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New Build - deciding what renewables to use.

  • 31-10-2015 10:55pm
    #1
    Registered Users Posts: 6,565 ✭✭✭ funkey_monkey


    Hi

    We are in the process of speccing our new build and looking at what renewables to use.

    We are building a timber frame house which will be built to a high level of insulation to reduce engery costs.

    Presently we are looking at how to generate energy on site. It will be a 1700sqft single storey dwelling

    I am intending to use either pv panels or water heating panels on the garage roof - I don't want to install these on the house. A friend told me that in a windy area it might not be a good idea - hence why I though of the garage roof - rather than stressing the roof of my house. Are there any links to stress testing of these panels on the house roof?

    Would it still be difficult to have water heating panels on a detached garage roof and then pipe the heated water over to the house? I assume that the installation and insulation of this would be unfeasible? For this reason, I am leaning towards PV panels being my best option, correct?

    We had initially thought also about a ground pump, but with the house being highly insulated I thought that there would be minimal gain from the investment - considering that there would be reduced energy input required to heat the property and that the money could either be saved to reduce overall cost or redirected to PV panels. Is this logic correct?

    My understanding from speaking to some people with ground pumps is that you need a sizeable amount of land to make it work and then you still need a sizable amount of energy input to pump that water and extract the heat.

    So, purely on my little amount of research I've ruled out Ground Pumps (insufficient energy demand to make it worthwhile) and Water heating panels (due to desire to locate the panels on garage). Is this flawed thinking?

    The plan would be to install an oil burner for central heating. Is there any reason why we would not want to go down this route?
    In regards to PV panels, I know very little about them. How do I calculate the efficiency of them my my location - does location (inc hours of daylight, etc) greatly affect the calculations? I've been told by someone that their limited lifetime is around 10 years.

    They seem to be getting more popular so I assume that they are the way to go?

    Final query, an open fire is always nice on a winters night, but I don't fancy a log burner. Could we install a gas fire and use excess PV energy generated to offset this? How would it be calculated?

    Apologies for so many questions in advance - I don't want to go out to a supplier of these items without being fore warned about them.

    Like I said at the top, we are just begining and the above is just initial thoughts based on limited research so far.


    Any advice appreciated.

    Thanks.


«1

Comments

  • Registered Users Posts: 376 ✭✭ delfagio


    Just one thing to look at before proceeding with PV panels, they say that PV panels if they are a long way from the house that there are significant loses of power in long runs of cable, not sure if this is from the DC cable before going into the converter or from the AC cable between the converter and the fuse board. Just something to consider. Maybe the option of putting the PV panels on the house roof to reduce the cable runs.


  • Registered Users Posts: 6,565 ✭✭✭ funkey_monkey


    Would that not only be the case for direct feed to your own property? There is a supply line running beside our site.

    I thought I could sell the electricity in totality to the supplier and then buy back a more consistent supply using one of their green electricity tariffs?


  • Registered Users Posts: 1,627 ✭✭✭ quentingargan


    Your losses with electricity coming from a shed would be negligible compared to trying to run solar thermal, as I have seen done in the past. Solar PV is probably the most cost effective way to meet the renewables obligations in part L.

    However, at present you can't sell surplus electricity to the utility companies. You have to give them your surplus free or charge, or else put it in batteries. I expect by the time you have finished the house, that situation may well have changed. There was a tariff until end of last year, and its scrappage is hopefully not permanent.

    There are various calculators that work out the output of a panel. Another post on this forum recently gave the calculations. PM me if you need help on that.


  • Registered Users Posts: 6,565 ✭✭✭ funkey_monkey


    I'm in Northern Ireland - does inability to sell to the companies exist here too?


  • Registered Users Posts: 1,627 ✭✭✭ quentingargan


    I'm in Northern Ireland - does inability to sell to the companies exist here too?
    Ah - that's different. UK feed in tariffs are due to fall like a stone in January.

    In NI, you work on a combination of ROCs and export tariff. The prices were up for review in October AFAIK, but they were quite generous.


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  • Registered Users Posts: 6,565 ✭✭✭ funkey_monkey


    So, cut to the chase, is there any point in the renewables given the initial investment cost?
    Thinking of insulating the life out of the place and going for oil heating and scrapping the panel idea if there is little payback with them.

