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Author Topic: Thermal Solar Panel DIY Project for domestic hot water under 100  (Read 38300 times)

Offline Andrew K Fletcher

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Click on Link For Slide Show:

70cmx45cm timber   2 lengths 214 cm  2 lengths 81cm mitred grip fixed and screwed to form the frame to house your solar panel.

2 lengths of 3x5cm to support galvanised corrugated sheet sides

I standard corrugated tin roof sheet  (recycle centre 5.00) overcharged me IMO J

Black foam backed reflective foil faced thermal lagging (lucky find in recycle centre 2.00) This is used on the underside of the corrugated steel sheet to prevent heat escaping from the back of the panel. (pictures to follow)

Perspex cover sheet. A used aluminium window and frame can do the same job. This is to provide a heat retaining shield to let the energy in from the sun and prevent the heat escaping from the mat black painted corrugated sheet an copper tubing carrying the domestic hot water.

2x 3meter lengths of 22 mil copper tube
6x 3 meter lengths of 15 mm copper tube
16 x   22mm reducing Tees to 15 mm middle outlet fittings
4x 22 mm elbows
2 15mm sockets to join offcuts to save on copper tubing requirements.


Make wooden frame mitre the ends, grip fix or wood glue and screw ends together

This should be made so that the corrugated sheet fits inside with ease, the bottom and top edges of the sheet are cut with tin snips and bent to a right angle. Screws can be hammered through the thin sheet to secure the top and bottom.

The 2 lengths of 3x5cm are nailed flush with the edge of the frame on both sides. The corrugated sheet is inserted and secured by hammering screws through the sheet, best done with a screw driver and hammer, then wizzed up with the powered screw driver after you have lagged the back of the sheet with the reflective foam backed lagging. This way the tin sheet secures the lagging and the sheet in one go. Allow sufficient lagging to hang over the sides of the frame so that the Perspex/ glass lid can be secured to form a nice weather proof gasket.

Once the frame is lagged and secured with screws along the sides and the snipped corrugated ends of the sheet are folded over these can be secured again by driving the screws through the thin sheet into the wooden frame with a hammer.

Now for the soldering bits n bobs.

The 22 mm tube is for the outer edge fitting inside the timber frame sides, top and bottom, with an outlet via a Tee converter at the bottom and on the top at the opposite side giving maximum distribution of the inflowing cold water (bottom) and out-flowing hot water (top opposite side)

Each corrugation on the tin sheet will have a 15 mm copper pipe joined at the top and bottom by a reducing Tee fitting. Repeat until all corrugations have a 15 mm pipe. When all the soldering is checked for leaks under pressure by linking to the mains via a jubilee clip and hose pipe or whatever method you choose and you are certain there are no leaks.


Spray paint the sheet surface and pipes with mat black heat resistant stove paint or exhaust paint. This is going to get hot quickly.

The idea is using aerosol paint we can have a very thin mat black surface to maximise heat transfer to the water inside the tubes.

Secure the Perspex / glass lid in place and couple it to either an indirect heating system or a direct heating system making sure there is an expansion tank on the system to take care of increased pressure building up as the water expands when heated and does not compress. I used plastic lugs shown in picture to secure the perspex sheets as they are prone to crack if drilled and screwed

Adequate lagging and an outside isolating stop cock and drain plug for those freezing winter nights might be a worthy consideration.

My system hopefully will run solar heated water back to my combi boiler, which fingers crossed should not have to fire up and if it does fire up will shut off once the heated water reaches the internal thermostat. Though on sunny days, we should have hot water with the boiler turned off.

Early days yet and more modifications may be required, but thought you might be interested in this project designed to supply our hot water needs.

This total build is costing under a hundred pounds!

My philosophy is if I put a hundred pounds in the bank, by the end of the year, given the pathetic interest rates and poor performance of the pound against the euro, I will probably have lost money.

Here my hundred pounds will earn me money every time we have some moderate sunlight.

Andrew
« Last Edit: 29/05/2009 23:03:36 by Andrew K Fletcher »


 

Offline RD

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I've seen old radiators (the lightweight pressed-steel type) painted black and used in reverse as solar panels to heat a greenhouse.

