Are you all pleased with your solar panels for hot water heating

championc wrote: »

I personally am trying to see if it's worth my while for this transfer to happen in the opposite direction - transferring surplus heat from the cylinder back into the radiator circuit. It's a larger scale version of heat dumping.

Anybody done this ?


C

One interesting way to deal with surplus summer/autumn heat would be to incorporate a seasonal thermal store, - basically an extremely well insulated and large thermal mass. Might be difficult to incorporate into an existing house, but if might work in some scenarios.

Wikipedia link to 'Seasonal Thermal Stores'.

championc wrote: »

I personally am trying to see if it's worth my while for this transfer to happen in the opposite direction - transferring surplus heat from the cylinder back into the radiator circuit. It's a larger scale version of heat dumping.

Anybody done this ?


C

In one system we were working on in the past I seen this happen by accident,
What happened was in mid summer the cylinder got to very high temperatures of around 90 degrees c, The solid fuel stat was probably located a little too close to the cylinder and the temperature traveled down the solid fuel pipe off the solid fuel coil in the cylinder, it then knocked off the solid fuel pump and took a good bit of heat out of the cylinder to the radiators, but they would of went just luke warm and reduced the temperature of the cylinder from 90 c to about 55 c. It was a 300 l cylinder.

but even without this if lets say this time of year you start putting on your heating and it has been a very sunny day outside, it is possible that your cylinder can be up at 80 or 90 degrees and the heating system could be running at 70 degrees so what happens is opposite transfer through the heating coil only a small bit albeit

championc wrote: »

I know this is a very vague question but hopefully someone can give me a less vague answer - If my store was at 75 and I turned on my rads pump (without the boiler) to allow for the store heat to transfer into the rads circuit, how long would you expect before I would begin to feel some heat from rads - 10 mins, an hour ........

My thought would be to put a temperature controlled valve in place to basically allow the store to dump heat once the store temp was over 55 deg.

Or maybe a simpler proposition, In a typical setup that has a rad as a heat dump, how quickly does a rad like this heat up and how long would a store at 75 take to be reduced down to 55 (basically allowing for the use of the store hot water that night or the next morning)


C

I think in my last example i give which would have been something like what you want to do, it took about 10 to 20 minutes to start feeling the radiators heat, but like i said it was only to a slight luke warm of all the rads, if you were doing this to try heat the house I personally cant see it really doing much, it might be of more use as something that would kick in maybe 20 minutes before the heating comes on, to save a little on the heating fuel costs.
But this is just an opinion - I could very well be wrong, i've never actually tried fitting a solar system to heat radiators, just to heat DHW

gjc wrote: »

Also what is the best way of comparing different products.

Comparing different solar panels is not a particularly easy task (in my experience at least ).

Decent panels should be certified and appear in the Solar Keymark database. It's easiest if you are comparing two panels which are both certified by the same certification body such as DIN the German certification body.

You will need get the licence number for the panels you are looking for from your supplier, hopefully it will be on their literature or website and then get the test data sheet for that panel from the data base. The licence number will look something like this: 011-7S206 R

You should then be able to compare the performance of the panels under test conditions for a location in Germany.

Whilst the output you get in Ireland won't be the same as for the test location it does at least give you a chance to make a comparison between panels and relating that back to the price you are being quoted for installation you can see which is giving you the most bang for buck.

It's also helpful to look at the stagnation temperature of the panels which is given on the test data sheets the higher the temp. the better.

The whole process is not very user friendly and can be pretty baffling but it's the best I can offer you.

gjc wrote: »

Excuse me I am thinking of getting solar panels to heat water only looking at 300l tank evacuated tube system...trying to sift through info .....can I ask what temperature is the water heating up to at this time of year?? Also what is the best way of comparing different products. Any help would be grateful.

PM sent
Cc

gjc wrote: »

Excuse me I am thinking of getting solar panels to heat water only looking at 300l tank evacuated tube system...trying to sift through info .....can I ask what temperature is the water heating up to at this time of year?? Also what is the best way of comparing different products. Any help would be grateful.

Hi gjc,
I've sent a PM to you about a free design service you can avail of which compares the output of different solar panel systems. Using the details of your particular site you can find out how much energy different systems will produce and figure out the cost/benefit.


Thanks!

S.

While my pump is in the attic, when up there, I can hear it whirling away but it's just a quiet whirling, nothing more


C

gjc wrote: »

Solar panels installed this weekend question one..... is the system a silent system or do people get noise when the pump is running. my system is not noisy but certainly is not silent (small level of noise) when the pump is running is this normal?? Ta

The pumps usually make a small swishing sound but it shouldn't be very loud at all, but sometimes slight air bubbles in the system can make them a lot louder, this will usually settle down after a while but then there are pumps that do seem to make a lot more noise than normal.

Qualitymark wrote: »

Does it save you money on water heating even with the electric pump?

I tried working out the cost of running a pump on the system for a year and by my estimations it worked out less than 20 euros a year. This was taking into account the amount of time they would usually be running on average every day in a year and the power of the pump which is usually set at about 50 watts or less. So from those figures I worked out how many kilowatts was used on an average year and multiplied it by the cost of a KW of electricity.

Qualitymark wrote: »

And firemansam, do you get hot water all year round?

well its not going to provide you with 100 percent of your hot water needs in the winter months but most decent systems should provide between 60 - 70 percent of your hot water needs for a year, as well as having a little knock on effect of sometimes helping your heating system get up to heat a bit faster.

Thanks for that feedback regarding noise of pump, the pump was only giving out a slight whirling noise there was indeed small amount of air in system which we have got rid of now...pump very quiet now...happy!!!

My 400l tank is sitting at 68deg C after todays sun. Thats top of the tank, the bottom is 42deg.

Yep 2 kids and a dog use a bit of water especially in hot weather like this.
It would have been a lot higher if it wasn't being used all day, I usually change the dishwasher feed over to HW this time of the year as well.
The washing machine has hot and cold feeds so it uses what it need from each.
Best to use it while its there.:)