According to SEIA, over the next 5 years, total installed solar capacity in the U.S. will more than double, with cumulative deployment topping 100 GW by 2021. With these numbers, the U.S. is no longer a newbie when it comes to solar. As the number of new installations continues to increase, what happens to these existing solar plants and those reaching the end of life? Can a case be made for the solar plant monitoring retrofit?

First-generation solar plants were often installed without a proper solar plant monitoring system in place. O&M wasn’t even a topic during the first few years of solar. That means that plant owners may be losing money with under-performing plants, and not even know it. According to a recent article by Wood Mackenzie, global solar installations nearing inverter end of life will reach 21GW by the end of 2019 and will represent more than 14% of the total cumulative capacity over the following five years.

Is the cost of a solar plant monitoring retrofit worth it for the plant owner?

Errors in solar plant performance can mean that the plant is not producing as much power as possible. The number of factors affecting the amount of power being produced increases as the plant ages. Some factors include environmental conditions, aging components, and dirt and soiling. This loss of produced power can translate into a significant financial loss if the performance errors are not detected and resolved quickly.

In the following example, the inverter failed on a 5.4kW residential solar array and the failure went undetected for 20 days. If we apply the electricity cost to the power loss, we can conclude that the homeowner lost a total of $92.80 in just those 20 days. If a professional monitoring system was used, the failure would have been detected immediately.

  • 5.4 kW, 1 Inverter
  • Complete inverter failure left undetected for 20 Days
  • Total power loss, 580 kWh
  • Electricity cost, $0.16/kWh
  • Total financial loss, $92.80

Can installers make money on solar plant monitoring retrofits?

Retrofitting existing plants with monitoring often means a truck-roll and associated costs for the installers. The idea of adding services is great, but can installers make money that way? If they have low-cost hardware combined with the right software tools, they can. Plus, plant owners will make more money through properly performing plants, so everyone wins.
Using Solar-Log’s low-cost option for monitoring residential plants, let’s break this down into actual cost for retrofitting monitoring on a 5kW plant:

  • Truck Roll $175 + Hardware $114 = $289 one-time cost
  • Solar-Log WEB Enerest™ L Software = $20 annually




At $2.99/W, the solar plant in our example cost the plant owner roughly $16,000. If a dip in production can cost the plant owner $92 in just 20 days, adding professional monitoring is a no-brainer for the plant owner and an easy sell for the installer.