Signs of spring

So far, April 2011 in Livermore is (as, I think, in many other places) turning out to be one of those “if there was such a thing as normal weather anymore, this wouldn’t be it” months. We’ve had hail (which is really rare hereabouts), driving rain and wind, and–not here but elsewhere in the Bay Area–even small twisters, I think.

But there are also increasing signs of spring, and I find that we can spot seasonal timemarks (like landmarks, but temporal) in more than one way.

Take yesterday, for example. One sign was that it was over 70 degrees for much of the afternoon. But that was also true in some days in February.

The other sign: We hit 16kWh (kiloWatt-hours) from our solar (photovoltaic) system, for the first time in 2011.

We’d gotten ever so close on three other wholly-sunny April days (15.94 in one case), but yesterday we made it.

Here are the milestones for 2011*–noting that we’ll get better than 9kWh on a reasonably sunny day even in December:

  • January 20: 10 kWh
  • February 1: 11 kWh
  • February 22: 12 kWh
  • March 12: 13 kWh
  • March 28: 15 kWh
  • April 15: 16 kWh

With luck, and assuming very little loss in efficiency from last year, we should hit 17 kWh in late April. I don’t believe we ever got to 18 kWh last year; at some point, very hot days cause a drop in efficiency.

Why no 14 kWh? It was cloudy enough during most days March 13-27 to dampen generation.

Yes, the meter’s “spinning” backwards (OK, so it’s an LCD readout with no physical manifestation)–overall, we average about 11 kWh/day electrical use, with considerably less on days we’re not drying laundry. So, typically, from mid-March on, we start generating more power than we use–and, for PG&E, that’s most useful in June-August, when we’re generating most power during the hot middle of the day, when there’s also peak demand for electricity.

Does photovoltaic and other renewable actually mean anything? In California, absolutely: The two big utilities didn’t quite hit the 20% goal for 2010, but they came close (more than 17% of PG&E’s electrical generation last year was from renewable sources, which doesn’t include big hydroelectric facilities)–and the new goal is 33% in 2020.

Now, to wait for the fruits of spring to arrive at the Farmers’ Market…as my wife said, especially for folks who don’t eat apples (she can’t eat them, I don’t care for them) but love fruit, April really is the cruelest month.

*No, I don’t obsessively write down our generation each day. Our SolarCity installation includes its own wifi and a custom web page for us, with half-hour data points each day and daily data points on weekly and monthly graphs; it took me five minutes to determine those timemarks.

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