The National Renewable Energy Laboratory (NREL) conducted a time-motion study and found that retrofitting roof-integrated PV requires 7% less labor than standard solar installations. For new builds, installation times fall by 44%.
From pv magazine USA
NREL conducted a time-motion study on solar contractors installing roofing-integrated photovoltaics (RIPV) on residential solar projects at several sites in California. The researchers published their findings in “Observations and Lessons Learned From Installing Residential Roofing Integrated Photovoltaics.”
They said that new construction RIPV can be installed very quickly. However, the time required for retrofit RIPV is still comparable to that of standard solar installations. The installation times are still higher for retrofit RIPV, at least in part, due to the application of new techniques and the continued evolution of supply chains.
This analysis was prompted in part by the fact that building-integrated photovoltaics (BIPV) have not kept up with expected price declines. This is despite the fact that investing in BIPV during the retrofitting of roofing, siding or windows can reduce or eliminate the need for separate solar components. Even when these hardware and labor costs are factored in, the expense of BIPV installations still tends to surpass that of conventional installations.
To understand why costs remained higher than anticipated, NREL interviewed industry experts and performed time-motion studies at various RIPV residential installation sites.
The research compared the time taken for RIPV installations with that of standard residential solar installations. In the United States, 32% of the installation costs are attributed to racking and mounting, 32% to electrical work, 20% to meals, breaks, cleanup, and delays, and 16% to travel and installation preparation. Overall, the study found that standard installations required 6.9 worker-hours per kilowatt installed.
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