So you are looking at solar power systems and you want to know which one performs the best
To understand the performance of solar power (photovoltaic) systems you need to look at the panel and inverter specifications.
Inverter Performance
Most people concentrate on solar panel performance and forget about inverter performance. But what’s the use of the solar panels producing lots of electricity if your inverter wastes that precious electicity when converting it into home use.
The maximum inverter efficiency (MIE) measures the maximum amount of direct current that is converted into alternating current (usable for home use) by the inverter under test conditions. Most inverters have a MIE over 94%. The higher the MIE, the more efficient it is. Typically, a transformerless inverter will be 2% more efficient than an inverter with a transformer.
Understanding Panel Specifications
| Panel rating and tolerance | If a panel is rated 170 watts and tolerance is stated as + /-5% say then the panel has been manufactured to produce between 161.5 watts and 178.5 watts. Some panel manufacturers state the minimum wattage and tolerance is then a positive figure – so you are potentially getting more watts for your dollar. |
| What is temperature coefficient of power Pmpp and why is it important? | This shows how much the performance of the solar cell (maximum power output) reduces as the temperature changes from standard testing conditions. This is a negative figure. The smaller the percentage the better it is. Typically the range is -0.38% to -0.52%. We recommend not going over -0.45%. Check out this American article for more information. |
| Panel certification | In Australia, panels are accredited under IEC61730 and one of IEC61215 or IEC61646. These independent tests, to internationally agreed standards, give you the peace of mind and help you compare panel performance of different brands. However tests only provide minimum performance requirements at the time of testing under standard test conditions and do not look at how performance falls over time. |
| Salt mist certification | Salt mist degrades the mechanics and performance of photovoltaic systems. Panels accredited under IEC61701 are designed to be installed in any coastal region and run without interference. Salt mist certification is not obligatory in Australia. |
Because the electrical characteristics of all panels are not the same, you may find that panels with apparently slightly worse percentages can perform equally or better. So if the temperature coefficient of power of one panel was -0.41 and another was -0.44, for example, we recommend looking at other factors before deciding which photovoltaic system to buy.
Performance Is Only One Factor
Remember, performance is only one part of the process in choosing a photovoltaic system. You also need to look at build quality, appropriate design, correct installation and reliable warranties.
