diy solar

diy solar

Diagnosing Problems with a Photovoltaic System


Works in theory! Practice? That's something else
Sep 20, 2019
Key Largo
You have a solar array on your roof, how do you know it's putting out all the power it can be?

How much energy should I be capturing per day?

Insolation Map
An insolation map gives the average amount of sunlight equivalent at 1000W/m2 per day. So, looking up your number and multiplying by the size of the array will give you a very rough idea.​
Example: Ten 250W panels with an insolation of 5: 10 x 250 x 5 = 12.5 kWh, -20% losses = 10 kWh per day.​
The insolation model is a yearly average number, to get a more precise number for exact number for any day of the year based on your panels orientation, you can use a free modeling tool like NREL's SAM.​

Something is Wrong! How do I diagnose it?
If you haven a system like Enphase or Solar edge, every panel has a meter on it, so you can pretty easily see if any panels are not producing. But what about everything else? If you had your system installed and it's still under warranty you can just call them back out to fix it. If not, here are some things to try.

A lot of times you might just be losing power as there is a dirty film on your panels. In the morning, while the panels are still cool, trying hosing them down. This is the first thing to check/try. See Tips for cleaning your panels
Your system will hopefully be on your roof for 25 years or more. Tree's grow during that time. Track your power over the course of the day, when it's not producing take a look at the panels and see if any are in shade.​
Damaged panels, or panels with wiring problems, often have hot spots or will be warmer that other panels. This can be dectected by a thermal imager and is talked about more in How can I find out which solar panels are damaged?

Solar Panels and wiring can be Dangerous
Do not attempt to test live circuits even in twilight or moonlight unless you know what your're doing and having the proper safety equipment!​
How dangerous is it?​

The problem is your blood is a pretty good conductor, it's your skin that provides the resistance and it can be breached as low as 30V; less if it's humid or you're wet. A string of panels in the U.S. can be up to 600V, even in twilight (possibly moonlight). You don't get power from the panels as the low amps aren't enough to power the inverter, but as you can see from the table above, it doesn't take much current traveling hand to hand to kill you. Amps can kill you, voltage can kill you. Be safe!​

diy solar

diy solar