This page is the basic outline for control strategies for removing snow from PV modules in northern climates using a heating mechanism to melt the snow. Why is this a problem? See Effects of snow on photovoltaic performance and Impact of Snow and Ground Interference on Photovoltaic Electric System Performance
Potential Inputs
Sensor inputs for determining snow cover
- temperature
- snow depth via sensor
- optical occlusion
- optical reflection from modules
- force sensor
- module image
- off-site weather data/ past and/or predicted
- reduced PV output as compared to heated (always on) pyranometer
- IR sensing
- wireless/wired connection to web server that has current weather information (also a dispatch strategy)
Potential Outputs
Electrical resistive heating using one of the following methods:
- heat strips on back of panel
- heat strips on edges of panel
- electrically conductive optically transparent front retrofit of panel
- electrically conductive optically transparent front integrated panel (e.g. top layer of glass, in eva, etc.)
- external heater
- liquid heating on edges of panel
- liquid heating underneath panel
Potential Dispatch Strategies
- always on
- manual on/off
- on every morning, or other set amount of days
- melt while snowing
- melt every snow fall
- melt on predetermined time -- dynamic so changes during snow season based on historical data or current weather trends
- melt on predetermined depth or weight of snow or optical occlusion
- change as a function of time, temperature, output, solar flux
- wireless/wired connection to web server that has current weather information (also an input strategy)