[Greenbuilding] [BULK] Solar electric configuration details

[Lawrence Lile]

Yes, the solar hot water heater is going on the other end of the roof.
I'm not even going to calculate a payback on it, I'm sure it is plenty
short. 

I'm starting to rethink my loads somewhat.  Checking more accurately, I
find that my floor heat system uses about 170 watts, and won't run but
10% of the time on a peak heating day.  That can be served by a single
130W photovoltaic panel with juice to spare.  This would be worth it
without figuring any economics, just for peace of mind during
emergencies. 

I'll put the freezer in the garage, on grid power, where half the year
it can enjoy some free cooling and the other half it is shaded and not
increasing my interior cooling load.  Loading up the extra freezer space
with ice jugs provides a handy item to take along on the next float
trip, while helping the freezer ride through any power outages.  So we
can skip that load.  


Maybe I don't back up so many lights - I think I can separate them out
somewhat.  Same with computer equipment.  A laptop is more efficient,
and the external laptop power supplies may be more tolerant of choppy
modified sine wave inverter.  I use my laptop on an cheapie inverter in
the car all the time to run mapping programs, with no problems

If I can whittle this down to maybe one 120VAC circuit, 2 solar panels,
a cheap inverter, a couple of batteries and a decent charge controller,
then it becomes a doable system that doesn't break the bank.  We've
found from experience that the charge controller is the Achilles heel of
the system - a cheap one kills off expensive batteries, and the homemade
hacked ones we tried killed batteries like Attilla the Hun killed
villagers. 

As you can see, despite bad economics I'm deadset on finding a way to
justify this project!  
 
Lawrence Lile, P.E., LEED AP