Motorhome Solar Power.

Solar Panels are typically either made from Mono-Crystalline Silicon or Poly-Crystalline Silicon. 

Mono-Crystalline panels are smaller than the equivalent Poly Panel for the same output but the output current is still similar.  

The greater efficiency of a 100w Mono panel means it uses a smaller area to produce the same power as a 100w Poly panel.

For example a 100w mono panel will be, roughly, about 1,100mm x 650mm whereas a 100w Poly panel will be about 1,200 x 800mm. Both produce around 5amps of power in bright light and cool conditions.

Mono panels are often slightly dearer.

So if space is not an issue you may save by adopting a Poly panel. Note that some Solar Panels advertised as Mono are sometimes Poly, check the physical size is equivalent to a similar output Mono panel.

Note that a Solar panel is more efficient at lower temperatures so ideally you should provide an air gap below the panel for cooling. 

One of the reasons why semi-flexible panels are disapointing performers in bright sunny conditions is the heat build-up due to a lack of air space below the panel as these flexible panels are normal bonded directly to the roof.

In addition flexible panels use a less transparent plastic for the top, not Glass as obviously Glass doesn't bend, resulting not only in a less efficient panel with lower light transmission, but faster degradation as the light transmission is blocked as the panel is used. You may have seen how Car Plastic headlights discolour with time?

Shade on a Solar Panel

When a small part of a Solar Panel goes into shade, those cells stop generating Electricity and instead draw it from the surrounding cells, in effect becoming a heater element. The amount of power drawn is often directly proportional to the quality of the panel. It only requires a small shadow over just 5% of the Panel to drop Power output by 40%.  

This webpage information, supplied by Plwsm2000 from the MMM Out And About Live Forum, answers a whole host of Solar Panel questions :

See this chart below that shows how the power generating capability of a Solar Panel varies significantly between the South coast of Cornwall and the North coast of Scotland -

Above you will find the average KWhours of electricity generated in the UK with 8 x 125W panels. 

You will note that there is a 30% difference in the generation of Solar power between NE Scotland and South Cornwall.

As a comparison a 100w panel that might output 5amps in Cornwall will probably only produce 3.7 amps for more of the day in Scotland. 

You therefore need to adjust your array size according to where you plan to use it. We would suggest a minimum 220w array North of Newcastle. If you plan to holiday South of Le Mans then the high sun and long days might mean 100w is adequate for all your needs.

Click HERE for our page on Solar Power containing a Hints and Tips guide to installing Solar.


This is an excellent article on the different technologies :

Early Blue Sky Solar Charger here :