Total Newbie , What do I Need ?

Saab Ed

Just back from a trip across Europe where we've seen a huge amount of solar panels - in particular in Germany - where they seemed to be everywhere. Entire roofs where covered in solar panels and it didn't stop at houses , sheds , farm buildings , even propped up on fences at the end of gardens.

Anyway we'd being talking about doing this for a while and seeing the high use of it in Europe we decided to get the ball rolling. We're putting in under floor heating soon and we're going to try and do the two together. We currently use gas to heat the house and for the cooker. I was thinking would it be possible to ditch the gas altogether and just run the heating and hot water from solar energy alone. ( I could switch the cooker to electric and that gets rid of my gas bill completly ) .

What type of equipment do I need to do this , I really am just starting out asking questions about this , I know nothing about how it works and what I need. Also what sort of cost am I talking about here. If im going to do it then I'll go the hog or is it worth my while to try and copy the German examples I've seen with the entire roof covered in panels.

Thanks in advance everyone,

Ed.

quentingargan

Hi Saab Ed, I suspect some of the solar panels you were seeing (especially at the end of the garden) were photovoltaic panels generating electricity. Some countries (including the UK now) offer incredibly generous feed-in tariffs for selling electricity to the grid - 45c per KwHr in some cases, even though the selling price for this electricity is a third of that.

That isn't an option in Ireland, and I'm not sure I would want such generous tariffs to subsidise a PV industry here.

What does make some sense, particularly if you are looking at doing a major renovation of your plumbing, is a modest solar water heater to provide your domestic hot water. I personally can't see that it makes any sense to use solar panels to heat your house, as they work best when you need them least. You will find dissenters from this view on Boards if you scout around a few other threads here (or they will find you if you wait a while).

In the summer time, when the heating is off, your hot water tends to be more expensive, because it usually comes from an immersion, or by running a boiler very inefficiently for a short period just to heat a poorly insulated cylinder in the hotpress. Solar hot water displaces the most expensive hot water in these cases.

Ratcheting up to a huge solar array, buffer tanks etc., produces a lower return on investment, and usually there is lower hanging fruit in the form of insulation and other options to reduce heating demand.

Q

Saab Ed

quentingargan wrote: »

Ratcheting up to a huge solar array, buffer tanks etc., produces a lower return on investment, and usually there is lower hanging fruit in the form of insulation and other options to reduce heating demand.

Q

Great advice.

Right so what should I be looking to buy and where should I be looking. Lets say , like you said , just to heat the hot water for the shower and the like. Plus can I benefit from any additional devices i.e small windmill on the side of the house etc. If im doing this now then I wont be doing anything like it again for a good long while so i'd like to make the most out of what im doing.

Just on the other thing you pointed out about the Germans selling electricity back to the grid, is something like that likely to come into effect here in the short to medium term and if so can I be prepared and fit some bits the I might not need just yet but that might just leave me with very little work to do whan the time comes.

quentingargan

Saab Ed wrote: »

Great advice.

Right so what should I be looking to buy and where should I be looking. Lets say , like you said , just to heat the hot water for the shower and the like. Plus can I benefit from any additional devices i.e small windmill on the side of the house etc. If im doing this now then I wont be doing anything like it again for a good long while so i'd like to make the most out of what im doing.

Just on the other thing you pointed out about the Germans selling electricity back to the grid, is something like that likely to come into effect here in the short to medium term and if so can I be prepared and fit some bits the I might not need just yet but that might just leave me with very little work to do whan the time comes.

Hi Ed,

I can't recommend suppliers on the board, and everyone has their preferences in terms of tubes -vs- flatplate. But in general, the norm would be to get a cylinder that stores roughly 50L per person in the household. Then the size of panel depends on a few things;

• How much of the season you want to have solar hot water (I have a well insulated house and try to get about 8 months coverage, whereas poorer insulated houses with the heating on in Spring and Autumn might be happy with a smaller panel that supplies your needs for 5 to 6 months)
• Whether the house is occupied during the day (you may use more hot water, but require less storage)
• Whether roof is facing south or now - you would need about 30% larger panels for east / west facing roofs, depending on roof pitch
• Distance from Panels to cylinder
• Geographical location (Donegal may need larger panels than Wexford).
• Hard or soft water? Hard water can only be stored at 60 degrees, but soft water can be stored up to 85 degrees, so you can store more "heat" with soft water.

If you PM me your details, I can get a computer simulation done for your site.

Flatplates have the advantage of being very durable (40 years) and more aesthetically appealing than tubes. Tubes are better insulated and work better at the fringes of the season, so if you want spring/autumn supplies they are better. You will usually have to replace the glass part after about 20 years as the vacuum fails. With the Chinese ones, this is a cheap replacement, but other glass tubes with integrated heat pipe are a lot more expensive to replace. Tubes also break easily if you're a Kilkenny hurling family, but if you ever actually DO break a flatplate, it'll cost yer!

Windmills on the side of a house are nonsense alas. The wind is far too turbulent close to houses, and this turbulence decimates the output of a wind turbine.

If you think there are going to be huge feed-in tariffs for PVs, you could wire double-insultated 6mm stranded wire from your attic to a point close to your fusebox where a grid-tie inverter might be fitted. If you are fitting vacuum tubes, you will have a venting slate to bring the pipework into the house, so that can probably accommodate the cabling.

Q