    I think I need to get the architect to give some advice or point us to someone without a vested interest in selling the product.


  • Registered Users Posts: 1,627 ✭✭✭ quentingargan


    Thinking of insulating the life out of the place and going for oil heating and scrapping the panel idea if there is little payback with them.

    Insulation is almost always the low hanging fruit and worth spending money on -especially during construction, when passive standards can be achieved that would not be achievable later by retrofit. If you do this and find that your house only requires a tiny amount of heating per year, then the payback time on expensive heating systems moves into decades rather than years.

    Working out the payback for solar PV would require you to know what the feed in tariff will be when you commission the system. Also, it will depend on the extent of your self-consumption. For example, if you opt for heat recovery ventilation, and work from home, you will use more of your PV produced electricity than a household with everyone out all day and surfing at the weekend. The bigger your PV array is, the lower the percentage of self-consumption achieved.


  • Registered Users Posts: 376 ✭✭ delfagio


    Then there is the other side of the coin with new builds, that it is nearly impossible or very hard to achieve meeting the Part L renewables requirements with just oil boiler, stove, geothermal or air source heat pumps etc without installing either Solar Panels for hot water or PV solar Panels.

    It is easier to meet Part L renewables requirement with PV Panels though, so although payback time for PV panels might be running toward decades, it might just be worth the investment

    Maybe don't rule them out just yet. Run the figures with your BER Assessor and see what would be required.

    For example oil boiler is cheap to install than the likes of geothermal or air source heat pumps etc, and with new builds been more insulated and airtight these days the oil running costs are low as there isn't a large heat demand from the houses these days as the retain a lot of heat and temperatures drop slowly. So maybe 300-400euro a year to heat house with oil.

    Say installing oil boiler might be 2000-3000euro including oil tank, fill of oil and commissioning where as geothermal or Air source could cost 10000-25000 and alone would still more than likely still not meet Part L.

    So then using oil boiler say 2000-3000euro, a wood burning stove say 2000euro, HRV approx 6000euro and say 1Kw PV Panel Array for say 4000euro might be the cheapest route to go in order to meet the Part L renewables requirements.

    Have a good think about it.


  • Registered Users Posts: 211 ✭✭ Wegian


    delfagio wrote: »


    Say installing oil boiler might be 2000-3000euro including oil tank, fill of oil and commissioning where as geothermal or Air source could cost 10000-25000 and alone would still more than likely still not meet Part L.

    So then using oil boiler say 2000-3000euro, a wood burning stove say 2000euro, HRV approx 6000euro and say 1Kw PV Panel Array for say 4000euro might be the cheapest route to go in order to meet the Part L renewables requirements.

    Have a good think about it.

    I would be interested in knowing whether you are speculating here or you have modeled this scenario?

    I ask as I am in the same situation as the OP and would be very interested in this.


  • Registered Users Posts: 376 ✭✭ delfagio


    Wegian wrote:
    I would be interested in knowing whether you are speculating here or you have modeled this scenario?

    Wegian wrote:
    I ask as I am in the same situation as the OP and would be very interested in this.


    To be honest I am more speculating here, as I am just in the finishing stages of our own self build, so haven't actually got the proof of running costs etc at the moment.

    But I have spoken to a lot of people regarding this and the opinion is that the outlay costs for geothermal and air source are too dear at anywhere between 10000-25000 as mentioned oil boiler could be 2000-3000.

    With PV panels it is easier to achieve the renewable energy requirements. Yes there's a big outlay costs and long payback period but in my opinion people are looking at their homes these days in "payback terms" instead of looking at them as well insulated, energy efficient, airtight comfortable houses to live in.


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  • Registered Users Posts: 1,627 ✭✭✭ quentingargan


    delfagio wrote: »
    With PV panels it is easier to achieve the renewable energy requirements. Yes there's a big outlay costs and long payback period but in my opinion people are looking at their homes these days in "payback terms" instead of looking at them as well insulated, energy efficient, airtight comfortable houses to live in.

    I think your price of €4K for a 1kw system is a bit steep. If it is done during the build process (fitted by the roofer and wired by the spark as part of their briefs) the cost should be about half that. Like you, I wouldn't justify it on the basis of payback, unless there is a generous FIT, but it is a low cost and maintenance free way of meeting Part L in the south, and it will wash its face over time.