However the annual average insolation in the UK is only about 100 Watts per per square meter.
 Bear in mind solar panels are not 100% efficient, (the photovoltaic ones are only about 10% efficient).


BTW Anti-freeze will be required if there is a chance of frost.
 

Offline Andrew K Fletcher

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My aim is to pre heat the water that goes to the boiler to save energy. I have seen some pretty impressive simple applications using mat black finishes. One video on Youtube shows a simple coil of black plastic pipe being used on top of a steel cladded garage roof, producing hot water on demand as the water flows through the long coil.

While in Majorca, a friends home had a black plastic dustbin, fitted with a ballcock valve on his roof. This supplied all their hot water for the home during the day.

My system should be fairly frost proof having a thermally insulated back and sides and a thick perspex front, with lagged pipes to and from it. There will also be a stop cock and drain valve to empty the system should the weather become very cold. Also considering having a coil of black plastic pipe around the outside, this would provide an increased amount of warmed water as in the Youtube video mentioned, but will also provide an expansion mechansim when the pipe and panel warms up or for an unexpected freeze during the winter.

We have similar plastic pipe outside that does not become affected by frost. Living in Torbay helps as temperatures do not drop as much due to the warm gulf stream air that circulates all year round.

Thanks for input
« Last Edit: 22/04/2009 10:52:24 by Andrew K Fletcher »
 

Offline Andrew K Fletcher

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http://s209.photobucket.com/albums/bb31/Andrew_K_Fletcher/DIY%20Thermal%20Solar%20Panel/?albumview=slideshow  some photographs of panel



The coil of black mdp pipe was obtained from the recycle centre. This will be coiled tightly to lay flat on my conservatory roof so that the cold water supply will circulate through the plastic tubing and pre heat before entering the solar panel. This should provide me with sufficient hot water for most domestic chores without the need for the boiler to be turned on during the summer months.

Here is a video using just the black plastic pipe. http://www.youtube.com/watch?v=sBAi_TVNaiM

Originally thought of using a stainless cylinder that would act as an expansion tank, then got to thinking about mdp plastic pipe. This stuff is used for irrigation and survives frost and heat all day and avery day. So should provide me with expansion as would become more supple when hot and would provide hot water also. :)

http://www.youtube.com/watch?v=UXGlB1kGO5E Click to View Funny Video of man fighting a huge black plastic snake.

"A Team" looking for a new member?
« Last Edit: 07/05/2009 11:29:17 by Andrew K Fletcher »
 

Offline Karsten

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Lucky find, this black plastic pipe. I am looking for this for a while now to build a solar shower.
 

Offline Andrew K Fletcher

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Karsten, this pipe can be found in Farmers spuppliers as it is used in irrigation. Not that expensive either.

I paid 10.00 for about 50 metres, it did have a stopcock fitted already which was a bonus.

Video showing plastic pipe capabilities:

140 degrees water temperature.
« Last Edit: 07/05/2009 11:46:55 by Andrew K Fletcher »
 

Offline Karsten

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Karsten, this pipe can be found in Farmers spuppliers as it is used in irrigation. Not that expensive either.

I paid 10.00 for about 50 metres, it did have a stopcock fitted already which was a bonus.

I have a friend who keeps all sorts of stuff. Acres of it. I will ask him first. I do like the idea of recycling stuff that gets thrown out by others. Why buy new if you can get it used? Well, yeah, it is better for the economy to buy new. Anyhow, until you mentioned it I did not think of this material. I was always looking for black garden hose.
 

Offline Andrew K Fletcher

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Finally have the Solar Panel fitted to the feed for domestic hot water and appears to be running OK, although rather cloudy today and raining a lot so unable to determine the temperature of the water. Looking forward to running hot water without boiler being used at all during sunny days if it goes to plan.

Had hell of a game reducing the black alkathane 18mm od pipe to 15mm copper. Had to buy 20mm mdp fittings, which worked. Should have got black mdp pipe from plumbing suppliers. May have to do this later depending on whether extra heat from sun causes the fittings to part with the copper pipe.
 

Offline Andrew K Fletcher

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Ouch. The sun came out today :) Boiler was turned off and the water coming out of the solar panel was far hotter than the normal hot water from the boiler. With the boiler turned on, it fires up and then turns off immediately the solar heated water reaches the thermostat Amazingly simple to set up, compliments the combi boiler perfectly and runs hot water to the taps without the boiler on a warm but overcast day. Not bad for under a hundred pounds.

