Part One: Solar Heating

Something for nothing? Well, not quite but still a very good idea and with increasing competition in the sustainable energy sector prices are falling. Combined with the possibility of a Government grant to sweeten the pill, more and more people are looking to solar heating to reduce their carbon footprint and do their bit to prolong Homo Sapiens’s stay on the planet. As global warming becomes something we have to live with for the moment, there is a growing realisation that we might be able to get a bit back from those scorching summer days.

So why not surprise your husband and install a solar heating system for his next birthday present? But where to begin and what system?

Solar Panels

Generally these go on the roof, but can be mounted on frames on the ground subject to planning regulations. Known as collectors they fall into three groups.

Flat Plate. Basically, an array of typically copper pipes attached to a black metal plate to absorb the Sun’s radiated energy and pass it on to the fluid within the pipes. Because temperatures in January and February still drop below freezing, the fluid used is often anti freeze although some new systems use polymer plate collectors or metal plates with silicon rubber pipes. As these materials are flexible this allows water to be used in the pipes, which, in some countries allow them to be plumbed straight into the existing hot water tank.

Evacuated Tubes. In these panels a grouping of vacuum tubes laid out in parallel absorb the Sun’s radiation. There are two types of vacuum tubes defined by their method of heat transfer. The simplest have a U shaped copper pipe running through the vacuum tube, and water or antifreeze is pumped out to the heat exchanger. A more complex design uses a liquid which vaporises, and needs a transfer bulb .This bulb in turn transfers the heat energy to another liquid, water or antifreeze, and is again pumped away to the heat exchanger. These systems have a higher efficiency factor, and heat the fluid to a higher temperature but are rather fragile and more expensive.

Photovoltaic Cells. These panels convert the Sun’s rays directly into electrical energy, which is then used to heat your hot water in the tank. We have all seen them powering transmitters by the side of the motorways and lighting up our hand held calculators. They avoid all the freezing problems but yes, there is a catch as you knew there would be. They are again expensive and take some years to repay the capital cost at present prices.

Heat Exchangers.

The heat exchanger is just a fancy name for the coil within the hot water cylinder, through which the heated fluid flows. In the U.K. the primary coil as it is known, must be a separate system, and in homes using a gas or oil fired boiler, is a continuous sealed loop of copper pipe running from the combustion chamber in the boiler, up to a coil in the cylinder and then back to the boiler. Because water has a habit of expanding when it is heated, there is a pressure relief valve fitted.

Because the solar system needs its own heat exchanger, when a solar heating is installed in conjunction with an existing system, the cylinder normally has to be replaced by one with the additional solar exchanger.

Solar Pumps.

There are not many hot water systems which don’t need a pump or two in their design and solar power is no exception. Unless the solar panels are situated below the hot water cylinder a pump will be needed to push the solar heated water around the system. These can be solar powered themselves and that will add to the overall efficiency you achieve.

Benefits

So, after you’ve found the most suitable and efficient system, put up with the unspoken duty of making the contractors countless cups of tea, and spent all that money what have you got for it? The short answer is quite a lot.

You can of course expect your heating bills to decline. By how much is the big question? That will depend on the orientation of your solar panels with regard to due South in the Northern Hemisphere, and of course the opposite down under.
Also, the inherent efficiency of the system which you have chosen will impact directly on how much energy you will be saving. With a good system, properly installed savings of 50% have been achieved, but typically 25 to 30% is the norm in Northern Europe. That can mean that it will take 8-10 years to break even, but that is assuming that oil, gas and electricity costs remain at their present levels. With the world’s oil reserves’ topping out the probability is that energy costs will continue along their upward trend line.

That is good news for the home owner with a solar heating system, as it can be seen as a form of hedge against 30% of any future price rises. Should that occur the owner will be laughing all the way to the bank, and the break even point will happen much earlier.

Also, as our summers get hotter the benefits will only increase. Each year we see record temperatures being broken around the world which makes solar heating an increasingly attractive option. And best of all is knowing that we are doing our bit to keep the planet for our children as we knew it.

Part two