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re: information
22 feb 1998
gary beckwith wrote:
>courtil@ibm.net wrote:
>> i am very interested in building a small solar system but i don't know
>> much about combination of photovoltaic system and propeller connected to
>> batteries that will power domestic equipment that need 120volts.
this "propellor," ie wind-electric/moulinet might be a big help in canada.
a bare 50 w pv panel that costs $300 might collect 100 kwh/year of electrical
power with a value of $10/year at 10 cents/kwh. a 375 w windmill that costs
$500 might collect 2000 kwh/year with a value of $200/year. can you make
your meter run backwards with any excess power?
>> in fact when i analyze this, a panel can only generate 10w per hour of
>> sun in a battery that can stock 12w
>
>...there's a problem also with the batteries. they store energy
>in amp-hours, not watts.
that's how people talk, but energy is measured in watt-hours, joules,
ergs, horsepower-hours, etc., so batteries store energy in watt-hours.
amp-hours need to be multiplied by volts to make units of energy.
a 100 a-h 12 volt battery can store 1.2 kwh, 100 a-h at 24 volts stores
2.4 kwh. a 55 gallon drum of solar-warmed water cooling from 130-80 f
stores 6.5 kwh of heat energy. a typical house in vermont requires about
5 times more heat than electrical energy, before replacing incandescents
with cf's, and so on. how do you heat your house?
>...you need to make a list of the appliances, how much energy they use,
>and how many hours per day you want to use each appliance. this will
>help you figure out the total energy demand, which must be in watt-hours
>per day.
or divide your electric bill in kwh/month by 30.
>> is this kind of system can generate 1,000kwh in a month?
a 10 watt pv panel might make 50 wh/day or 1.5 kwh/month.
nick
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