Location: Denver, Colorado USA
System Size: 6kW
Modules: 26 REC 230PE modules
Inverter: 1 SMA Sunny Boy SB5000US
A side-by-side comparison of a residential PV system with
Tigo Energy dc optimizers showed an average increase in
energy production of nearly 10%. Detailed analysis of the
results proves that the boost in performance is due to
balancing a string that is split across two orientations.
For a period of 10 days in February this system was operated without DC optimizers. The daily energy production was logged and tabulated together with the daily energy from other PV systems located in the same neighborhood. This information was used to establish the baseline performance of the system under test, and to validate the correlation of the neighboring systems. Another 10 days of energy production was recorded with optimization. The average production with optimization was compared to the average production without optimization to determine the change in performance that may be attributed to the optimizers.
The Results—9.8% Energy Increase
For each period of the test, the ratio of the system under test was calculated relative to the average of the neighboring systems. Without optimization, the ratio
between the systems was 0.8. Enabling the optimizers changed the ratio to 0.878—a boost of 9.8% due to the optimizers.
Figures 2 and 3 both show the array at 3 p.m. on a clear day, so any difference is entirely due to the optimizers. In Figure 2, without optimization, the two strings are clearly evident. The 7 modules in the southeast array are receiving less direct irradiance due to the position of the sun, but the other modules in the string—four in the lower left corner and two others in the main array—show reduced power output due to the string mismatch. Figure 3 shows a very different picture when the optimizers are enabled. The southeast array still shows reduced power, of course, but the other modules in the string have been restored to full power. Their output matches that of the modules in the same orientation, regardless of what string they are in.
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