What affects the performance of the solar system?
Solar irradiation data can be used to calculate nominal solar system performance for every postcode in Australia. Many solar calculators are available on the internet and LG has one here: calculator.
Non-LG solar calculators estimate the output from an optimally installed system with panels facing perfectly north (in the southern hemisphere) at the optimal angle (approximately the angle of latitude less 3 degrees). An average 'standard' solar panel is used for these calculations, but higher quality 'N' type silicon panels such as the LG Neon 2 range have higher output than average due to better performance in low light conditions and higher temperatures. Keep in mind when using solar calculators that most homes in Australia have not been designed and built with perfect roofs that maximise solar output so these figures should be seen as a maximum. Your local LG Authorised Dealer https://www.lgenergy.com.au/dealer will be able to give more accurate solar generation estimates based on your individual roof.
Maximising the total units of solar power generated is generally not the first priority when designing a solar system. The real goal is to maximise financial savings and this is achieved by designing a solar system that generates free power when you need it most. Orientating panels east, north or west affects the time of day when your solar system generates power. East facing panels generate power from first light, peaking in late morning but give very little in the late afternoon. North facing panels peak at about noon but don't give much power early or late. West facing panels are poor in the early morning, peak in the early afternoon and continue to give power until sunset. For example, facing all panels north with maximise generation but if the household uses most power in the mornings and late afternoon facing some panels east and west is optimal as it gives more power at these times and therefore bigger financial savings.
Having said that orientation E, N, W affects the time of day solar peaks, the 'pitch' or angle of the panel from horizontal affects the time of year, winter or summer, when panels are optimised. For example if the angle of latitude is 30-35 degrees (Perth, Adelaide, Canberra & Sydney) panels installed on a 15 degree roof will have a large generation peak in summer because the sun hits the panel almost square-on during these months. Generation in winter will be correspondingly lower. Bear in mind if you intend to heat your house in winter with electricity you might need a bigger system to generate the power you need. In this example steep panel angles of 40 degrees or more help winter generation. Note that due to the longer days in summer and generally clearer skies in most states, summer generation is considerably higher than winter generation. This difference can be quite pronounced with most solar systems giving double the generation in a summers month than a winters month.
Shading is the biggest enemy of solar performance, particularly in winter when the sun is lower in the sky and shadows are longer. If this is an issue for your home a solar system with micro inverters or optimisers is recommended to minimise the impact. Another form of shading is dirt build-up on panels. Pitch angles of 10 degrees or more encourage self-cleaning by the rain.
Individual panel properties have a significant affect on solar system performance and in real world testing there can be up to 10% difference in panel output, even on new installations. The major factors to consider are:
- Temperature Characteristics - Pmax. This is a measure of how much panel performance declines with each degree C over 25C. So for example the LG Neon R has a Pmax of -0.30%/C meaning output drops by 0.3% for every degree C over 25C. So for example comparing two panels with Pmax of -0.3 and -0.4 at a summer panel temperature of 75C there will be performances losses of (75-25) x 0.3 = 15% and (75-25) x 0.4 = 20% respectively. Generally N type silicon panels like the Neon R have better temperature performance than P type panels.
- Low Light Performance. Solar panels are given a nameplate capacity, e.g 380watts based on irradiation of 1000w/m2 (approximately a clear summers day at noon). However, the vast majority of daylight hours do not have such powerful light (maybe 200-800w/M2) and at these lower levels N type silicon panels seem to have a significantly higher performance than cheaper P type silicon panels of supposedly the same capacity.
- Panel Degradation. This is a measure of how much a panels performance deteriorates with age. For example the N type LG Neon R will perform at 90.8% after 25 years, whereas 80% is standard for cheaper P type panels. Consistent with the factors above N type silicon panels tend to out-perform the cheaper P type by a significant margin. Not all panels are equal.
Australia happens to be one of the best countries in the world for solar energy, even south facing panels generate more power in Australia than they do in much of Europe, so don't be dissuaded by a less than perfect roof. With all solar installations bear in mind that quality panels, particularly with N type silicon generate more power in all positions.
Try our solar calculator to estimate how much electricity various size LG solar system could generate in your area.