Now, because the washing machine is cold feed only, need to fill the washer with around 3-4 kettles of free solar heated hot water :) Therefore saving on electricity too......

Andrew K Fletcher
 

Offline Andrew K Fletcher

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Solar panel is now fully functional


Solar Panel connection to Boiler. Note during sunny days, boiler is switched off as no longer required. On cloudy days, the solar panel suplements the boiler reducing the amount of gas required to heat the hot water to the taps/


Solar Panel connected via the black plastic coil that pre heats the water entering the solar panel as shown previously. The cold supply was T'd in to the outside cold water tap 15 mm pipe.

 

Offline daveshorts

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Good project Andrew, if I am ever rich enough to own my own house I would like do do something similar.

You may want to do a couple of things that will increase the amount of the year that it will work for..

I would insulate the hell out of all the hot water pipes getting down from your panel, or on a cold sunny day you will loose all the lovely heat your panel has produced heating up the air.

I would also worry, especially in Brixham, about rain getting into the panel and you using all your heat to dry out the panel rather than heat your water. And you will get condensation on the inside of your glass, reducing its transparancy...

I guess the bigger problem is that you will have to shower when the sun is out... but I guess adding any form of hot water tank style heat store is going to be expensive...

I am really tempted by some sort of parabolic trough based solution. As then one gets the fun of making it follow the sun, and of course it will concentrate the sun more and work for more of the year.
« Last Edit: 06/05/2009 13:58:51 by daveshorts »
 

Offline Andrew K Fletcher

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Hi Dave

Already insulated the pipe, going to paint the insulation with a black ruberoid coating so the outlet pipe is also working with the sunlight and it will add a little more insulation as you rightly suggest.

The rain getting in presents no problem as the slope causes the water to drain through the lagging at the bottom of the panel. Also pretty much rainproof.

Re parabolic trough: Corrugated sheet provides a nice solution and makes sure that the suns direction is always captured and the heat is efficiently delivered to the pipes. This system works very well. We can't put our hands under the tap, even when the sun has been out for 20-30 minutes. I can't believe how efficient this simple system is. The black coil of plastic tubing provides an expansion tank and also generates a surprising amount of heated water, this enables the solar panel to heat the water faster.

RE Hot water tank. The type with the header tank above the main H/W tank (modern type) are heavily lagged and have a copper coil inside them. These can be obtained again from the local refuse tip or recycle centre. The last one I got from there was given to me free because it was too much trouble for them to remove the heavy foam lagging.

Was reading one of your posts on the ms theory thread. Have added a lot of press cuttings and some additional letters that you might find interesting. Also been reading through the data / feedback I have relating to ms, Something should be done with all of this data with regards to publishing.

Andrew
Good project Andrew, if I am ever rich enough to own my own house I would like do do something similar.

You may want to do a couple of things that will increase the amount of the year that it will work for..

I would insulate the hell out of all the hot water pipes getting down from your panel, or on a cold sunny day you will loose all the lovely heat your panel has produced heating up the air.

I would also worry, especially in Brixham, about rain getting into the panel and you using all your heat to dry out the panel rather than heat your water. And you will get condensation on the inside of your glass, reducing its transparancy...

I guess the bigger problem is that you will have to shower when the sun is out... but I guess adding any form of hot water tank style heat store is going to be expensive...

I am really tempted by some sort of parabolic trough based solution. As then one gets the fun of making it follow the sun, and of course it will concentrate the sun more and work for more of the year.
« Last Edit: 06/05/2009 19:30:09 by Andrew K Fletcher »
 

Offline Andrew K Fletcher

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Measurements are totally flexible, depend mainly on the size of the corrugated tin sheet you decide to use. You can source all of the copper pipe and connections second hand from your local scrap yard or from the recycle centre. You will need to borrow if possible 2 copper pipe cutters a 15mm and a 22mm, or the type that relate to US pipes..