  • Registered Users Posts: 12,526 ✭✭✭✭ galwaytt


    So, cut to the chase, is there any point in the renewables given the initial investment cost?
    Thinking of insulating the life out of the place and going for oil heating and scrapping the panel idea if there is little payback with them.

    I think I need to get the architect to give some advice or point us to someone without a vested interest in selling the product.


    The problem with that - and I'm going to assume you will be aiming for very good airtightness at the same time - is that the more efficient the fabric, the lower the heat load and. ...The worse your renewable situation. Its perverse, but the whole Part L in that respect is seriously wrong.

    To wit, we've built a house in recent times where the client was adamant that no panels be fitted, and the u-value was lowered, airtightness loosened and psi values increased just to satisfy a (frankly) nonsense regulation. So we built a 'lower' spec house purely because of it.

    Madness

    Ode To The Motorist

    “And my existence, while grotesque and incomprehensible to you, generates funds to the exchequer. You don't want to acknowledge that as truth because, deep down in places you don't talk about at the Green Party, you want me on that road, you need me on that road. We use words like freedom, enjoyment, sport and community. We use these words as the backbone of a life spent instilling those values in our families and loved ones. You use them as a punch line. I have neither the time nor the inclination to explain myself to a man who rises and sleeps under the tax revenue and the very freedom to spend it that I provide, and then questions the manner in which I provide it. I would rather you just said "thank you" and went on your way. Otherwise I suggest you pick up a bus pass and get the ********* ********* off the road” 



  • Registered Users Posts: 211 ✭✭ Wegian


    Question, which may be nutty, but nonetheless..

    If installing HRV and an internal heat source, a stove of some kind, and the HRV acts to distribute the heat throughout the house, albeit with 90% efficiency - does this remove the requirement for UFH or Radiators to distribute the heat?

    Apologies in advance if this is a hair brained idea.


  • Registered Users Posts: 1,627 ✭✭✭ quentingargan


    Wegian wrote: »
    Question, which may be nutty, but nonetheless..

    If installing HRV and an internal heat source, a stove of some kind, and the HRV acts to distribute the heat throughout the house, albeit with 90% efficiency - does this remove the requirement for UFH or Radiators to distribute the heat?

    Apologies in advance if this is a hair brained idea.

    I don't know the theory, but even with radiators in all rooms, my HRV doesn't maintain stable temperatures throughout the house, and you wouldn't want it to - you usually want your living area a bit warmer than the bedrooms.


  • Registered Users Posts: 211 ✭✭ Wegian


    I don't know the theory, but even with radiators in all rooms, my HRV doesn't maintain stable temperatures throughout the house, and you wouldn't want it to - you usually want your living area a bit warmer than the bedrooms.

    Good point. You would imagine that a stove in the living aread would radiate enough heat to ensure this is the warmest area.


  • Registered Users Posts: 2,544 ✭✭✭ MicktheMan


    Wegian wrote: »
    Question, which may be nutty, but nonetheless..

    If installing HRV and an internal heat source, a stove of some kind, and the HRV acts to distribute the heat throughout the house, albeit with 90% efficiency - does this remove the requirement for UFH or Radiators to distribute the heat?

    Apologies in advance if this is a hair brained idea.

    In general, no. The heat capacity of air is too low.


  • Registered Users Posts: 21,394 ✭✭✭✭ Mad_Lad


    The ESB are supposed to re-introduce the Feed In Tariff next year, I can't confirm but I would also be more inclined to go with Solar PV, Solar hot water, I don't see the benefit of solar hot water because your central heating covers this most of the year and solar PV can do much more "including" heating water.

    Solar calculators calculate that I would need 8 KwP for my yearly needs including charging the Leaf for about 20,000 Kms per year including the house. However previously the max to the grid was 5 kw on single phase, this is ridiculous. Hopefully this will change.

    The idea is I sell to the grid during the day, the ESB is my limitless "free" battery and buy back at night rate. Then I benefit while working shift that I can charge from the Solar during the day when working nights. But this 5 Kw limit to the grid is really poor.

    If we only had 3 phase to homes in Ireland !


  • Registered Users Posts: 211 ✭✭ Wegian


    Mad_Lad wrote: »
    The ESB are supposed to re-introduce the Feed In Tariff next year,

    Without this I don't see the benefit of the PV - generating electricity during the say when there is nobody there and not generating in the evening when electricity is required. Unless I am missing something....


