Wednesday, 28 March 2012

Solar Power and Immersions.

Could I draw your attention to a very interesting post from Pete on the "Guest Post" page? He has been far more successful than I've been in diverting excess "Free" electricity to his immersion heater.Link to my previous posts on this subject.

Hopefully, once he has more data and the financial justifications we may all be following his path. He calls himself an "Anorak". I think he is on to something which will make everybody with PV panels sit-up and take notice.

Well done Pete....



  1. There is a lot on this topic and on Parson's Switches at this forum:

    Personally I plan to wait until the weather is reliably bright for longish periods and can generate at least 2.5 kW for two hours midday, then I shall switch off the gas boiler ansd wsitch on the immersion. I have been getting six hours continuous PV generation at more than 2kWh in the last week but that's because of unseasonably good weather this last week or so.

  2. More on this issue also at:
    where they found the average saving from roof water heating systems is only about £50 a year!

    What is the true cost for domestic hot water? How much do we really use?
    Let me run through a few points, washing machine:coldfill, dishwasher:coldfill, if you have an electric shower again coldfill. So that leaves baths (if you have one) kitchen sink and handbasins.
    If your hot water cylinder is well insulated, only small losses there anyway. So in real terms, domestic hot water is only maybe 5% of your total heating cost, so don't invest too much time and expense to save £40-£50 per year. There are much better ways to invest in Green energy, and better ways to make savings too. IMO!
    Will it add much to a heatstore, as in this case, well, I believe there are better ways.

    1. Very valid point raised by Chrisso.
      The economics of this depend very much on individual circumstances. I am focused on trying to get the largest benefit possible from my "free" electric and may not be looking at the wider picture. If like Pete you have young children who are using bath water then it becomes a very valuable asset.

      Could you justify the cost of generating hot water?

  3. Someone on the radio today was talking in glowing terms of using solar panel power to charge an electric car. It was unclear whether he is actually doing so or has just had the idea. However a snag might be if you wished to actually drive your car in the day when there's daylight, rather than have it charging at home. The future may well be solar though, and fitting solar panelled roofs and bonnets on cars might be one way ahead...

  4. As I said from the outset, my experience is an experiment both in terms of trying to utilize the energy produced by through panels and to help with the bills. To date we have noticed that our water is hotter and we no longer have our boiler running in the morning for our shower.

    Only time will tell regarding the economics. However, I would be more than happy with the £50 suggested. That will give me a payback in less than 4 years.

    For me however its not just the money. I'm having fun playing and trying to get my energy use down as much as I can. Given the way that my system has performed over the last few days I am pretty confident that there will be extended periods in the summer months when my boiler will be doing very little work at all.

    I appreciate that this system will not suit everyone. However, sometimes he who dares......

  5. Pete said "Given the way that my system has performed over the last few days I am pretty confident that there will be extended periods in the summer months when my boiler will be doing very little work at all..."
    I do agree with that. Usually in the summer we just have the gas heating the water for an hour at the start and at the end of the day. We are planning to turn it off in the summer and have the immersion on at midday for 2 hours on the good daylight days. If it's a poor daylight day then in the evening we can always switch the gas boiler on for an hour.