As you are using this system for domestic hot water rather than drinking water, I preferred to use 60/40 tin-lead solder as it is far easier to work with. Good flux is essential so you will need to source this by asking a plumber and tell him/her what type of flux you will be working with. You will also need some wire wool to clean the joints prior to soldering, even on new pipe this is advisable as saves lots of hassle later.
As I said before use only the cheep copper pipe connections / joints as these solder far easier than the type with the ring of solder inside them.

A canister blow lamp are inexpensive, and at a push you could even solder the joints on a gas cooker ring, or even a gas camping stove I have in the past. Anything to save a buck.

Our corrugated tin sheets are 7 feet x 4 feet so this was the size of my panel and works well.

The idea of using 15 mm tubing for the heat exchanger / radiator inside the cabinet is that it contains more water and compliments the combi boiler perfectly. The coil of black pipe doubles up as a heating source and also an expansion tank as the plastic becomes more supple when warm so can stretch to relieve the extra pressure. Although an expansion tank could be connected also and again can be obtained from a plumber who probably has a few of these second hand laying around and will be very interested in your DIY solar Panel.

The mat black stove paint cost around 3.40 and by spraying the copper tubes (after they have been pressure tested for leaks) on top of the corrugated sheet both sides, you will find you can just about cover the rest of parts of the sheet missed by the overspray. Alternatively, buy 2 cans as I am quite an experienced car refinisher :) The paint is essentially the most important part, so choose the right paint. Open fire stove paint is the best because it is thin and does not inhibit heat transfer and is readily available in most diy stores.

« Last Edit: 07/05/2009 10:14:01 by Andrew K Fletcher »
 

Offline Andrew K Fletcher

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I used a frosted type of perspex as this appeared to be warmer when held up to the sun (experimented with glass, clear perspex and frosted) Frosted won the day, besides for 3.00 at the recycle centre who was I to argue :)
« Last Edit: 07/05/2009 10:15:00 by Andrew K Fletcher »
 

Offline Andrew K Fletcher

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Now we have some sunshine at last, it takes 15 minutes to provide hot water, when the system has been run until cold water flows. Yes, 15 minutes to provide very hot water. What I suspect is happening is that the steel sheet and thermal lagging hold on to sufficient heat to return it rapidly back to the water inside the copper radiator. Also, have now removed the wood from the underside of the large black tube coil on the flat roof, affording it to come into contact with the black roofing felt. A noticiable difference in performance has been observed sinse doing this.

Next step is to purchase a header tank for the top of the panel, this will porovide 20 litres more hot water. Adding to this a thermostatically controlled bath mixer tap that provides an additional shower, hooked up to the solar panel and combi boiler combination.

Have great expectations with how much money will be saved using this system.

All domestic hot water now provided free even when cloud cover is frequent, providing 15 minutes of direct sunlight hits the panel, we have hot water.
 

Offline Chemistry4me

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Whoa nice, now you've really got me thinking.
 

Offline Andrew K Fletcher

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Will be reporting back on the shower as soon as modified the system to include a tenk.

Here are the costs invloved minus the tank, new thermostatic mixer shower tap and couplings.

Corrugated sheet        5.00
Lagging silver          2.00
Fittings       20.00
Pipes         55.00
Plastic connectors   6.70
Perspex      10.00
Black plastic pipe   10.00
Black spray paint   3.75
Miscl fittings          3.00
Pipe laggings      1.50

Total cost including all external plumbing 116.90
 

Offline Andrew K Fletcher

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At present the contents of the coil of tube can hold sufficient water to fill the automatic washing machine using a jug. This saves the need for using electricity to heat the wash and pre wash. It takes 15 minutes to heat it to a temperature that will burn when touching the metal tap body. The washing machine holds 2.5 kettles of water, which contains 2.5 litres giving us 6.25 litres. A larger black plastic coil with a larger bore size could easily double the capacity of warmed / pre heated water entering the solar panel, But I favour adding an additional stainless steel 20 litre pressurised drinks canister to the top of the panel affording a storage sufficient for taking a shower.

During rare severe frost, simply closing the outside stopcock feed and running the tap will partially empty the panel affording an air pocket to allow for ice expansion. But I have to say, we have external plastic and copper pipe that has not frozen for many years and possibly about 4 or 5 times in 21 years.

