In praise of Khepri, Ra and Atum...

A few words about Solar Power - or in this instance, Solar Water Heating.

We've had a Photovoltaic solar panel for some years now to provide electrical power for the 12v systems on the caravan - its a large 50 watt panel, so produces loads of useful power and drives the numerous 12v systems in our van even on a cloudy day. The concept of "free" energy is a non-starter of course as manufacturing these systems and buying them are quite costly on many levels. However, the photovoltaic panel does give us the freedom to stay at many small caravan sites for long periods of time without having to worry about the battery going 'dead' and leaving us without light and water pumps. We are not keen on sites that have mains electric hook-ups because they tend to attract those with massive vans who spend 90% of their time sat in their vans in front of the telly... Why bother going away?

So with some real-world experience and a lot of background research, I was quite struck on the idea of using some form of solar power to heat or pre-heat the water for our home. I'd been to the Centre for Alternative Technology at Machynlleth in Powys, Wales in the early '90's and had been impressed with much of the stuff I saw - and I vividly remember seeing the amount of hot water they were getting by painting old steel flat-panel radiators matt-black, placing them in a sunny position, and pumping water through them... Hmmm.

The recent BBC TV series "It's Not Easy Being Green", with moustachioed Dick Strawbridge as the driving force, rekindled my interest, particularly with the advancements in solar technologies. I was captivated by the episode where they installed the solar water heaters at Newhouse Farm. I was also well impressed by the water-wheel providing electricity, but that's another story...

During our stint working the Cider & Perry Bar at the Moorgreen Show at Watnall in August '09, I had chance for a break and a wander round the site. During this amble, I came across a stall run by a local company who specialised in sustainable, renewable and solar heating applications, so I picked up a leaflet. Time to do some more research. Fortunately, the rear of our house faces SSW, so gets sunshine from about 9.00am until the sun sets, and the pitch of the roof is quite steep - ideal for a solar collector in these latitudes. The second photo here was taken at about 9.30am in late March. By December 2009, I felt informed enough to go for it, so started getting an idea of costs and quotes.

We decided on a local company called Solar-Heat UK, mainly due to Chris, the boss and technical wizard, being straightforward and open about the job and quote. No sucking in of air through teeth or loads of glossy brochures, nor did he turn up in a flash car and wearing a suit... With clipboard in hand, it only took him 10 minutes to survey the house, airing cupboard and loft. He said the job would be quite simple and it was, all done and dusted in two days. Apart from the solar collector array of evacuated tubes on the roof, the only other obvious signs of the conversion are a larger hot water storage tank and a few extra bits of pipe in the airing cupboard. There is a little bit more in the attic space with additional pumps, a pressure vessel and a small radiator to shed excess heat during hot sunny days.

As mentioned previously, the interesting bit for me is the animated information screen on the control panel; this shows the activity of the two pumps and the temperature displayed from the three sensors in the system: one at the solar collector, one at the top of the hot water storage tank, and one at the bottom of the tank. Over the past fortnight at the end of March 2010, with showers of rain and sleet, cold winds, the odd sunny spell and an ambient outside day-time temperature of 10C to 14C maximum, the hot water boiler hasn't even fired up for four days, the solar collector easily raising the water temperature at the bottom of the tank to 51C... And this is with the cold feed coming into the bottom of the tank at about 10C - 12C! Even on the grim and cloudy days of this early spring, the solar collector has managed to pre-heat the water at the bottom of the tank to between 25C - 30C, so reducing the amount of energy needed by the boiler to heat the water. So looking good so far. I'll be very interested to monitor the meter readings and energy bills though over the long term.    

So would I recommend solar water heating? Definitely, but with some provisos. Financially: If you have an electric shower and don't use the bath much, it will take many years to pay for itself. We have a gravity-fed shower from the hot water tank, so are already reaping the benefits. Some sources quote savings on heating water of only £50 per year; I think this is pessimistic - and is also based on recent fuel prices. If we do only save £50 per year, it could take us over 60 years to recoup our costs - strewth! However, as we currently pay over £700 a year for our energy (so little you cry?), I am convinced that the savings for us will be much more than this. Does anyone believe fuel prices (Gas / Electric) will fall though? From a long-term viewpoint, I think we have made the right choice from both an environmental and financial stance. Better still for those thinking about it, grants for renewable and sustainable energy resources - including solar hot water systems - come on-line in 2011. We decided not to wait...  

Oh and for those who didn't know, Khepri was the ancient Egyptian God of the rising or morning sun and Atum was the ancient Egyptian God of the evening or setting sun. Ra was of course the God of the noon-day sun.