Category: return on investment

In 2024 we generated a grand total of 7,501.23 kWh of electricity–more than last year but not quite as much as 2022, even with the additional string of panels. Shows how big a factor weather is in productivity.

We used 2,761 kWh running the house and charging our EV, significantly less than last year, while 4,740 kWh went to the grid. April was the biggest generating month, when the system cranked out 777 kWh.

Surprise, surprise, electricity rates rose again in 2024, peaking at a whopping $0.27/kWh. Supply prices continue to slowly decline, but Central Maine Power is now getting $0.12/kWh for delivery, nearly as much as the supply cost. Crazy.

Our clean power production saved approximately 17,000 lbs. of carbon emissions over the past year.

After 7 years we’ve earned back $9,442.25 or 59% of the original investment. As electric rates continue climbing to unheard of levels, we should recoup the cost of the system in the next 3-4 years.

In 2023 we generated 7,341 kWh of electricity–not quite as much as last year, even though 2023 was the first full year with the additional 1000 kW of generating capacity. Not as much sun in 2023 apparently.

The house and car consumed 3,076 kWh while we sent the excess 4,264 kWh to the grid, knocking our electric bill down by $1,812.17. Rates rose again in 2023, costing $0.26 per kWh, mainly due to Central Maine Power hiking their delivery rate to $0.09/kWh. Supply cost actually dropped during the year to $0.16/kWh.

Six years in, we’ve now earned back $7,429.70 or 47% of the original investment.

2022 was the fifth year for our rooftop solar system and at 7,569 kWh was the most productive year yet. That’s likely because we added a 4th string of panels to array #2 in October, raising our charging capacity from 6.4 to 7.4 kW. Definitely made a difference in those last 3 months of the year.

We used 3,126 kWh here and sent the excess 4,443 kWh to the grid, saving us a total of $1,240. Electricity costs rose sharply this fall but our existing contract with our supplier didn’t expire until November, but then it rose about 60%, so our rate of savings will increase this year. We’ve earned back $5,618 or 35% of the original investment.

Best month of production in 2022 was July, at 829 kWh, with May a close second. November produced a surprising 600 kWh, a combination of the additional panels plus a lot of sun.

We should see our biggest year yet in 2023 with the extra 1000 kW of charging power added by the new string.

Year 4 is “in the can” as they say, let’s have a quick look to see how the solar system performed in 2021. We generated 7,619 kWh last year, 7% more than last year and the most productive year yet.

We used 3,126 kWh of that power on premises and exported the remaining 4,493 kWh surplus to the grid, slightly more than we exported the first year. That saved us $1,075, the largest savings in one year so far, bringing the lifetime savings to $4,362–which recoups 26% of the system cost.

June was the biggest production month last year at 755 kWh, with March and May close behind. As usual, December was the least productive month although this year it produced a respectable 399 kWh. November was surprisingly strong last year at 552 kWh.

The only maintenance issue that arose this year was the computerized control unit, known as the MATE3s, which had to be replaced after it stopped communicating consistently with the internet (which it does to send data to the cloud-based system monitor).