Solar water heating

[Brian Ellis]

I've been very satisfied with our solar heating that came with the house and was obviously a bottom-of-the-range. Because it took 2 min for hot water to come to either of the bathrooms and 3 min to the kitchen and downstairs guest toilet, I recently put in a hot water recirculating system, so that hot water came out of the tap/shower quasi-immediately. This was fine on very sunny days, but the extra heat losses meant that it was barely adequate on less sunny days.

I decided to call in an expert with a view to more joules on the input side. He carefully examined the 12 year-old system and reported a) the cold water tank was in plastic and was a little on the small side for when we had visitors b) the hot water tank was dimensioned for a small household (2 persons) and c) the solar panels were also dimensioned for a small household and were in plastic. He recommended replacing the whole caboodle with a 750 l cold water tank, a 180 l HW tank and 50% more solar panel in a more efficient design with blackened copper pipes soldered onto a 5 mm copper plaque and double-glazed glass, instead of single plastic, along with new supports to be welded onto the existing ones.

I saw €€€€€ signs in front of my eyes, but was pleasantly surprised when I received the quotation: €1,500, including 15% VAT, installed and guaranteed ready to run with only 4 hours without water to the house. With the price of electricity today, the alternative of 100% immersion heating, say 4-5 kWh/day, it will be amortised in <5 years, not counting that electricity will inevitably increase in price, as it is all oil-generated here.

[TransformX]

It's not very pretty to the sight, but here almost everyone uses solar panels for water and it's rather cheap.

The whole thing costs less than €1,000 for the high end and less than €500 for the standard stuff (installation included).

[Umfriend]

And AFAIK, in Israel it's been like that for ages (well, figuratively speaking), at least from the 1970's but it may have been decades before that even.

[Brian Ellis]

Attached is our present installation. You can see that the plastic framework of the RH panel has distorted through exposure. The CW tank is on top and the small HW tank underneath. This is quite typical of most installations here with the 2 tanks, which explains the difference in price with the Israeli system. I agree that neither is elegant!

Cyprus was actually the pioneering country for solar water heating. We used it when I was here in 1952/3, although it was not very common, then. It received a boost in the 1960s when there was a severe electricity shortage, following independence. Today, they boast that it is the most solar country in the world with over 97% of households and industry having solar hot water.

The new system (made to measure, hence delay) will be installed in a couple of weeks: I'll post a photo for comparison.

[Fat Tone]

I wish I could do that here. Sadly none of our roof surfaces face due-south and at our lattitude I don't thing anything else is even worth considering. Roofs are generally traditional slopes here so anything other than panels laying flat on them would be very unsightly and unlikely to get planning permission.

[az]

Wow, that's ugly. I'll post a picture of my parents' solar water heating roof when I get around to and if I remember it. I think it was much more expensive, though (everything related to house building is expensive in germany)

[Brian Ellis]

Of course it's more expensive in Germany. You must have an indirect system with a large heat exchanger, more losses, antifreeze-resistant metalwork, larger panels to compensate for the extra thermal losses because it is indirect and also for the extra 15° in latitude, etc. As a guess, I'd price one for Germany at €7,000-8,000, as against €1,500 here for a top-of-the-range direct system.

[TransformX]

[Jammrock]

You get enough sun in Sweden to use solar heating?

[dZeus]

You get enough sun in Sweden to use solar heating?

The greenhouse effect must be very busy in Sweden then! Look at those trees in the background

[cjolley]

The greenhouse effect must be very busy in Sweden then! Look at those trees in the background

You've never seen a Swedish Coconut Palm before?

[Brian Ellis]

OK, it's still fugly, but it does work a lot better with 50% more panel area.

The installation took 3 guys 5 hours with a whopping great crane with a 20 m jib!

[TransformX]

And there I thought the local breed looked bad...
Why the cold water tank?

[Brian Ellis]

a) to store water for when there is no incoming water (currently, we get incoming water 3x/week for a few hours because of extreme drought conditions)
b) to provide sufficient pressure, by gravity, to have a decent shower
c) as a vestige of colonial rule, when the Brits decreed that check valves were not reliable enough in the event of a drop of incoming pressure, so that it was necessary to have a ball-cock to prevent reflux of tanked water back into the mains.

Because the installation is bigger, we now get about 50 cm higher water head: it makes a difference in the shower, from an estimated 3.0 m to 3.5 m to the level of the shower head.

Anyway, we now have immediate hot water, at the turn of a tap, whenever we need it, without wasting any water waiting for it to run hot (in the kitchen, it used to take 2¼ min).