There are some misleading stories getting around about advantages of one technology over another, these are the most common I keep hearing....

I've heard some panels work well in the shade / are shade tolerant:

• All panels are Photovoltaic devices - meaning they need light to create electricity! Direct irradiation (photons of light energy) striking a panel will produce more energy! Cloud cover is a form of shade (although not as intense as shade from a tree or chimney) - output will be reduced in this instance with all panels. Heavy shading from a large tree is a big problem for all panels. Higher efficiency panels take up a lot less area on a roof - there may be a spot that is less affected.
• An accredited designer is trained to calculate the effects of any shading on your site. I can find the best place to locate the panels to minimise the losses and provide you with accurate output figures you can expect from your system.

I've been told that if a single crystalline cell is shaded the whole panel or even the entire array will stop working:

• Good quality crystalline panels have bypass diodes fitted so a maximum of only 1/3 of a single panel would be affected. even on a small 1kW system this would account for only 5% of the overall surface area.
• Cheaper panels commonly do not have bypass diodes fitted and may suffer more.
• Amorphous panels will lose a smaller percentage of output if covered by the same shade area as crystalline. Amorphous panels are more likely to be in shade due to the dramatically larger roof area requirements (up to 3 times more surface area needed).
• clever marketing sometimes tells you only half the story

What about high temperatures - some lose a lot of efficiency don't they?

• All panels lose some efficiency in high temperatures - some more than others (usually no more than 0.2% per degree above "nominal operating cell temperature". Crystalline panels have a slightly higher de-rating for temperature than amorphous panels.
• Crystalline panels will work better in cooler temperatures (hence the thousands installed in places like Germany). Consider our climate - we have far more days below 30 than those above - temperature is not really a problem!
• Best practice system design accounts for temperature losses so you are quoted net output figures. Many panels have a 'nominal' output at 40-50 degrees Celsius
• A good framing system will allow at least 150mm clearance between the panel and roof for ventilation to help dissipate heat (this also allows for leaf litter to fall through under the panels)