If I have a problem, a burst pipe will be outside of the home so no major catastrophe will take place and because of my rainwater harvesting system the water would simply be returned to the main storage tank from the guttering. Net loss = a little more soldering perhaps and a little electricity used to pump the water back to the tank.

Considering also the possibility of installing an internal tank, but really like the pressure from either the mains or from the rainwater demand valve and pump.

Think anyone considering this would have to make sure their combi boiler is happy with preheated water as some of the older ones have a thermostatically controlled inflow. Also consider adding an expansion tank, this is a pressurised metal tank, usually fitted with a car tyre valve for pumping air into it. The idea is that as the water heats up the non return valve will prevent the pressure from equalising so that added tank would act the same as an expansion tank in a vehicle by providing a compressible air pocket.

What is an Expansion tank? A tank in a heating system that provides space for the physical expansion of water.
 
How an expansion tank works- Water physically expands when heated and in a closed pressurised system,the extra volume of water has to expand and could easily rupture a closed system. If an expansion tank is not fitted then this water will pass through the pressure relief valve in the combi boiler, which fortunately has not been the case with my system, posibly due to the action of the plastic coil of tubing.

Most expansion tanks have a replaceable diaphragm which the water pushes against, on the other side of the membrane we have pressurised air. This should be set to a pressure below the pressure release valve and above the pump pressure. This can be altered with a normal car foot pump.

Expansion tanks vary, some are inline and others have a saddle / bracket and connector that allows connection straight into plastic plumbing or a compression tee.

Where should I fit it? The expansion tank should be fitted on a tee piece after the water heater and before the first out let i.e. taps or shower.

 What is the pre charge pressure of an expansion tank? The expansion is set to 45 PSI. This can be altered with a foot pump or compressor.

 What size tank should I fit? The expansion is 4% of water heaters capacity. There is only room inside an expansion tank for half the total volume, as it needs room for the compressed air and diaphragm. So the best basis is to fit one that is 10% of the total water heater capacity.

A pressurised tanked system can be seen here: http://www.diydoctor.org.uk/projects/domestic_hot_water_systems.htm

Useful information on thermal expansion of water.
http://www.watts.com/pro/divisions/watersafety_flowcontrol/learnabout/learnabout_thermexpansion.asp

« Last Edit: 13/05/2009 11:50:47 by Andrew K Fletcher »
 

Offline Andrew K Fletcher

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Sorry for cross posting but thinking of those who only find this page.

Instead of cold water feeding the combi boiler, I have hot water feeding into the combi boiler, so it is a direct heating system, fully integrated and functional. The plastic coil of tubing on the felted roof acts as a primary heat source and an expansion tank, when the water heats up, the tubing becomes supple and expands a little to afford the pressure relief. However, going to fit an expansion tank also, again this extra expansion capacity from a freeze, might just prevent a fracture too. Indeed, we have mdp pipe fully exposed to the elements as I have mentioned before and it has never caused any problems, even when frozen, it remains water tight on thawing out.

Your system is ideal also, and you can have antifreeze in the panel rather than water, plus you will have sufficient water to provide your night time usage, so the bigger the tank in your case the better.

Before you fork out for a new tank make several trips to the local recycle / public disposal place. There they have lots of the fully lagged tanks, and if there were any leakage on them it would be fairly obvious. Last time I got one for free with a header tank sitting on top of it and a copper coil already inside. The tanks are very common as more people move to combiboilers throwing out perfectly good tanks

Might eventually go down that route, but for now enjoying the savings and finding the water much hotter than when the combi boiler is used. But would probably still go the direct route with an expansion tank fitted to the outlet. These tanks cost a little more, but from the tip the price will still be next to zero :)

Solar pump is a good move as would prevent the reversed heat transfer when the sun is hidden.

I think you might be in for a shock when you see just how efficient the corrugated sheet is when thermal lagging is applied to the back of the sheet. I am amazed. Also, using 22mm and 15mm copper tubing rather than microbore there is zero problem with lime scale.

The corrugated sheet is the key to this panel as the surface area is greater and the corrugations wrap around the 15mm juxtaposed vertical pipes maximising the heat transfer to the water inside the mat black copper pipes.

