A prominent UK builders merchant installed solar PV over several of its depots and buildings, totalling 512kWp of capacity. However, the installed systems failed to live up to their predicted output, leaving the system owner searching for answers.

Dorset-based solar installer, Empower Energy, was awarded a maintenance contract to help boost the systems’ output.

The company’s initial inspection revealed a number of issues that were completely unknown to the system owner which were causing significant financial loss. Problems discovered included a module that was broken during the original installation that was never identified – creating unbalanced strings which resulted in energy losses for more than two years.

As a pilot project, Empower Energy recommended retrofitting a total of 67.6kWp with power optimisers and inverters. Malcolm Davidge, technical director at Empower Energy explained: “We recommended to retrofit this project with SolarEdge power optimisers and inverters because we knew that it would significantly increase the system’s energy production. The SolarEdge monitoring system provides us with real-time data so we can immediately detect and address any issues. This not only improves the system owner’s financials, but it means that our O&M services are more effective and efficient.”  

The module-level electronics delivered an increased energy yield and allowed Empower Energy to lay the strings out in a symmetrical pattern on the roof, simplifying the design process and allowing the company to install more modules on the roof. When one of the sites was initially installed using a traditional string inverter there was a need for 54 strings of 15 modules. Using power optimisers and inverters, Empower Energy was able to design the same site with only 18 strings of 40 modules. Another site had six strings of 21 modules with a traditional inverter, but during the retrofit the string count was reduced to four with a total of 32 modules per string. The decrease in the number of strings results in a significant reduction in DC balance of system (BoS) costs. For one of the new sites, a 209kWp installation, Empower Energy estimates a 50% BoS savings.

As a result of the successful pilot project, the system owner is now retrofitting the entire 512kWp portfolio with module-level electronics. In addition, the system owner has committed to expanded its portfolio with a further six sites worth of 861kWp in the pipeline.