In my Year 2 Report, I mentioned that we would have needed 2 more panels to generate more electricity than we consumed. That’s because the meter reading at the end of year 2 (March 26, 2021 at 1:30 PM) was 01098 and our worst panel had produced about 257 KWh/year.
What a difference a year makes. On March 26, 2022 the meter reading was 00387. This means we consumed 712 KWh less than we produced this year (1098 – 387). The 3 year reading for our worst panel was 778.2 KWh. So one more panel that was at least as good as our poorest producing panel would have put is in the black (the meter reading would have been negative).
Does this mean we produced 712 KWh more this year than last year? No. Here are the meter readings and total production for the first 3 years:
| Meter Reading | Annual Total | Cumulative Total |
| 0455 | 9.67 | 9.67 |
| 01098 | 9.1 | 18.77 |
| 00387 | 9.33 | 28.1 |
We produced a little more in year 3 than in year 2 (230 KWh), but the main reason for the improvement was a reduction in consumption (482 KWh). This reduction allowed us to build up a greater surplus going into the winter months so that we only had an electric bill for two months of the year, for a total of 200 KWh. The only reason we had these two bills at all is because BGE, our utility company, zeroes out the surplus after the April reading and sends us a check for the surplus supply amount we generate each March and April. This means we do not have enough credits by the end of the winter and so we have to pay for what we do not produce those last few months.
As you may recall from previous posts, the electric bill is divided into supply and delivery (and smaller amount for the meter charge and taxes). The delivery amount is about 3.5 cents per KWh.
| Date | KWh | Rate (Supply) | Check Amount |
| 5/20/2019 | 446 | 0.0879 | 39.20 |
| 5/22/2020 | 535 | 0.082809 | 44.30 |
| 5/24/2021 | 913 | 0.071446 | 65.23 |
| Total | 1894 | 148.73 |
I will not get a check for this year’s surplus until late May, but using .08 per KWh as an estimate for the supply rate and 300 KWh for the March surplus (300 * .08 = $24), we can guess that the total March/April surplus by the end of year 3 is about $173.
The $24 amount is interesting for the March surplus, as the cost for the 200 KWh that we got charged for in January and February (due to the zeroing out the previous March) was approximately $24 as well. If BGE did not zero out the surplus each year we would have essentially had no electric bill this year, except for the (approximately) $100 per year they charge for the meter (labeled as a customer charge).
Looking at this over the 3 year period, we used 129 KWh more per year (averaged out) than we consumed. This is calculated by dividing the meter reading (00387) at the end of year 3 by 3. Rounding a bit, using 0.12 per KWh or $120 per MWh, in theory we should have paid on average $15.48 per year, or $46.44 total over three years. In fact, because we are not compensated for the delivery portion of the March/April surplus, we paid more. Following is the approximate reconciliation:
| Amount | Comments | |
| Amount paid | $595 | What we sent BGE over 3 years |
| Meter charge | $300 | Approximate (varied from $8.22 – 8.75/month) |
| Net paid for electricity | $295 | $595 – 295 |
| Surplus BGE paid us for | $173 | includes guess for March 2022 |
| Actual bill for electricity | $122 | $295 – 173 |
| Delivery not reimbursed | $77 | Approximate using .035 per KWh |
| Net should have paid | $45 |
So the amount we should have paid reconciles with the amount we actually paid. Effectively, the March/April surplus zero-out cost us an additional $2.14 per month.
How did we reduce consumption by almost 1/2 MWh? I’m not sure. Some of it was intentional. We found a few more bulbs to convert to LED. We set our thermostats a little differently, focusing on comfort at the end of the house we were in and reducing/increasing the setting at the other end. We took a couple of short trips, 3-5 days each and set the thermostat higher while we were gone. Finally, my wife required more sleep this year due to her health, and so she was generating less electricity while sleeping. I expected we would use less over time as we got older and as appliances got more efficient, but we have not replaced anything yet.
I have noted previously that the amount of solar energy we convert to electricity is highly dependent on how cloudy/rainy it is. Panels theoretically degrade slightly as the year goes on. However, we can see from this snapshot that more recent quarters sometimes produced more electricity than older quarters.
One last picture, to show that we had surpluses (or accumulated surpluses to zero out our bill in every month this past year but two:
One last note. As our annual production was over 9 MWh each year, we produced our 28th SREC on March 22, 4 days before the end of year 3.
Please respond with any comments or questions. I enjoy helping people decide if solar panels are a good opportunity.