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Domestic Solar PV Quotes 2020
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Then when the current house demand, car charging, hot water and any battery store are all filled, the excess goes under the ground to warm the floor area and reduce the heat demand from elsewhere.
I haven’t read the paper so tell me go read it if the answer is in there!
Any excess you have will be in summer. What use is heating the ground then when you won’t need that heat for months later. It will be long gone and possibly result in a house that’s too hot as the heats rises up through your floors like underfloor heating does.
Can you give me the crash course on how this works.0 -
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A 3m deep hole with 50mm dia has a volume of 6litres. You sure you did not mean 500mm diameter? Even with 500mm you are only talking 600 litres. Let's assume you heat that water to 90C and then use it all the way down to 20 without any heat loss between the seasons. Wildly optimistic I know but bear with me. That is a total energy of 49kWh. I don't see how you save any money at all doing this.
And no way you maintain that temperature from summer to winter without loss. Please check the maths before sinking a 1000 euro in this project. It is looking less and less economically feasible. You will probably save a tenner off your bill every year.
Garo, perhaps you are taking a different view to me concerning how it works. I never intend to heat any water this way, directly or instrumentally.
I want just to stand the house atop a very slowly cooling warm slab of clay and rock. That's the basic idea of seasonal thermal energy storage. You heat it up, and it blocks off conductive loss through the floor area, or even adds something back into the living space. That would depend on how deep the source of heat is set into the soil.
So if I bump up that figure, that's less flowing from the house back down through the foundations, and will lower the overall heat demand. Ground temperature year on year is around 8 deg C I think. I don't see it happening that I will create a discomfort inducing hotspot without long advance flagging. I should have loads of time to tweak the depth and quantity of heat dumping. You may be aware there are heat transfer math equations and calculation procedures to analyse this, that are used in reactor core design, but hey this is supposed to be a low key project!
Over time, it may/will act as a big thermal flywheel. It depends on what my excess is. If not much excess heat energy flows in, I wouldn't think it would be all that discernible of a difference, like say my system was at the low end of what is normally fitted to a roof.
But I will be using an adjacent good sized field with good clear aspect. And lots of panels. If I size my panels for a longer seasonal cycle of conventional usage, it will be like living over a huge low temperature underfloor storage heater, or a volcano, without the eruptions
Obviously at this point I don't know the calorific banked capacity of the soil with any precision; its why I am adopting a suck it and see approach. Blessed are they that don't expect, ...
IIRC a semi D loses about 30% of its heat through the floor, it ought to be a higher proportion in the case of a bungalow.0 -
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Garo, perhaps you are taking a different view to me concerning how it works. I never intend to heat any water this way, directly or instrumentally.
I want just to stand the house atop a very slowly cooling warm slab of clay and rock. That's the basic idea of seasonal thermal energy storage. You heat it up, and it blocks off conductive loss through the floor area, or even adds something back into the living space. That would depend on how deep the source of heat is set into the soil.
So if I bump up that figure, that's less flowing from the house back down through the foundations, and will lower the overall heat demand. Ground temperature year on year is around 8 deg C I think. I don't see it happening that I will create a discomfort inducing hotspot without long advance flagging. I should have loads of time to tweak the depth and quantity of heat dumping. You may be aware there are heat transfer math equations and calculation procedures to analyse this, that are used in reactor core design, but hey this is supposed to be a low key project!
Over time, it may/will act as a big thermal flywheel. It depends on what my excess is. If not much excess heat energy flows in, I wouldn't think it would be all that discernible of a difference, like say my system was at the low end of what is normally fitted to a roof.
But I will be using an adjacent good sized field with good clear aspect. And lots of panels. If I size my panels for a longer seasonal cycle of conventional usage, it will be like living over a huge low temperature underfloor storage heater, or a volcano, without the eruptions
Obviously at this point I don't know the calorific banked capacity of the soil with any precision; its why I am adopting a suck it and see approach. Blessed are they that don't expect, ...
IIRC a semi D loses about 30% of its heat through the floor, it ought to be a higher proportion in the case of a bungalow.
Thanks for the reply. Yes I was thinking of a different system than one you had in mind. So my question is how do you stop the thermal mass from losing heat from the 4 sides and the bottom rather than the top? What insulation if any do you you around the five sides of your thermal store? With a long narrow tube like you envision, far more of the area is to the sides and bottom than to the top. Here is an old but relevant thread from GBF UK: Interseasonsal solar thermal storage
and
passive-house-with-no-tapes-membranes-no-ducts-no-back-up-heating-system
In summary: a long narrow tube is probably a bad way to go about it. You are better off with a flat horizontal slab. Resistive heaters are notoriously inefficient and you would get about 5x more heat output with solar thermal tubes. Without the thermal store being insulated I suspect you will lose so much from the sides and bottom that you won't get that much usable heat out.
PS: Spend that thousand on better ground insulation will probably get you a better return. I'm assuming this is a new build?0 -
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