  • Registered Users Posts: 21,394 ✭✭✭✭ Mad_Lad


    Wegian wrote: »
    Without this I don't see the benefit of the PV - generating electricity during the say when there is nobody there and not generating in the evening when electricity is required. Unless I am missing something....

    There's probably far less benefit of a hot water solar setup, you can use the electricity during the day, and can heat the hot water also. possibly get a battery to store the energy, a few electric heaters etc reduce heating costs, you can do far more with electricity.

    Admittedly, grid tie is best, or battery if the Tesla powerwall is as cheap as it's sounding.

    For those who have to have a renewable setup as part of building regs then Absolutely would go with solar PV.


  • Registered Users Posts: 671 ✭✭✭ mrsWhippy


    Mad_Lad wrote: »
    There's probably far less benefit of a hot water solar setup, you can use the electricity during the day, and can heat the hot water also. possibly get a battery to store the energy, a few electric heaters etc reduce heating costs, you can do far more with electricity.

    Admittedly, grid tie is best, or battery if the Tesla powerwall is as cheap as it's sounding.

    For those who have to have a renewable setup as part of building regs then Absolutely would go with solar PV.

    We're trying to make that decision at the moment for a 154 sq.m new build. There doesn't seem to be a huge cost difference between our two 'schemes' which would both meet Part L.

    Scheme 1 is Gas boiler + 30 Solar tubes + 0.5 kWp PV.
    Scheme 2 is 6kw A2W heat pump.

    The idea of a gas standing charge is deterring us from option 1. But also relying on the heat pump to heat hot water where as we could technically have it for 'free' is another consideration. We were also wondering if it would make sense to upgrade scheme 2 with some tubes for hot water too ... though these are costing more than I expected.

    Both schemes will have MVHR, UFH and a wood stove in common....and aiming for decent u-values and airtightness (<3)

    We're completely torn. Any advice?


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  • Registered Users Posts: 229 ✭✭ Bricriu


    If you're serious about a low-energy house, Google Passive Houses. Hundreds of these houses have been built in Ireland and I haven't heard anything but good reviews about them. Insulation is paramount in these houses. What's the use in generating heat if it is escaping through the roof, walls, and floor.

    I had one built and I'm extremely happy with its performance. It's a bit more expensive to build, but that extra cost is saved in running costs in the long run.

    It's a super comfortable house and I don't need a Central Heating system, just a wood-burner for cold weather. Fresh air is drawn in through a Ventilation System which heats the air a little using power from the motor. It also has Underfloor Heating which I rarely use.

    I live on the Connemara coast, with wild gales, and have had no problem with Solar Panels on the roof of the house.


  • Registered Users Posts: 671 ✭✭✭ mrsWhippy


    Bricriu wrote: »
    If you're serious about a low-energy house, Google Passive Houses. Hundreds of these houses have been built in Ireland and I haven't heard anything but good reviews about them. Insulation is paramount in these houses. What's the use in generating heat if it is escaping through the roof, walls, and floor.

    I had one built and I'm extremely happy with its performance. It's a bit more expensive to build, but that extra cost is saved in running costs in the long run.

    It's a super comfortable house and I don't need a Central Heating system, just a wood-burner for cold weather. Fresh air is drawn in through a Ventilation System which heats the air a little using power from the motor. It also has Underfloor Heating which I rarely use.

    I live on the Connemara coast, with wild gales, and have had no problem with Solar Panels on the roof of the house.

    Thanks. I'm already aware of what a passive house is, but tbh I'm not really interested in building a certified passive house. Anyway we've probably missed the boat on that as the plans have been granted permission and I know we'd probably have to make design changes for windows etc for additional solar gain, and other detailing if we were going down that road.

    I'm sure there is a sweet spot w.r.t build cost and energy efficiency, but i just haven't found out where that lies just yet!

    My goal at the moment is to come up with a build fabric that gives us the best airtightness and u-values possible to reduce our energy demands as much as possible, without increasing the build costs exponentially. I know we can focus on detailing around cold bridges etc which will give us a more comfortable home for little investment too.


  • Registered Users Posts: 1,627 ✭✭✭ quentingargan


    mrsWhippy wrote: »
    We're trying to make that decision at the moment for a 154 sq.m new build. There doesn't seem to be a huge cost difference between our two 'schemes' which would both meet Part L.

