Solar System Monitoring Offers More Than Personal Gratification

Not only can monitoring ensure that your solar photovoltaics are performing as expected, it can help identify problems—such as blown fuses—at the time they occur as opposed to days or weeks down the road, after the efficiency loss has prolonged your return on investment (ROI).

“If you’re not at full operation, you’re losing money on a daily basis,” Richard Duong, Moxa Americas' business development manager for renewable and smart energy, said in an online discussion. Full operation could be hindered by a line shortage, or something as simple as dirty panels. System monitoring, in essence, can indicate reliability. Duong believes that reliability is the key to determining whether your installer and equipment provider is delivering on the agreed contract, knowing when to call for support, and calculating when your system will meet its ROI target.

The introduction of the microinverter by Enphase in 2008 allows each solar PV panel to be monitored individually, through the placement of a mini inverter behind each panel. Microinverters have also helped increase system reliability, as this relatively-new technology can make adjustments to optimize each solar panel’s energy performance.

“Big-box inverters have to optimize for the weakest link in the chain, so if one panel is shaded, then the whole array would go down between 30 and 50, or even more percent,” said Ken Oatman of Astralux. “With the microinverter you don’t have that problem. If one panel is shaded, that’s the only one in the whole array that goes down—even a leaf can reduce the power for a large array.”

In terms of distributed generation (DG), where smaller-sized solar plants power a given area, Duong has noticed an increased interest in system monitoring from multiple parties. Besides manufacturers and service providers, investors who provide the money to put these DG systems are exhibiting more interest in system performance. “You have to prove the system can stay online long enough; that components aren’t going to fail and impact ROI. Investors are more interested in this—but [they] want the transparency,” Duong said. “If your array is not going to meet its ROI targets it might be a failure, and the bank doesn’t want to repossess those assets.”

Whether you have a residential or commercial solar PV system, panel expectancy is the same—about 25 years. Most inverters only come with an eight to 10 year warranty, so you can anticipate that the inverter will eventually fail and your system will stop producing clean energy. Instead of noticing a decrease in energy production on your utility bill a month later, monitoring can uncover suspicious activity sooner and make you more aware of your energy use. This tends to encourage more conscious energy use, which results in less carbon emissions that need to be offset in the first place.

The best method of monitoring a solar system’s reliability will differ for everyone. Duong advises that system owners or leasers calculate the amount of power they need to produce on a daily basis to meet their ROI goals, and then check the production report regularly.

“When the numbers have been down a few days, may be correlated with weather or the system being down,” Duong said. “Consecutive days of not meeting the average expected power—that’s a point of concern that you need to look into the details of your system.” 

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