SDI: Solar Dome Instrument

The lack of reliable data for ground solar irradiance (direct normal and global irradiance) is a major obstacle for the development of adequate policies to promote and take advantage of existing solar technologies. Although the radiation that reaches the outer layers of the atmosphere is well defined and can be easily calculated, the solar irradiance that reaches the ground level where solar collectors (thermal and photovoltaic) operate depends strongly on localized and complex atmospheric conditions. These effects are particularly strong on the Direct Normal Irradiance (DNI). Because cloud cover corresponds to the strongest effect on ground insolation, no statistical method that ignores micro-scale (< 2 km) or mesogamma scale (2–20 km) weather systems can succeed in estimating real-time and/or forecasting solar power availability. In this regard, mass deployment of ground measurement points is often necessary for precise solar irradiance mapping. However, a significant problem of this approach is that the instrumentation necessary for gathering high quality ground data on solar irradiance in general, and DNI in particular is expensive, so deploying it in large scale requires a non-trivial investment. In order to tackle this problem, our work proposes a Solar Dome Instrument (SDI), a novel lowcost solar irradiance measurement device constructed using commercial off-the-shelf components that provides global irradiance (GHI), diffuse irradiance (DHI) and DNI. The SDI hardware and software provides GHI readings with less than 3% NRMSE and DNI readings with less than 7% NRMSE compared to the traditional, more expensive solar irradiance instrumentation such as NIP/PSP solar tracker and MFR7 radiometer, while reducing the sensor acquisition cost at least 20 to 30 times and further reducing maintenance and operational costs.