solar and gas option

JD6910

anyone have any thoughts on the option of installing a solar system along with a gas central heating system in an A rated super insulated home?



i assume the running costs will be very small in an A rated house?

the house will also have a room heater stove.

quentingargan

If your house is A rated, I would opt for tubes rather than flatplate to get a longer heating season. Then the gas would (mostly) only be required to heat water in the winter when it might already be used to heat the house for a wee while.

Tubes generally are better in spring and autumn than flatplates. Using gas just to heat water when it is not otherwise needed for central heating is quite a bit less efficient, unless you are using a combi boiler.

JD6910

quentingargan wrote: »

If your house is A rated, I would opt for tubes rather than flatplate to get a longer heating season. Then the gas would (mostly) only be required to heat water in the winter when it might already be used to heat the house for a wee while.

Tubes generally are better in spring and autumn than flatplates. Using gas just to heat water when it is not otherwise needed for central heating is quite a bit less efficient, unless you are using a combi boiler.

am i correst in saying that the solar will do some of the hard work and the gas is then just bringing it up to temp?

the solar will do its best at any given time and the gas will do the balance.

i think my heat demand is 13000KW/hr per yr. this is small i think???

quentingargan

JD6910 wrote: »

am i correst in saying that the solar will do some of the hard work and the gas is then just bringing it up to temp?

the solar will do its best at any given time and the gas will do the balance.

i think my heat demand is 13000KW/hr per yr. this is small i think???

Yes - you are correct in this. But to be honest, the savings in winter are modest enough because the solar gain is reduced and it is displacing gas central heating which is already quite efficient, but you will see small savings, even on somewhat overcast days, when the solar might bring the cylinder up to 30 or 40 degrees.

Depending on the house size, 13MwHrs per year might be A rated. A3 is up to 74.99 kwHrs per sq m per year. If your house is larger than 175 Sq M you would scrape in as an A3. Q

DaveSave

Solar and heating systems

One of my work colleagues is a mech&Elec Eng and has done that masters in renewables in Dundalk he is a legend on this stuff

The sun is suppose to produce on average 1000 kw/hrs a year in IRL. The best panels harness 630kw/hrs a year per square meter (Tubes (flat plates are at 280 - 440)) 1, so if you used ten square meters thats 6300 kw/hrs a year but but but 60 - 70% of this is in the summer when you dont need it. We where quoted €18000 for a solar heating system which would have saved us about 4 - 8% of our bills.
We could of bought a chimney ballon for €25 which would have saved the same percentage.

Its a thermal store/combination tank your looking for with solar coil/stove coil/boiler coil air sourced heat pump? coil.

quentingargan

DaveSave wrote: »

Solar and heating systems

One of my work colleagues is a mech&Elec Eng and has done that masters in renewables in Dundalk he is a legend on this stuff

The sun is suppose to produce on average 1000 kw/hrs a year in IRL. The best panels harness 630kw/hrs a year per square meter (Tubes (flat plates are at 280 - 440)) 1, so if you used ten square meters thats 6300 kw/hrs a year but but but 60 - 70% of this is in the summer when you dont need it. We where quoted €18000 for a solar heating system which would have saved us about 4 - 8% of our bills.
We could of bought a chimney ballon for €25 which would have saved the same percentage.

Its a thermal store/combination tank your looking for with solar coil/stove coil/boiler coil air sourced heat pump? coil.

Solar doesn't work for space heating - it provides the energy when you don't need it. A 10 m system would be lunacy, and €18K for it is even madder.

But a 4m system for about €4K (which is where the market is at) will provide your hot water during the summer when the heating is off, and this is the period when your hot water is most expensive, becasue often it comes from the immersion, or by running the heating system very inefficiently.

In that case, 4m at 630KwHrs per meter (your figures, not mine) would save about 2500 Kw Hrs per year. Say 2/3rds of that is displacing the immersion at 16c and the other 1/3rd is displacing gas at 8c, that is a saving yearly of €336. With the grant of €800, it all starts to make sense.

JD6910

i suppose ultimately all i'm asking the solar to do is hot water. Anything after that is a bonus!!! no worries about the summer and looking forward to my free hot water. in winter, i expect the solar to do its best and then the gas cut in to top up the tank.

the question i am asking is:

in your opinion what will be the cost/usage of gas in a super insulated 3000 sq Ft home. not expecting exact figures - just opinions.

house has:

200MM pumped cavity, triple glazed windows - large windows south and small windows facing north, windtight and airtight construction. 150MM metac, airtight barrier and 62.5mm insulated slab in the roof, room heater stove.