Rooftop bifacial panels (with reflective background) vs. Monofacial

Screwdriva

Thought I'd share some real world data from my own roof and my immediate neighbour's roofs.

These are 4 X LG 400W bifacial panels, originally installed in 2019 and recently repositioned in a row on our ENE aspect.

Average generation across the last month was 59KWh. Note how the panel (1.3.8), with one side unrestricted towards SSE, notably outperforms (61 vs 57 KWh) the panel (1.3.9) on the North side by 7%, highlighting just how variable albedo gains can be (No such variance below)

I compared this to my immediate neighbour's Hyundai 400W monofacial panels, installed in 2022 on the exact same roof's ENE aspect. (We own two semi detached properties and share a the same roof structure).

Average generation across the last month was 52KWh.

That is a ~13.5% increase in generation on the same roof, same aspect, same slope with the same 400W panel wattage.

Just to confirm these findings, I asked a neighbour who lives directly opposite the road from us for their readings. Average generation across the last month was 51KWh.

That is a ~15.5% increase in generation on a similar roof, facing the same ENE aspect with the same Hyundai 400W panel wattage. I have not measured the slope of their roof but it is believed to be the same.

The usual disclaimers apply: these aren't lab conditions and the panels vary by manufacturer and efficiency (the LG panels are a generation older). That said, having SolarEdge optimizers on each of the above roofs does yield valuable insights. I plan to share a full year's data when I have it.