The short answer
Measured in the field: +8.9%. Real gain, just not 25%.
Plain English
Datasheet: 'Module power increases 5-25% generally' (JinkoSolar 72HL4-BDV, bifacial factor 80±5%).
Field: NREL trackers in Golden, Colorado, 1.5 m over mowed grass (albedo 26%) made +8.9% more energy, June 2019 to April 2020.
IEA PVPS: single-axis trackers over natural ground generally see bifacial gains under 10%. Snow pushes it up; low and dark pushes it down.
Different measures: the datasheet range is module power, the 8.9% is measured energy. That gap is the point.
Installer tip: compare front-side STC watts, model the back with your site albedo and height, and size cables, fuses and inverter input for the extra current.
Source
IEA PVPS T13-14:2021, Bifacial Photovoltaic Modules and Systems (p. 13 executive summary: <10% on natural ground; Table 29, p. 139: NREL BEST field 8.9%, albedo 26%)iea-pvps.org ↗
JinkoSolar JKM560-580N-72HL4-BDV-F6-EN datasheet (p. 1: 'Module power increases 5-25% generally'; p. 2: bifacial factor 80±5%)www.jinkosolar.com ↗
Where installers ask this
- Is Bifacial Solar Panel claimed wattage meaningful for rooftop mounting? (r/solar)
- reddit.com/r/solar/comments/1ruk094/bifacial_panels_on_rooftops_and_other_issues/
The full answer
What bifacial gain do you actually measure on your sites?
Ask a question →