    Scheme 1 is Gas boiler + 30 Solar tubes + 0.5 kWp PV.
    Scheme 2 is 6kw A2W heat pump.

    Just surprised that Scheme 1 is with two types of solar. It would be cheaper by far to scrap the tubes and make up for that by increasing the PV. There is a fixed cost to installing PV of any size, but increasing it will cost you about €1 per watt, so adding 1500 watts to the 500 watts proposed would cost an extra €1500 roughly.

    Thats way cheaper than 30 tubes and all the plumbing involved. And if you have a 2kw system, you can later fit a diversion device to get your hot water from the PV anyhow.


  • Registered Users Posts: 671 ✭✭✭ mrsWhippy


    Just surprised that Scheme 1 is with two types of solar. It would be cheaper by far to scrap the tubes and make up for that by increasing the PV. There is a fixed cost to installing PV of any size, but increasing it will cost you about €1 per watt, so adding 1500 watts to the 500 watts proposed would cost an extra €1500 roughly.

    Thats way cheaper than 30 tubes and all the plumbing involved. And if you have a 2kw system, you can later fit a diversion device to get your hot water from the PV anyhow.

    That's very useful to know, thanks.

    We had originally specified no PV at all so I'm wondering why it was included in the report. Would it make more sense to have all PV here rather than all solar tubes then? I had thought about scrapping the PV altogether and upping the tubes, but I guess a family of 4 will only have a certain hot water demand so that might not make sense.


  • Registered Users Posts: 1,627 ✭✭✭ quentingargan


    mrsWhippy wrote: »
    That's very useful to know, thanks.

    We had originally specified no PV at all so I'm wondering why it was included in the report. Would it make more sense to have all PV here rather than all solar tubes then?
    The only real way to know is to look at the XML file from the BER assessor. If you can get that, you can play with options. Usually PV can replace solar and tick all the boxes for EPC, CPC and the Renewable Energy contribution


  • Registered Users Posts: 671 ✭✭✭ mrsWhippy


    The only real way to know is to look at the XML file from the BER assessor. If you can get that, you can play with options. Usually PV can replace solar and tick all the boxes for EPC, CPC and the Renewable Energy contribution

    Yeah, I have the two XMLs alright, have already tinkered around with them but haven't tried the above. Will give that a shot and see what happens, cheers!


  • Registered Users Posts: 21,394 ✭✭✭✭ Mad_Lad


    mrsWhippy wrote: »
    We're trying to make that decision at the moment for a 154 sq.m new build. There doesn't seem to be a huge cost difference between our two 'schemes' which would both meet Part L.

    Scheme 1 is Gas boiler + 30 Solar tubes + 0.5 kWp PV.
    Scheme 2 is 6kw A2W heat pump.

    The idea of a gas standing charge is deterring us from option 1. But also relying on the heat pump to heat hot water where as we could technically have it for 'free' is another consideration. We were also wondering if it would make sense to upgrade scheme 2 with some tubes for hot water too ... though these are costing more than I expected.

    Both schemes will have MVHR, UFH and a wood stove in common....and aiming for decent u-values and airtightness (<3)

    We're completely torn. Any advice?

    Passive is absolutely a great idea but since that is out I would recommend Solar PV along with heat pump, however I am not up to speed on heat pumps only that the pumps themselves are vastly better than just 5 years ago.

    I have one in the car (Nissan Leaf) to save energy and it's brilliant !

    However getting a good installer is essential. There are air to water pumps now too that can heat water like a normal boiler but they're not yet as efficient but they're as good as the ground pumps of just a few years ago, again I don't know much about them.


    The solar can help drive the heat pump.

    Get as much solar PV as you can and I'd forget the hot water panels because what do you want 300 litres of hot water for doing nothing ? The solar PV can heat the water and run all your appliances, cooking and it can also heat the water.

    I think the ESB are to re-introduce a feed in tariff sometime this year so you could export your excess and buy it back when you need it.

    Solar PV is vastly more useful than hot water panels that just heat water for fun.

    It's only a shame the max allowed to the grid on single phase is about 5.5 Kw. But it will still make a difference. You can also charge an EV and drive for half nothing, but that works best with a feed in tariff, solar sent to the grid for which you get paid when you're at work and you buy it back at night. Hopefully a feed in tariff will come this year.