This type of stainless keg is ideal:
http://www.jimsbeerkit.co.uk/cornelius.htm

 

Offline Andrew K Fletcher

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Cooling Boiled Water Temperature 98 degrees C


DIY Solar Panel Water Temperature 70 degrees C
Thermometer placed in water from the DIY Thermal Solar Panel On 29 May 2009 at 11:33:43 gmt



Bottom of Form
DIY Solar Panel Water Temperature 75 degrees C taken on: 29 May 2009, at 13:45:01 gmt Outdoor shade temperature: 25.6 degrees C

Water temperature from the DIY Solar Panel measured 75 degrees C at 1.30 pm outside temp in shade was 26.7

Even on a relatively dull day it compliments the combi boiler by reducing the gas consumption. Now have to wait and see how the electricity and gas bills alter compared to previous bills. As I mentioned before saving on electricity by filling washing machine with solar heated water and now installed mixer taps from Ebay for 50 including postage, should have been 345.00 "Don't ya just love Ebay :) "

Also purchased a shower head set complete with stainless rail and chrome plastic fittings at Lidle for 2.00 LOL but the thing about this shower head is it has a water saving device and a setting that introduces air into the spray saving around 25 % of the water and therefore an additional 25% of the gas consumption used to heat the water.

« Last Edit: 29/05/2009 18:50:36 by Andrew K Fletcher »
 

Offline Andrew K Fletcher

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Ultimate test was performed today by my wife and I.

Yes, we both had our first thermal solar panel only shower and we had ample hot water. Now we really start saving money :)

 

Offline Andrew K Fletcher

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Suggested Improvements / modification

Goin to use a 50 metre coil of black mdpe pipe at least 22mil bore, I would then cut a circle of polycarb sheet to increase the heat of the tight coil of black tubing. This will give you additional heat in the winter and prevent freezing. Going to add a circle of corrugated steel sheet thermally insulated under it and painted mat black on the upper side and foam insulated on the bottom. This will increase the amount of pre heated water stored.

May even prove to be a cheaper solar panel for people who can't be bothered to solder copper pipes.

Thought about installing a tank as suggested by others. But the downside of this approach is that many hours of sunlight would be required to heat the water to warm, and this will inevitably be relying on electricity to increase the temperature whereas the direct tank-free system heats up in 15 minutes of direct sunlight after being completely emptied of hot water. Short bursts of 15-60 minutes of sunshine in the UK is about all we can expect as a constant most days, so this system is going to be more productive in providing our instant hot water usage.

Electricity and gas bills are due tomorrow. We have 6 monthly bills and our solar panel has been supplying hot water when the sun shines and even warm water when the sun is hidden behind cloud cover, for 4 months of our half yearly domestic use.   Stay tuned for my next report and a comparison of the previous years bill.
« Last Edit: 26/08/2009 10:40:49 by Andrew K Fletcher »
 

Offline Andrew K Fletcher

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6 Months Gas and Electricity

Last Year Electricity Units Used:   1717

This Year Electricity Units Used:    1509

Units Saved:             208                  Savings =     29.23p


Last Year Gas           Units Used:    83

This Year Gas           Units Used:    73

Units Saved             10           Savings =     14.08p



Total Savings:                          43.31   

Annual Savings based on these savings over 6 months.                     129.93

Cost of DIY Solar Panel, excluding new shower thermostatic taps            116.00

Estimated Annual Profit   May be less or more depending on sunlight             13.93



Savings are from 4 months since installing the Thermal Solar Panel and very poor summer weather with it being rain or overcast on many days. Even so the savings so far speak for themselves.
« Last Edit: 28/08/2009 10:40:15 by Andrew K Fletcher »
 

lyner

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That's very impressive AKF.
The next big step is to incorporate it into your main system. That's what costs the GBP so much that they're not all doing it.
Idiots in government don't seem to know the word SUBSIDY.
 

Offline Andrew K Fletcher

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This is incorporated directly into the hot water system and operates under mains pressure feeding hot water into the combi-boiler inlet. That's the whole point, this system is installed and running for just over a hundred pounds.

Are you refering to running another solar panel into the central heating system? If so that is taken care of with a log burner :) savings from which are in excess of 700 per yesr.
« Last Edit: 29/08/2009 10:38:49 by Andrew K Fletcher »
 

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