Sunday, July 7, 2024

Yes, Fixing Last Year's Solar Weirdness Mattered, Big Time

Hindsight is always 20-20, as the saying goes, and as we approach mid-summer my solar system's strong performance during the month of June is reminding me how poor performance was at this time last year. 

You may remember last year's weird phase, which began in May and wasn't fully corrected until early August. The inverter was swapped out for a fault comms board, and then a bad crimp connecting panels to the inverters was replaced. Once it was all fixed, and a communications problem solved with a Wi-Fi router, production soared.

And here's how I now know that my instincts were right then: Performance this summer has improved versus last summer significantly. Compare June of '24 in green to the same month in '23 in blue. (June of '22 was the month the system was installed, so it was a partial month.) Production came in just shy of 1.3 mWh versus 510 kWh, for an improvement of more than 2.5x.

Even so, the system ended the month consuming slightly more power — 1.35 mWh — than it produced. We had the power-gulping pool heat pump running for several days during June. Also, the electric water heater is running, and heat waves meant running the AC system aggressively. 

The good news is that prior solar production starting in September and running through May had by June created a sizable generation bank with our utility. We don't get paid for the power we export to the utility grid, but we do get ongoing bill credits for it, and as of June the added value of those credits amounted to about a third of what we consumed from the grid in all of 2023.

Even better: A quick check of the bill for the two-month period ending July 2 says that this generation bank has only grown bigger since then, to north of 3 mWh. What it all means is that everything that consumes power in July and August, and likely for the rest of the year will be free. And the long sunny days will extend that billing credit even further. And once the hot weather to sunny and cool days in September and October, the cycle will repeat itself.

Also, a day in June brought the system's highest single day of production so far: 92.4 kWh. It was a perfect, cloudless day. I was always curious to know what the production graph would look like under ideal conditions, and now I know. This day's performance beats two prior records set in April, the first of which occurred on Earth Day.  

My utility, Central Hudson, charges me $19.50 per month in basic delivery charges. This means my utility bill is now basically a gas bill with a minimal charge for electrical grid service. 

I have some other encouraging news on that front. As I told you in the last post, the hybrid electric water pump is in and running. And the early results are promising. I compared the current gas bill to the one from the same period last year. It was about $67 lower. I can attribute to a lower average daily cost for gas of $2.24 versus $3.33 in the same period last year. But consumption is also lower: We used 47 Ccf of gas this June compared to 80 in the same period last year. That's a reduction of more than one-third. 

It won't always be so good because we still heat the house, dry our clothes, and cook with gas. But as I start the work of trying to reduce our overall reliance on natural gas, this is a good start. Next year I plan to get a heat pump to replace the air conditioners. If I understand correctly, it will heat and cool the house, and the gas furnace will be on standby for the exceptionally frigid days of deep winter. I also want to replace the gas range in the kitchen with an induction cooktop. I hope to have more progress to report on this front soon. 

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