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5/28/2019 11:42:49 AM
It's been over a year since the Captiol Complex's first on-site solar installation started producing electric power. The 133.3 kilowatt peak direct current (kWp DC) array sits on top of the Minnesota Senate Building (MSB). After a year of logging production data, how has array performed? The Office of Enterprise Sustainability produced a series of simulations as it explored expanding solar on the complex. We can now compare how the array has actually performed relative to our simulations.
In total, the array produced 137,355 kilowatt-hours (kWh) of energy from April 25 2018 to April 24th 2019, or 1,030.4 kWh/kWp DC. The system produced less power than the simulated model. We believe that this is due to the incredibly snowy month of February. In general, it was a snowy season in the Twin Cities. According to the National Weather Service, the MSP International Airport accumulated 77.1 inches of snow (from July 1 2018 to April 25th 2019), that's 23 inches departure from the normal (54.1 inches). It was the 7th snowiest meteorological winter (December through February). February in particular was the 4th snowiest month on record with 39 inches. You can really see the effects of this snow strongly pronounced in the following graph.
The model calculates solar PV production using what's called the "Typical Meteorological Year" dataset. The dataset is a year of actual weather data that best describes a set of years.
Let's take a look at the monthly total kWh production.
Finally, here is a look at the degree to which the Minnesota Senate Building is powered by the array. Below, we plot the the median production ratio for each month. The production ratio is the sum of daily kWh produced by the array divided by the total building electricity consumed. We then calculate the median ratio for the given month. From the graph, we can see that in the month of July the median production ratio was 23%, meaning that 50% of the days in July were at least 23% solar powered.
At the Department of Admin, we're super excited to have good data on technologies such as this. We'll continue to monitor the array's performance. While PV installations can be low maintenance, performance monitoring is critical to ensuring the array produces at its optimal, avoiding emissions and high energy and demand costs.