We have 12 solar panels in our array.  On a good day they produce around 400w of power  (the maximum design output is 660w).  This is about enough to run a small electric drill or a food processor or 6 ordinary light bulbs.

The panels are Shell SM55's and are rated at a nominal 12v each.  We have pairs of them wired in series with the pairs in parallel.

We thought long and hard about spending a lot of money on these solar panels.  We had to ask questions like “Does the sun ever shine enough to justify the expense”?  After much thought we decided that on average it does.

One also has to balance the relatively high initial cost against the minimal maintenance costs.  Unless they suffer mechanical damage they are guaranteed absolutely for 10 years and Shell expect them to be producing in excess of 80% of their design wattage in 20 years time.  They are a long term investment.

The tracker was made by us and uses parts of a satellite tracker we found at the dump as well as a 24v truck windscreen wiper motor.  It is not designed to exactly follow the sun but to point approximately in the right direction.  It does this by moving a few degrees every hour and returning to the start point at night.  It rotates on what’s left of a Landrover back axel.

The rate of charge and maximum voltage is controlled by a Trace C35 charge controller.  This lives in the grey box attached to the axel.  If you have a small battery set and a large array it is possible to damage the batteries by overcharging.  The C35 senses the voltage and does not allow it to rise too high.

The power from the panels travels down the wires you can see on their right.  As this is a low voltage/high current there is no chance of you being shocked by them but sparks would fly if the two wires touched.  

When large currents are transmitted over longer distances it is important to keep the diameter of the conductors as large as possible.  We use ESB neutral cable obtained as scrap.  It has aluminium conductors wound around a steel core.

Like all our alternative generating equipment the output is fed into our batteries where it is stored for future use.