According to new figures from GTM Research, the TPO model, which often promises no upfront costs and is employed most prominently by SolarCity, will peak this year at 68% of the overall residential market. That compares to just 42% in 2011.

But starting next year, the TPO model’s share will begin falling – sliding to 63% in 2018, GTM predicts.

Taking up the slack will be outright loans for PV systems, as opposed to the leases and power-purchase agreements typical within the TPO model.