Wednesday, July 11, 2018

Suburban 5-4-and-a-Door Solar: How Much Power do you Generate?

We now have a year's worth of data to play with, and one of the most asked questions is "how much power are you generating from your panels?" That can be a difficult question to answer because it depends on the month, the weather, the clouds, the pollen (probably) and other factors.

We took the generated power numbers from every day for the year ending on June 30, 2018 and put them into a histogram to see exactly what our power generation looked like over the year. We have a south-facing 6.875kW array with some minor shading in the mornings.

The way the histogram works is that the first column (0kWh generated) represents exactly zero kWh. Subsequent columns represent the range from the previous number to the number shown (just over 0 to exactly 2 kWh, just over 2 to exactly 4 kWh, etc.). The smart meter didn't record for the first 5 days, so there are a total of 360 days represented.

  • Our best day was 33.3kWh generated on March 14, 2018. March was an especially good month with a lot of sun and had a few days in the 30kWh range.
  • Our worst day was 0kWh on September 12, 2017. September had a couple of very poor generation days due to some major storm activity. Even so, zero was startling to see. Fortunately it only happened once.
  • The average power generation in a day is 18.4kWh. Perhaps more relevant, the median power generation in a day is 20kWh.

On a per-month basis, the data shows numbers ranging from 354kWh in December to 688kWh in April, but those can be highly influence by weather so your mileage may vary.

No comments: