Analyzing the effect of forest fire air-borne particulate and smoke in the atmosphere on solar electric power outputs. - this blog was the result of a great question posed on our

Facebook page.

Solar electric output from a photovoltaic array is affected due to the smoke in Kelowna, but by how much? Fortunately this can be accurately assessed by analyzing the inverter output traces for two separate days.

By reading the inverter daily electrical output in kilo-watt-hours (kWh) for energy generated on a clear-sky day with little visible cloud cover; then comparing this output with the output from a smoke filled day, a reasonably accurate measurement can be determined.

Graphical representation is for the daily solar energy on a clear blue-sky day, the total daily electrical energy output recorded on the solar inverter is 45kWh. This output was recorded on August 7, 2018.

This trace indicates power output and the effects of smoke, which was present in the Okanagan Valley due to forest fires burning in British Columbia. Total daily output of 39.5kWh, recorded on August 17, 2018.

The difference between the green trace ( clear day) and the blue trace (smokey day) represents the power loss due to the smoke preventing some of the sun’s rays from striking the solar panels. This represents a 12.5% drop in daily power output compared to the reading taken ten days prior.

Only smoke was blocking the passage of sunlight from reaching the solar panels (difficult to see cloud on smokey days); also, it must be reasonable to expect a marginal drop in this output with respect to the power output taken ten days prior, due to the days getting shorter as the sun travels towards the winter solstice.

Morning sunrise between 6:45am and 9:45am; the morning dew is hanging in the air, taking longer to clear indicating the air is taking time to warm up.

The financial loss due to a reduced generation output from the solar system caused by the smoke can be calculated by multiplying the kWh difference (5kWh) by the cost for each kWh lost ($0.15 per kWh), this equates to around 75 cents loss for this day (August 17-2018). Taking into consideration these daily losses due to smoke over the life of the system (25yr plus) bears no relevance in the grand scheme of things.