News and Views From my kids accomplishments, to my heretical perspective of the world

Here’s a graph of our power usage from SRP so far for the Feb 22 – Mar 21 billing period. We’re just about breaking even, as the days get longer and warmer. We’re getting more sunlight and therefore more power, and using less for heating.

The days stand out when we do laundry or a lot of cooking, though clouds can also force us to buy more. There are several of those nice days when we sell power back to SRP.

That’s how much my electric bill was this billing month (which ends on the 17th). Last year it was $174.09. I guess my solar panels are starting to pay back! And $15 of that is a fixed fee, so we really only bought about $15.71 worth of electricity from SRP.

Of course, it’s not really a fair comparison since we were gone 3 of the 4 weeks covered by this bill. Before we left, the run rate was predicting a bill of about $80. Most of the days we were gone the system made more energy than the empty house consumed. Apollo was here, but he usually leaves the thermostat alone and rarely turns on the TV. Derek came over every day and watched some TV, but not nearly as much as Gisele and I do.

Anyway, the March bill will be a more fair comparison.

Here’s a graph showing the energy I’ve used since installing the solar panels two and a half weeks ago. The blue is energy I have bought from SRP, and the red is energy the solar panels have generated.

You can roughly infer the weather from looking at the graph. The sky has been clear except for some high thin clouds on January 3rd. The solar energy is down a little that day. And the total energy used each day has fallen as the temperature has gone up, until yesterday when it was cooler.

Cumulatively, I’ve bought 412 kWh from SRP, and generated 580, or about 61% of my total consumed energy. There are cooler days forecast, so that ratio is probably going to come down.

I got a burr coffee grinder for Christmas this year. I’m really impressed by the difference it makes in the taste of the coffee.

The theory is that a blade grinder just whacks the beans into smaller pieces, with lots of variation in size from powder to big chunks. The burr grinder yields a much more uniform size piece.

The result is that I can make coffee that tastes stronger without the bitter taste that can result from lots of powder. It’s very noticeably better.

Here’s a graph showing the the progress of our two power meters over about 4 days. The red line is from the meter that measures the solar power we generate. The blue line is the SRP meter. The vertical axis is in kWh.

Notice the solar meter does a “stair step”, rising during the day, then completely level at night. The SRP meter, on the other hand, rises all night while we heat and light our home, then falls each day while we feed power back to SRP.

The solar meter is rising a little faster overall than the SRP meter, indicating that our solar panels are providing a little more than half of our total energy.

I estimate that in March, April and May we should generate more energy each month than we use. The days are longer, so there is more sunlight to harvest, but it won’t be hot enough yet to use much cooling. My electric bill for those months should be zero, except for the monthly service charge of $15. We’ll see — I’ll certainly report on it.

Our solar energy system finally became active today. SRP (the local power company) was here at 9:00 am, and did the final connection.

Since then (it’s now 3:00pm) we have generated about 24 kWh. Of that, about 14 were sold back to SRP, and we have used about 10.

They installed a new meter that was set at zero this morning. It now reads 99986, showing that net energy has flowed out. I expect that after heating the house tonight with no sun shining I will wake up and find the savings erased. I noticed that when I turned on the heat pump, the direction arrow reversed, showing that we don’t generate quite enough to run everything else in the house and the heat pump too.

Peak energy during the day was 5100 watts; not bad for a winter day with the sun lower in the sky. Theoretical maximum is 8000 watts, but I will never see that due to inherent losses in the system.

I’ll publish some data after it has run for a couple of days.

SRP, the local power company, sent me an email today scheduling the “commission” for next Wednesday, Dec 21, 6 days from now. So it’s nice to finally have a firm date, but it’s hard to understand why it took so long.