As a solar system owner, you may have noticed differences between the energy readings displayed in your monitoring app and those shown on your utility bill. In this article, we’ll explore the key differences between these two numbers and shed light on why these differences occur.
It is important to note that the number we are looking for is the number of kWh produced. A kWh (kilowatt-hour) is a measure of energy that is used to calculate your electric bill (residential customers are billed for the number of kWh they consume monthly) as well as measure your system’s performance. The difference between a kW and kWh can be found here. Since your electric bill is given monthly, your electric bill will show the number of kWh pushed to the grid for that month (the label varies by utility but could be called: Energy – Reverse kWh, Banked KWH Credit, Generation kWh, etc). However, the amount will always be different than the number of kWh produced that is shown in your monitoring app.
The reason these two numbers are different is because only net excess generation (i.e. the unused production your solar system pushed back out to the grid) will be shown on your bill. In your monitoring app; however, total production is shown, regardless of where it goes. Consider the image below:
After the solar system generates the electricity, it is immediately read by the system’s components (this varies by manufacturer and solar system type). This information is then sent to your app, which is why the readings displayed in the app are always more accurate (in terms of production) than the utility bill. Next, the electricity your system generates is then consumed inside your home by power appliances, lights, electronics, etc. Any excess power, if any, is then sent out to the grid (this is what is measured by your meter).
We hope this helps clear things up! Personally, we recommend using your monitoring app, as this shows information in real-time and gives more accurate and complete data about the system’s performance. If you are an Energy Select customer, you have access to your personalized myEnergy portal, which shows key information about your system, including production, that can help keep track of your system’s efficiency and performance.