[Closed] Solar - On a slightly smaller scale

How many Kw are you going to get for £1.5k?

In a way he's right - the days of getting a good return on FITS have long gone, but if you're going to install panels, why not install as much as you can?
AFAIAA the actual installation will cost you roughly the same regardless of the number of panels - obviously lots of panels will cost a bit more but not that much. A small inverter will cost about the same as a 5Kw inverter, making the connections to your home supply will cost exactly the same.

Remember that if it's a cloudy day your 1Kw installation may only produce 150w which isn't really good for anything, while your 4Kw system would be producing 600w.

The future for solar is battery storage - when/if that becomes mainstream you'll be after all the production you can get.

150W could heat a bath's worth of hot water (roughly) in 16 hours. So a 2kW installation could maybe do it in a day in winter.

Side-track - does anyone do solar electricity to hot water storage, for heating purposes? Heat up a big tank of water nice and hot (with a big enough install) and then drive central heating from it with a heat exchanger.

Hmm, got me thinking now. Could easily home-brew that, given somewhere to put a tank.

...does anyone do solar electricity to hot water storage, for heating purposes?

my sustainability-consultant (my wife) says that solar-thermal would be a better bet, if your goal is to heat water...

Ah but if it's a cloudy day and only 5C outside, how hot can your solar thermal get?

Molgrips. "Google Solar power diverters"

My mate does this. I would if I didn't have a combi boiler.

Uh oh.. head full of ideas now...

As we live "off grid" we are currently speccing out a solar setup which will fulfill our demand throughout the year. Currently we have to run generators in the winter as the daylight hours and sunshine are insufficient. The consensus is that we need about 1500w of supply from 6 panels, a 24 volt storage system made up of 12 batteries each holding about 950mAh of juice and a 3000w rated inverter to turn this into 240V AC.
We're told this will satisfy our demand, the greatest user of electricity being the washing machine, unless the weather is dull for 3-4 days consecutively.
Big difference to other calculations is that we live in S Cataluña where it's sunny most of the time.

150W could heat a bath's worth of hot water (roughly) in 16 hours. So a 2kW installation could maybe do it in a day in winter.

Theoretically it can, in reality the house would be using this much power in the background (fridge, freezer, clocks, oven, wifi, TV, etc), plus the natural losses of the heating system would mean that you wouldn't get much hot water at all.
I do have some background in this as I have a 3Kw installation with a proportional diverter that heats the hot water and it works great between May and Sept but not so well in the other months - and that's in a small second house with only a fridge and wifi running most of the time as there's no-one there.

Solar thermal is an option but isn't as ubiquitous as it can only do one thing, can be slightly tricky to install i.e. needs power for a continuously running pump, a separate tank to take excess heated water, plus it introduces a layer of potential problems to your roofspace (water flowing around).

For those that are interested in this sort of thing you should go and have a look at the [url= http://www.navitron.org.uk/forum/ ]navitron forums[/url] - loads of very knowledgeable people there.

The consensus is that we need about 1500w of supply from 6 panels

PB .... where abouts are you? If you want some real production figures you can look at the output of my [url= http://pvoutput.org/intraday.jsp?id=6085&sid=4867 ]4Kw system in Chester[/url] - from this you can see what we actually get.
Def check out Navitron also.

Grips: air temp is not what heats solar thermal. Insolation is.

If you put the tank above the solar panel and use 18mm+ tubes all around the circuit it will thermo-syphon so no pumps or electricity are needed. With solar thermal it's best to have two tanks. In Winter the solar system tank serves as a pre-heater for the second electrically-heated tank so you get some benefit in December.

I feed the washing machine from the solar tank on the fill cycle. This requires turning valves next to the washing machine to get the right fill temperature (and avoid rinsing with half a tank of hot water). After 8 years Madame still asks which way to turn them (they are marked). When low tech is still too high tech.

Temperature varies from 65°C+ in Summer to a few degrees above mains temperature in December. The only time it doesn't work at all is when there is snow on the panel. We're 43°N

Over the year it has reduced the electricity consumed in water heating by about 2/3. I could have made a similar saving with a hot water tank with a built-in heat pump. I like the low-tech approach and the fact that maintenance is limited to cleaning the panel and topping up the header tank once a year.

To be fair Edukator your location renders some of your data not very useful for UK dwellers. For example, I have never seen a tank set above the solar panels in the UK whilst they are commonplace in the [preferably] sunnier/warmer parts of Europe.

That's why I gave my latitude, Sharkbait. We're near the mountains so the sunniest bits of England get as much sun as we do but the sun is always higher in the sky here, 9° compared with Birmingham, so our panels get as much sun in October as they would in September. I'm still on solar showers which are getting tepid but would have had to switch on the electrical heater sometime in September in Birmingham.

Grips: air temp is not what heats solar thermal. Insolation is.

Yes I know but the colder the air the more heat is lost in the panel.

And conversely PV performs better in colder temperatures.