculated tube setup, they're cheap enough.  You on mains pressure? -- if you've just got a header tank then hot water tanks are cheaper.  Technically you have to have building regs for unvented mains as well.  You could get a thermal store to get around this for £££s - but if you're into homebrew you can do it yourself using a plate heat exchanger and a cheap (maybe second hand) vented hot water tank -- you can salvage a PHE from an old combi-boiler or they're about £80 new.  If you've not looked hard try the forums at http://www.navitron.org.uk and places like http://greenbuildingforum.co.uk -- don't necessarily buy from there but at least get an idea of prices.  

Share this post


Link to post
Share on other sites
9 hours ago, dgul said:

Sounds like a good idea.  Don't bother with homebrew thermal -- get a decent evaculated tube setup, they're cheap enough.  You on mains pressure? -- if you've just got a header tank then hot water tanks are cheaper.  Technically you have to have building regs for unvented mains as well.  You could get a thermal store to get around this for £££s - but if you're into homebrew you can do it yourself using a plate heat exchanger and a cheap (maybe second hand) vented hot water tank -- you can salvage a PHE from an old combi-boiler or they're about £80 new.  If you've not looked hard try the forums at http://www.navitron.org.uk and places like http://greenbuildingforum.co.uk -- don't necessarily buy from there but at least get an idea of prices.  

 

Thanks again, reckon a vented system may be the way to go. As it happens I have a plate heat exchanger kicking around as part of my (as yet unconstructed, possibly never will be ) home brewery, so even if I don't use that one I can have a play and see how it would work. Biggest issue is correctly sizing the tank and collectors so that it achieves a usefully high temp with a big volume but not so high that it might eg boil the incoming feed at times of greatest influx. Also I'm wondering if the size of the array could be varied with the seasons to allow greater collecting area in winter months. In practical terms I guess that would mean covering up parts of an oversized array in summer. Which seems daft. Am also wondering if it might be possible to get it hot enough I winter to make any useful contribution to the central heating, by running the returning fluid through the tank. The danger is that it starts working in reverse! 

 

I'll this discussion onto anoth thread, apologies for cluttering but thanks for the original post which has got me thinking. Guess I'll resurrect Kurt Barlow's solar build thread or start a new one. Thanks.

Share this post


Link to post
Share on other sites
1 hour ago, The Knimbies who say No said:

 

Thanks again, reckon a vented system may be the way to go. As it happens I have a plate heat exchanger kicking around as part of my (as yet unconstructed, possibly never will be ) home brewery, so even if I don't use that one I can have a play and see how it would work. Biggest issue is correctly sizing the tank and collectors so that it achieves a usefully high temp with a big volume but not so high that it might eg boil the incoming feed at times of greatest influx. Also I'm wondering if the size of the array could be varied with the seasons to allow greater collecting area in winter months. In practical terms I guess that would mean covering up parts of an oversized array in summer. Which seems daft. Am also wondering if it might be possible to get it hot enough I winter to make any useful contribution to the central heating, by running the returning fluid through the tank. The danger is that it starts working in reverse! 

 

I'll this discussion onto anoth thread, apologies for cluttering but thanks for the original post which has got me thinking. Guess I'll resurrect Kurt Barlow's solar build thread or start a new one. Thanks.

The controller should do most of the necessary flow control for you to maintain appropriate temperatures. If looking for DIY route then make it easier on yourself, A reasonable amount of second hand installs floating around on Ebay, just buy the appropriate components for a setup.

When you can buy £2.5K of tubes, controller etc for £250, it is very cost effective! Just then need to find a tank.

http://www.ebay.co.uk/itm/solar-thermal-hot-water-system-/201650568143?hash=item2ef34f7bcf:g:VLEAAOSw65FXuD-2

 

Share this post


Link to post
Share on other sites
28 minutes ago, onlyme2 said:

The controller should do most of the necessary flow control for you to maintain appropriate temperatures. If looking for DIY route then make it easier on yourself, A reasonable amount of second hand installs floating around on Ebay, just buy the appropriate components for a setup.

When you can buy £2.5K of tubes, controller etc for £250, it is very cost effective! Just then need to find a tank.

http://www.ebay.co.uk/itm/solar-thermal-hot-water-system-/201650568143?hash=item2ef34f7bcf:g:VLEAAOSw65FXuD-2

 

Cheers, pretty impressive for the money, maybe more reasonable compared to the actual savings achievable. I won't be doing it for a while but it's good to have a think. Back to sanding doors....

Share this post


Link to post
Share on other sites

  • Recently Browsing   0 members

    No registered users viewing this page.

  • Next General Election   94 members have voted

    1. 1. When do you predict the next general election will be held?


      • 2019
      • 2020
      • 2021
      • 2022

    Please sign in or register to vote in this poll. View topic


×

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.