Cloudy Periods

As mentioned before, a number of our electrical devices are supported by the off-grid solar installation at our house. But during cloudy or rainy periods, my undersized battery bank will drain to the point that the smart inverter switches to utility input. During these times, the activity recorded by TED may be more typical of “normal” households, albeit still at modest scale.

Two days of data when the solar input was mostly bypassed (solar re-engages at day 348.4). Local midnight corresponds to X.00 days, so that X.50 is noon and X.75 is 6 PM.

The refrigerator forms the visually dominant feature of this sequence, tirelessly cycling on and off. It can be easier to look at the bottom envelope of activity to sense the overall usage pattern. I note refrigerator defrost cycles at 346.94 and 348.36 days—corroborated by the longer cooling cycle after each heat pulse (see post on heat pumps). Most spikes are due to the microwave (or sometimes similar-power toaster oven). I recognize the lopsided signature of a clothes-washing cycle at 348.53, and the tell-tale two-horned visage of the dishwasher at 347.87. We hosted a dinner on the evening of day 347 (though the guests were likely unaware of the day number), which accounts for a higher-than-normal evening energy use (compare to evenings before and after), as well as the use of the dishwasher.

Summary Table

As a matter of convenience, I gather the results of the various measurements represented throughout this post. I crudely estimate the daily impact of each, based on our usage patterns—some of which are seasonal, and some of which don’t really apply to us (like the furnace, which we almost never use).

Activity	Energy (Wh)	Daily Use	Notes/Conditions
Garage Door Open	0.36	1.4	2 open/close per day
Garage Door with Light	1.5	6.0	2 open/close per day
Mowing Small Lawn	57	8	weekly, summer months
Clothes Washer Cycle	132	30	at 1.5 loads per week
Rice Cooker	180	50	at twice per week
Heating Pad, 1 hour	30	90	at 3 hr/day in winter
Sawing 40 ft of Stair Stringers	370	—	not habitual
Microwave, 5 minutes	150	150	5 min/day
Furnace Blower, 1 cycle	80	160	at 20 cycles/day (if used)
Mattress Pad, full-blast, both sides	60	240	8 hr/day, half-blast, winter
Space Heater, 1 hour	1400	280	at 12 minutes/day, winter
Refrigerator, 1 cycle	20	1000	efficient (40 W) fridge

Postlude

As I disclosed at the beginning, I was not aiming for any momentous conclusion in this post. And maybe a post with plot after plot of energy activities in my home is of little interest to people outside my household—and maybe only to half of those within, come to think of it. But hey, I learned something from each one of them, and hope the plots are worthwhile to others as well.

There are many appliances I don’t have, so cannot show. And our usage is modest enough that we seldom have lots of things happening at once. So it’s not as hard to disentangle events in these plots as it might be for more active households.

I would still like to test our almost-never-used air conditioning unit sometime and see how the thermal performance of our house in cooling mode compares to heating mode, and what kind of efficiency leverage we’re getting from the heat pump. I know many in the U.S. will cringe to hear it, and I’m not saying this to be mean, but we have yet to see temperatures this year in San Diego that call for cooling. Our July 4 was a cold and windy day. No wonder the fireworks all went off in a 15 second frenzy: they couldn’t stand the cold and wanted to hurry up the show!

Okay—Irresistible Aside

If you haven’t heard about it, a technical glitch caused the coordinated fireworks displays across San Diego to fire all at once during this year’s July 4^th celebration. I was at a party where we managed to get atop a local hill in time to see the Sea World fireworks a bit later, but missed the municipal debacle. So I had to watch a youtube video (or see here for a view of three displays in one frame). All I can say is that had I been close at hand to one of the accelerated displays, I would have been laughing so hard I might have had trouble breathing for the next several minutes. Many spectators were deeply disappointed and complained bitterly. But this would have been the best fireworks display of my life, and one I would never forget—unlike all the rest that become boring by the end and then fade into obscurity. Awesome!

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