Posted by: Li Ling Young | August 28, 2012

Getting that big, fat pig-of-a-water heater to fire

For one week our solar system is operational but we’re not selling electricity to our utility.  Until we have our electrical inspection and the utility replaces our meter with a reversible meter any electricity we generate is a freebie for the utility.  As a result, we can only benefit from our PV system if we are using electricity at the same time it’s being generated.  This leads to a sometimes comical situation in which our energy-consuming activities are delayed until we can do them for free.  I think of it kind of like eating local, but on a daily cycle instead of a yearly one.

Remember, this is only for the one week.  After that the utility credits us for all the electricity we generate, and we draw off that credit whenever we use electricity, even if it’s at night.  In case you’re wondering, we do actually use our own electricity when we are generating even after the whole keeping track and credit thing goes into effect.  It’s actually better for everyone that way because there aren’t any transmission losses, so the “efficiency” is a little better than it would be if the electricity were coming from Connecticut, say.  Also, my neighbors can use the electricity without the transmission losses, so really all our electrons are getting used up here on our block even when we’re selling our electricity back to the utility.  But all to the good.

So, today is the first day I feel intellectually equipped to try this seasonal solar eating.  Yesterday I forgot and turned on the dehumidifier and ran the wash 1) with the inverter off, and 2) at night.  Today I saved the breakfast dishes and the clothes drying until the sun could help with everything.  But it’s cloudy!  So, waiting, waiting.  Finally, the sun comes out and the inverter shows over 3000 watts.  OK, on goes the dishwasher, the dehumidifier, the refrigerator is already running, the wet clothes go in the dryer, I’m washing the pots and pans by hand.  Oops, we overshoot.  I’m not really sure why this is, but our whole-house watt meter is over 6,000 watts.  Anyway, I carry on using electricity like… well, there really isn’t a good metaphor for this that’s not totally cheesy, but you get the point; make hay and wash dishes while the sun shines.

Using about a kilowattInverter display shows about half-a kilowatt electricity generation.

After I’m done with dishes I go check the water heater.  Because we have an 80 gallon water heater it doesn’t come on every time we use hot water.  It actually takes quite a bit of hot water use to drop the tank temperature enough to make the water heater come on.  But NOW is the time to make hot water, so I need to do something to get that water heater to fire.  I take a shower.  Now, generally a shower will get any water heater to fire, but we have very low flow shower heads and after a pretty long shower in which I actually wash my hair (also pretty long) I still haven’t used enough hot water to get the durn thing to fire.  Meanwhile, the sun keeps going behind clouds and the household electric use and the solar-generated electricity are matching a bit better.  I try one more thing.  Having already washed the laundry last night I have to look around for something that needs hot water.  The cute but well-abused rag rug in front of the sink and next to the garage door is feeling pretty sticky, so I throw that in the wash (all by itself!) and wash it in warm.  10 mintues later…  Still no water heater action!  At this point Nicholas comes home and I relate the whole thing to him.  He says…

Turn up the tank temperature.  Yes!  Of course.  Make hay.  Do we need the tank hotter?  No, but it’s a handy place to store energy.  And when it comes time to use hot water we’ll just use it more slowly because its a little hotter.  As soon as Nicholas touches the temperature dial the water heater fires.  It’ll go for a while because the tank is so big and you have to add quite a bit of energy to that much water to raise it back above the temperature setting.  Meanwhile, the sun is behind a cloud again.  Oh well.  Tonight I’ll turn the tank temp back down because we don’t really need the water kept that hot.


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