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powergen: average home uses 3300kWh electricity & 20 500kWh gas per year
BWEA: average home use 4700kWh of electricity
UK Gov: annual gas requirement 18000kWh

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PERFORMANCE OF MY SOLAR PANELS:

3x10tube 70mm panels:

Sunny Day in November -                   32C

Sunny Day in late December                29C

Sunny Day in January                          32C

Sunny Day at Beginning of February   35C

Sunny Day at the Beginning of March  50C

Overcast/sunny day Beginning of April 43C

Integral Cylinder type:
 

Produces steam in the afternoon from End February onwards.

CASE STUDY 1:

ABOVE GROUND POOL 7m x 4m x 1.5m; 2x 20tube panels (47mm)

up to 37C in mid summer, temperature above 20C until end November.

CASE STUDY 2:

preheat cylinder 135litres, 1x 20tube 47mm panel.

temperature up to 40C on sunny mid-February day.

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from: http://www.fujitaresearch.com/reports/solarpower.html :

Interseasonal storage III - storing sensible heat in water

In choosing a storage medium for collected solar energy, the use of water has many advantages over hydrogen and oxygen gas:

• it is unreactive and extremely safe
• it has an extremely low cost
• its high specific heat capacity means much energy is stored in a relatively small volume
• no toxic materials to deal with on future demolition work

As stated earlier, if water is to be used for long-term storage of solar energy, it must be stored in an extremely well-insulated container. In normal conditions, this means underground. To maximise solar gain on water heated, and to gain maximum benefit in using the water in radiators, care should be taken not to destroy the stratification that develops in the tank (whereby hot water moves towards the top of the tank and cold water towards the bottom).

Interseasonal storage in water I - office building case study

In 1998, the first results came in from a team of Italian researchers from the engineering Department of the University of Calabria, for the use of inter-seasonal storage in an office building in Northern Italy. Key statistics (shown in Figure 2) of the system are:

Solar collectors: 91.2 m2 vacuum-type heat pipes
Storage Tank: 500 m3 reinforced concrete with 0.2m foam glass insulation
Building Volume: 1750 m3
Heating Requirements: 111GJ

During the months between April and October the space heating in the building is shut off, and all collected solar energy is used to increase the temperature of the water in the underground storage tank. Assuming a starting temperature of 30°C, the water will be heated to more than 80°C by the end of October. During the winter months solar energy is still collected, but is insufficient to meet the heating demands of the building. Hot water is drawn from the top of the tank to feed radiators in the building - after the heat is extracted it is returned to the bottom of the tank. This thermal stratification is much more energy-efficient and means that the hottest water is always available for building heating, and the coldest water is always that drawn up into the solar panels (allowing maximum heat gain).

Figure 3 (below) shows the energetics for the house over the first year of operation. Points to note include the low temperature of the storage tank at the start of the experiment (11.6°C), which resulted in a maximum tank temperature for the summer of 71.6°. However, at the start of year 2 of operation, the temperature in the tank was significantly higher (more than 30°C) suggesting peak temperatures in excess of 80°C will be achieved. Another point is the loss of collected energy, even with high levels of tank insulation. Over the first year total losses were 113GJ of the total 257GJ collected at the solar panels.

Nevertheless the total efficiency of the system is 25%, comparable to the values obtained for thermal power stations. The experiment has clearly shown that interseasonal storage of solar energy as sensible heat is a practical method for creating energy self-sufficient buildings.

SOLAR

1. The 20 tube collector will be more than adequate for one person. However,
if you use it with a very large cylinder, you will end up with a lot of
lukewarm water instead of a small amount of hot water - so you need to make
a decision about the cylinder size, primarily. We normally recommend that a
20tube panel is used for tank sizes between 120litres and 170litres.
Obviously, the smaller the tank size, the hotter the water will be in
general, but the less water you will have stored. I would suggest you go for
something like a 135litre tank. This is slightly larger than a standard
water cylinder, so it would be perfectly adequate. You can go for a larger
tank if you wish, but do not exceed 170litres, unless you are planning to
fit more than 20tubes.

2.The Thermal coil 'whole house coil'  is a large version of a shower coil.
They have the same function, but the whole house coil can cope with much
higher flow rate. They are designed to allow mains pressure water to feed
directly through a very high surface area coil in the top of the cylinder,
thus heating the water almost instantaneously. They are quite expensive as
they are very large heavy copper coils (30-50% of the tank weight) - so it
is an expensive addition. It is, however, far cheaper than the mains
pressure cylinders.

3.We have been selling the solar panels for around 3 years. The panel design
has changed over its history, but it has been available for around 30years.
In europe and the UK in particular, it has never been popular due to its
cost. This is why we started importing and selling at much more realistic
prices, and coincidentally, solar panels have become more popular (perhaps
there is a connection?!)

4. We provide 1 year. The manufacturer provides a much longer warrantee
(return to factory), but we cannot offer this in the UK without taking out
Indemnity, which is basically an insurance policy to cover the cost of
replacement in the event of failure. This would add considerable cost to the
product, and I particularly do not want to increase the cost of the products
to allow insurance companies to get even richer.

5. The roof-mounting procedure is shown in detailed pictures on the
webpage - look at the solar page. If you do not want to drill holes in
tiles, the only alternative is to fit flashing/rubber kits. However, these
have rubber in them....what lifespan would you expect out of these? I prefer
silicone, as it seems to weather very well, and this method is very popular
with installers. However, if you do not like the idea, you can always run
the pipes along to the edge of the roof and send the pipes through the gable
end.

6. The triple layer insulation is around 75mm, however, it will tend to sag
a little more - so the insulation will not be quite so even.

7.Normally all the components are in stock. However I only carry a limited
number of tanks, as there are so many possible variations. Custom specified
tanks are available approx. 5 days after payment.

8. I do not offer discounts, except for large volume trade purchases. The
reason for this is that I have already offered massive discounts (afforded
by low profit margins). Just have a look at the competition and compare
prices.

9. Yes, I would be more than happy to supply you as a distributor.
Generally, I prefer distributors to purchase 10panels at a time, so that
they carry some stock. I can offer a discount for distributors (eg 20tube
panel £320). If you sell at the list price, you will make more profit than I
do on the sale. I can send you the full price list, if you are interested.

10. This is a very important question! If I do not believe in my own
product, what chance have I of selling it? I have indeed got a system on my
own house, and I use it for experimental purposes (which is not popular with
my wife!). Currently, it is a 30-single walled panel feeding a 260litre
vented cylinder with variable pump speed control.
 

GSHP