You’ve read the compelling arguments, seen the numbers and talked to the experts. It’s conclusive that solar panels are a smart move. But once the installers have left, how do you really know just how well your new panels are performing? How do you know if those numbers really add up to what you’ve been promised?

Take, for example, someone who’s just had their new 5kW system installed a couple of weeks ago. Everything seems to be going smoothly, until they get a reading of only 4kW of peak power for one day. What happened to the promised 5kW?
One factor is that most Australian solar systems will usually peak at 80% of their specified power peak. But before you get on the phone to complain, this isn’t uncommon in a number of industries. Your car’s advertised fuel efficiency is going to be an average, not an everyday reality.

For solar panels, you have to take into account something called system losses.

Temperature loss is a big one, which can actually account for almost 10% lower performance than advertised. When solar panels are too hot (ironic, considering their job is to be in the sun), they can actually lose some of their rated power. And we’re not necessarily talking about those awful 40 degree days that we get in a heatwave. Even a sunny 25 can be enough, wiht performance declining the hotter it gets.

Manufacturer’s power tolerance can contribute to around a percent of your total system loss. Dirt is another common culprit, blocking the sunlight from reaching the solar cells and ultimately reducing your power output. This can cost you anywhere rom 5–15% of your power.

Then you’ve got voltage drops due to electrical resistance in each wire that your electricity flows through, so that knocks off another 2%. And finally, take a look at your inverter. IF this isn’t as efficient as it could be, then your system won’t be either. After all, everything goes through your inverter, so it calls the shots when it comes to performance.

So what can you do to make the most of the panels you’ve got? Keep them clean, invest in a modern, efficient inverter if you haven’t already, and keep temperature in mind. You might not see 5kW of power being generated, but with good maintenance, your panels will serve you well for decades.