    As much solar PV as you can afford and plenty of insulation.

    Spray foam isn't as popular in Ireland but it sure looks vastly better to any normal installation.


  • Registered Users Posts: 671 ✭✭✭ mrsWhippy


    Mad_lad, that's really interesting.

    Do you think it's financially worthwhile investing in PV even though it's not technically required to meet Part L (assuming we go with the A2W option)?

    Can you, or anyone else recommend an installer for Heat Pumps in the Dublin area? I've already gotten a few quotes from renewable companies, but would be interested to hear some first hand recommendations.

    We're also considering a SIP or ICF build potentially, so that will at least guarantee a well insulated building.

    Cheers!


  • Registered Users Posts: 21,394 ✭✭✭✭ Mad_Lad


    mrsWhippy wrote: »
    Mad_lad, that's really interesting.

    Do you think it's financially worthwhile investing in PV even though it's not technically required to meet Part L (assuming we go with the A2W option)?

    Can you, or anyone else recommend an installer for Heat Pumps in the Dublin area? I've already gotten a few quotes from renewable companies, but would be interested to hear some first hand recommendations.

    We're also considering a SIP or ICF build potentially, so that will at least guarantee a well insulated building.

    Cheers!

    I'm not up on my building standards, but as far as I am aware the insulation standards in Ireland are poor at best but I could be wrong, I see new buildings built today with aeroboard in the cavity and a few inches of fibreglass in the attic and this is called insulation. However maybe your build includes more than the standard ? I am a big fan of spray foam insulation and would definitely have it done on a new build.

    I would get a quote for at least a 1KwP of solar PV setup , now at this time until the feed in tariff is introduced with some years guarantee of income and design the installation with the intention of adding a "lot" more when the ESB offer the Feed-In-Tariff because if you install a lot now it will go to the ESB for free. You can also think about a Tesla powerwall battery storage system to store excess power for later use by the house. It adds to the cost but maybe not as much as you think, a feed in tariff means you can send power to the grid and that becomes a gigantic unlimited free battery , you then buy back at night.

    You can get a solar PV controlling system that can divert the power to you hot water cylinder so you send any excess power to the hot water cylinder rather than the grid for free.

    So I would say even though solar PV is not required to meet Part L, but meets part L , then solar PV is a lot more beneficial than so much hot water that just sits there most of the time, again, solar PV can go a long way towards powering you whole house.

    Another important factor is if you have another form of heating that heats hot water then what's the use of solar hot water panels if they're really only useful for the few weeks of summer we get in Ireland ? It's just insane to think there is a grant for solar hot water panels but not solar Pv.

    Unfortunately I can't recommend any "competent" installers for either Solar PV or heat pumps.


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  • Registered Users Posts: 671 ✭✭✭ mrsWhippy


    Mad_Lad wrote: »
    I'm not up on my building standards, but as far as I am aware the insulation standards in Ireland are poor at best but I could be wrong, I see new buildings built today with aeroboard in the cavity and a few inches of fibreglass in the attic and this is called insulation. However maybe your build includes more than the standard ? I am a big fan of spray foam insulation and would definitely have it done on a new build.

    Agreed. We'll be doing this properly, exceeding the building regs and ensuring we have a warm, airtight house.
    Mad_Lad wrote: »
    I would get a quote for at least a 1KwP of solar PV setup , now at this time until the feed in tariff is introduced with some years guarantee of income and design the installation with the intention of adding a "lot" more when the ESB offer the Feed-In-Tariff because if you install a lot now it will go to the ESB for free. You can also think about a Tesla powerwall battery storage system to store excess power for later use by the house. It adds to the cost but maybe not as much as you think, a feed in tariff means you can send power to the grid and that becomes a gigantic unlimited free battery , you then buy back at night.
    Any idea how much these batteries cost? Any downsides to installing one of these, other than cost?
    Mad_Lad wrote: »
    You can get a solar PV controlling system that can divert the power to you hot water cylinder so you send any excess power to the hot water cylinder rather than the grid for free.
    Would it make sense to do this for just a 1kWp system though? Will there be enough 'spare' power to warrent a diversion system, with the fridge, MHRV, and Heat Pump using up a lot, if not all of it?


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