Site icon John S Martinson (

UPDATE: Year One with Rooftop Solar

Our rooftop photovoltaic solar array went live at the beginning of March, 2015 and since it has been a year, I thought it would be a good time to give my readers an update as I have been keeping monthly tabs on the performance of the system. So here is a quick chart demonstrating the performance of the system:

Date is the month-year of the bill from our utility

Ave Fº is the average temperature for the billing period

ADC is the average daily cost of electricity from the utility

from APS is the total electricity in kWh received from the utility

to APS is the total electricity in kWh credited by the utility (net metering)

Net is the net electricity in kWh (electricity received minus electricity credited minus the previous month’s kWh credit)

COST is the total charges for electricity service for the month (including taxes)

As you can see, the Net dwindles during the hot summer months as our use increases and 6 of the months we are paying the minimum possible bill which is about $40.50. Annualized, electricity now costs us an average of $104.62 per month. In prior years to our bills ranged from $428 per month to as high as $862.00 per month, a substantial savings. Now just need to work on those fat months.

I hope to put the system online this year so readers can view the daily performance of the system live.

Finally, the icing on the cake is that we are reducing our carbon footprint substantially, thus contributing in our small but meaningful way to mitigating climate change.



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