Is a large grid-tie system worth the cost?

 I read this HSW question "how many solar panels do I need to power my
house?"
http://home.howstuffworks.com/question418.htm

The article quoted about 600 watts per hour at 24 hours.
 It then went on to say you would neen at least a 17'x17' array and it would
cost about $16,000

It also implied 600 watts per hour was a low power consumption and that
solar power is really not worth it.

Are these numbers close?
How many watts per hour does a 185 watt panel usually generate? (New York)

I would like to avoid a hugh maintnence battery backup system but the
electric bill is about $160 a month. If I could get a system for $16,000 it
would pay itself off in 100 months asuming no maintnence is needed.

I don't have an electric bill handy to see if my power is that much higher
than the quoted house but on the listed figures if I can power the house on
$16,000 it's a go. The electric bill of 160/month over the next 20 years is
around 40 grand.

At that rate if the system cost 20 grand and only lasted 10 years before
having to be replaced it would still almost be worth it.

I still have to figure how much power is being used and do some homework but
do you think it's worth it?

 

Ohohoh. Welcome to alt.solar.photovoltaic. Now leave, and don't
come back till you know the difference between power and energy.

Nick

 Nick Pine (whom I ordinarily respect) wrote:


A little severe on the obvious newbie, don't you think?  At least he's
not trying to run a fuel cell off a bicycle-electrolysis system at
over-unity :-)

Just a hunch here, I think at $160/month for hydro you need to examine
conservation first and generation second.  If your hydro cost you 10
cents per kwhr you'd get about $500/annum out of your 'system' a far cry
from the $1920/annum of your current bill.

Are you heating electric?

Glenn

 Saludos desde www.solener.com
Antonio Vela Vico
Greetings from www.solener.com/index_e.html

 

Well, Nick's right in that you have some terms and units mixed up, but he is
being a bit rough on you.

Energy is measured in watt-hours, or kilo-watt-hours (a kilowatthour is 1000
watt-hours).  Power is the *rate* of energy flow/use/production.  Power is
commonly measured in watts or kilowatts (1 kilowatt is 1000 watts).

  If you know the flow, and how long it flows, you can calculate the energy
that flowed over that time interval by simply multiplying the flow times the
time it flows.  So a 100 watt lightbulb uses energy at the *rate* of 100
watts.  If its left on for 5 hours, then the total energy used is 100 watts
times 5 hours = 500 watt-hours (or, 0.5 kilowatt-hours).

So a 185 watt panel will generate (in full sun) 185 watts of *power*.  That
means it will generate 185 watt-hours of energy in one hour of full sun, 370
watt-hours of energy in two hours of full sun, and so on.  If it is mounted
properly and aimed correctly for your latitude, it will always generate
energy at the rate of 185 watts *in full sunshine*.

I'm, in NY also, so I know that you don't always get 'full sunshine', and
that is where your location becomes important.  Also being in NY, I'll
*assume* that your electric rate is about the same as mine, at about 13
cents for each kilowatt-hour (often abbreviated kWhr).  So if the *electric*
portion of your bill (not including any natural gas) is $160/month, this
means you're using something like ($160/month ) / ($0.13/kWhr)  = 1231 kWhr
of electric energy per month.  That is somewhat high (according to Niagara
Mohawk's 'typical' usage) unless you have electric heating.  But if you look
at your monthly bill, you can find the meter readings from last month and
this month, and the total kWhr used.  That's how much electrical *energy*
you bought from the utility last month.

You could be using that 1231 kWhr by having a 1700 watt load on for the
entire month (30 days is 720 hours, so 1700 watts X 720 hours = 1 224 000
watt-hours or 1 224 kWhr).  Or you might have an electric load of 300 watts
on all the time (300 watts X 720 hours =  216 kWhr) *and* a 4229 watt load
on for only 8 hours a day (30 days X 8hr/day = 240 hours/month.  240 hours X
4229 watts = 1015 kWhr)  for the same total electrical energy (216 + 1015 =
1231).

A solar system to support that much load would probably cost more than $20
000.  But there are solar systems that can *reduce* the amount of
electricity you have to buy from the utility.  These 'grid-tie' systems
supply electricity to your home when the sun shines, and if you don't need
the electricity right then because you're not home or something, the
'excess' is sent to the electric grid.  This will actually turn your meter
backwards, so you get to use electricity from the grid later for free.  This
is 'net-metering' and you can find more about it by doing a search for
'net-metering'.  In NY, the law provides for net-metering for SOLAR
developed electricity only.

Another way to reduce that $160/month electric bill is simple conservation.
I know it doesn't sound as high-tech, or new-age as solar collectors on the
roof, but it is simple, proven, and often has shorter pay-back than any
other alternative.  Residential customers in NY can ask for a FREE energy
audit from their utility.  But you can find a lot of the same information on
the 'net.

Anyway, welcome to alt.solar.photovoltaic

daestrom