Genre: Instruction

When it comes to choosing a solar panel , electricians may base their decision on nominal efficiency factors or the price per Watt peak . These are of course two important criteria – but , from a long-term perspective , simply not enough . After all , solar installations must last for 25 years . And they will , provided they are installed correctly and are of good quality . But how do you actually recognise good quality in a solar panel ? For Conergy Australia general manager David McCallum , such panels must fulfil three criteria : they must be high-yield , solid and safe . Efficiency delivers high-yield The solar cells themselves are responsible for the yield factor . Innovative cell designs can deliver efficiencies of 16 % to 23 % , depending on material and processing effort . The market is currently dominated by cells with two metallic collector contacts on the upper side – ' busbars ' . Some manufacturers print three busbars instead of two onto their solar panels to allow for more efficient dissipation of the generated power . David says there are definite benefits in improved power distribution . " Three busbars help to reduce contact resistance between the cells . The result is increased and more consistent module efficiency . " He also believes that combined with suitable cell connectors , the use of three busbars provides more reliability in terms of power generation . David and his colleagues also favour bypass diodes when it comes to module manufacturing . " They function like a protection switch for the cells . If , for example , foliage should shade individual cells , the bypass diodes will channel away power , thus protecting the shaded cells , " he explains . " Once sunlight is no longer impeded , the bypass diodes switch back to their original mode , and the module will once again work at full capacity . " High-quality components provide stability Even the highest yield is of little use if the module does n't last for its projected 25-year lifespan . The production process must lead the way into the right direction . Premium quality components , like specialist solar glass and a robust frame , provide the necessary protection for the fragile cells . But even for solar glass , the choice is endless : smooth , unstructured , micro-structured , heavily structured or even specially coated glass is on offer . Each and every glass type is designed to conduct as much sunlight as possible into the solar module . " Heavily structured glass types tend to attract contaminants , which over time will lead to a decrease in the module's capacity , " David explains . " The module frame stabilises the solar module , and protects both the glass and the cells . The most robust frames are those made from anodised aluminium . They are much more scratch-resistant than coated frames . " David also warns about possible hazards due to hollow enclosures . " Frames should not have any hollow enclosures , as these could collect water , which can then turn to ice in the winter in Australia's cooler climates . As a result , the frame could buckle or even burst . " In summer , contaminants like pollen or dust will find no adhesion , which means that moss growth can be avoided . Contaminants of that type can be particularly critical , as they will permanently shade cells , which will result in a significant loss in module capacity – and in consequence in output of the entire solar installation . The safety aspect is one of the most important criteria to bear in mind when shopping around for solar modules . David therefore advises electricians to pay particularly close attention to the junction box . Faulty construction or poor workmanship can , under certain circumstances , create a fire hazard for the entire solar plant . " I generally advise against clamp , plug or screw connections . These could easily come undone or corrode if installed improperly . The resulting arc could cause the junction box to catch fire . " Instead , he recommends molded junction boxes made from non-flammable plastic with soldered connections . These are moisture-protected and vacuum-sealed , providing maximum safety . Solar module manufacturers offer many safety options : warranties , certifications and positive capacity tolerances . The actual scope of services provided is determined individually by each manufacturer . A warranty period of five years for solar modules should be the absolute minimum offered . " If the solar modules will be deployed in regions with severe weather conditions , electricians should look for additional certifications , like ammonia resistance , or for special certifications regarding corrosion-resistance if the solar modules will be installed in coastal regions . "