Temporal Resolution of Input Weather Data Strongly Affects an Off-Grid PV System Layout and Reliability

Abstract

Renewable energy systems design using average year weather data is a standard approach that works well for grid-tied systems, but for stand-alone ones, it leads to dramatic mistakes. We considered the effect of meteorological data temporal resolution (5, 10, 15, 20, 30 min; 1, 2, 3, 4 h) on a stand-alone hybrid system’s layout in terms of equipment cost, power supply reliability and maximum duration of interruption for monitoring equipment in the Alps. We have shown that lifecycle costs could be strongly (order of magnitude) underestimated for off-grid systems, as well as their reliability overestimated. Lower temporal resolution data lead to the underestimation of energy storage charge–discharge cycles (considering depth of discharge too)—real batteries are to be replaced more often, which matches our practical experience as well. Even a 5 to 10 min decrease in weather data temporal resolution leads to the estimated annual expenses being halved. In general, we recommend using 30 min. resolution.

Inverter Heat Pumps as a Variable Load for Off-Grid Solar-Powered Systems

“…The calculation is based on consideration of energy balance between generation and load. The numerical model used is described in detail in [29]. The following describes the main additions to it.…”

“…To simulate the operation of various stand-alone power system configurations, weather data with 1 h temporal resolution of solar irradiance, air temperature, and wind speed are used. Such high temporal resolution is necessary for a detailed behaviour analysis of an off-grid system based on RES [29] (it is impossible using monthly averaged data).…”