The Sun Has Won Research Note: Discerning Trends in PV Installation Data
Summary: Estimating future annual photovoltaic (PV) installations is critical for planning the buildout and operation of energy systems at scales ranging from individual homes, to cities, to nation states, to continents. Yet annual installation rates continue to grow so fast that reality makes a regular habit of surpassing even near-term forecasts, frequently in just one quarter. Linear models of PV installation are ahistorical, have been poor predictors of future deployment rates, and consequently mislead in regards to capital investment, labor requirements, and emissions reductions. The forecasting challenge is compounded by temporal and geographical variability. There are at least three different historical price eras for PV, with different market dynamics, and there are today at least four distinct PV markets, with installation rates determined by contrasting local policy priorities. Due to this variability, different models of future market installation that are consistent with historical installation data can produce final installation totals, and maximum installation rates, that span more than an order of magnitude; existing data are consistent with a 2050 installation total of 25–100 TW, and a maximum installation rate of 600 GW to 6 TW per year. In other words, we cannot distinguish between a wide range of outcomes given existing data. Nevertheless, the exercise of comparing models to the historical record can help delineate and constrain the range of our ignorance, which provides a basis for evaluating scenarios for PV installation over the next three decades.