Which Panels Perform Best?
Are you one of the 99% of people that ask “which panels are most efficient”?
If so, then you’re asking the wrong question. Panel efficiency only governs how much area is taken up by a kilowatt of panels, which is really only important when you have a small or shade-constrained roofspace.
What you want to know is “Which system is the most efficient?” System efficiency considers losses in the inverter, wiring, and panel configuration, and it is the system efficiency that governs your annual yield – ie how much your electricity bill is reduced by.The following factors can influence the value of your solar investment:
- Panel Orientation and Inclination. Though an (Australian) PV system should ideally face North, good performance can still occur for orientations between East and North, for pitches of 10degrees to 40 degrees. More information is available on the Clean Energy Council Consumer Guide. SunWiz is an expert in performance assessment, using the best software simulators.
- Panel Shading – Shading kills solar performance. Even a small amount of shading can result in dramatic losses in energy yield. The panels should be unshaded for the peak 4-to-6 hours of each day. Some highly technical papers on shading may interest readers: NREL and University of Geneva. SunWiz can perform detailed shading analysis using the best predictive modelling software.
- Panel and Inverter Temperatures – Both PV panels and Inverters perform worse when hot. Increasing panel ventilation and reducing inverter’s exposure to direct sunlight can result in superior yield, as can using panels with better performance at higher temperatures. The DKA Solar Centre provides some interesting side-by-side comparisons of panels operating at high temperatures in the desert. This data has been analysed by Kyocera for your reference. The California Energy Commission has some interesting findings about panel performance at typical conditions (rather than laboratory conditions).
- Panel degradation – over time, the performance from a PV panel reduces. This performance degradation affects some panels more than others, meaning some panels are producing much more than their warranted output after 20 years. Some references: NREL, Sandia Labs, NREL again.
- Panel, inverter, and balance of system quality – although quality is difficult to see with the naked eye, quality can affect performance. This may be due to some in-built features that improve energy yields, or because of longer panel life that produces far greater revenue for you.
- Product and performance warranties matter, but so does being around to service them. Financial sustainability of your panel manufacturer and PV retailer matter. Trina Solar present some interesting information on solar company viability.
- Potential Induced Degradation (PID) has recently reared its head. In tropical regions, panel performance can decline dramatically for larger systems when high string voltages are used. It’s not really a problem outside the tropics, but the Fraunhofer Institute presents some interesting information on PID effects. For PID robustness, Q-Cells comes out on top.
SunWiz takes all these factors into account when assessing the best financial outcomes for its clients.