When you consider all of the different factors that go into the efficiency and output of a solar system, it starts to get really confusing to understand what you are paying for. If you install a 10kW system, how many kilowatt-hours do you get? That’s what you really want to know, right? How does that unit of measure relate to the unit of measure I see on my power bill?
Well, unfortunately, those numbers aren’t as easily available. It really is a privilege to be able to see the output of a solar installation. Yeah, you always hear the estimates, but when do you get to see the back-up. Pretty much never, right? That is why the unique access we have been granted is such a valuable tool, and we are grateful for it. So, let us explain what kind of information we have at our finger tips.
The picture above shows a layout of the home (although not in the proper orientation) and the panels on it. The side with five panels is actually facing south. The sun actually moves depending on what time of day it is, so the graphic doesn’t properly represent where the sun is with respect to the house, but the important part is not the display.
The picture is hard to see, so open this link in a new window so that you can switch back and forth as you read.
The numbers that you see on the panels are the number of watts that the panel is generating at the current time. The picture you see was from March 12, 2014 at about 12:30. Just by looking at this, you can see that the south facing panels put out more wattage. As the day moves on, the panels in the west will begin to generate more than the ones facing east, but the south ones will be higher wattages relative to the east or west facing ones no matter the time of day.
The two little boxes on the upper left represent the two inverters. There are two of them because they have a maximum wattage of 5kW that they can convert. So, 20 of the panels go through each inverter to convert DC power to AC power. The numbers on them represent how many kiloWatts are being produced at the current time. It is obvious to see which one is connected to mainly the panels on the west.
Now, this data can be determined for any time, every single minute, from the very date of the installation. Using this information, you can determine where the clouds were, at what time, of any given day. You can break down the efficiency of the west facing panels, versus the east facing panels, versus the south facing panels. One interesting find was that on cloudy days, the south facing panels weren’t more efficient. The reason is because the clouds can diffuse and reflect rays, thus taking away the advantage that the south facing panels gain.
Unfortunately we can't share those details with you without making a direct link to the data, which we are not allowed to do. But make no mistake about it, the amount of information that can be derived from this data is very vast. Make sure to check out our periodic breakdowns of the different interesting findings. Until then, feel free to check out the data that we currently have available.