Estimating the learning curve of solar PV balance–of–system for over 20 countries: Implications and policy recommendations

Solar photovoltaic systems installed on homes and commercial building rooftops are deemed central for a low-carbon future. As capital costs of photovoltaics continue to fall, its role towards making buildings more sustainable and environmentally-friendly will continue to grow. Capital costs of a photovoltaic system comprise the module and balance-of-system costs. The latter refers to everything-else needed to make the photovoltaic system functional including cables, mounts, labor, etc. While modules are priced internationally, the balance-of-system cost is country-specific. Price developments of modules, which have been thoroughly studied in literature, followed an 80% learning curve. Research on the balance-of-system learning curve however, has not been as extensive. In this paper, we estimate for the first time the learning curve of balance-of-system costs in photovoltaics for more than 20 countries via an extensive dataset. Our calculations yield a global learning curve for the balance-of-system of 89%, which corresponds to a progress ratio of 11% compared with 20% for modules. Understanding the rate at which capital costs of photovoltaics are falling with such detail will aid in more effective renewable energy policy planning and budgeting. Finally, some steps requiring no financial commitment but can bring down balance-of-system costs are discussed, which greatly contributes to a cleaner and more sustainable future.