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Sizing a grid tied PV System

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Michelle P

Jan 1, 1970
0
Hi all,
I have ordered a few books on the PV systems and cannot wait to start
reading them. Out of curiosity this afternoon I went down to the power
panel removed the cover and clamped on my Amp meter.
What I got with all the lights in the house on (as a test) and the Air
conditioner running was:
15.8 5.2 19.7 Which tells me I have 15.8 amps of combined 120/240
(1896/3792 watts) and 5.2 amps (624 watts) of 120 only load.
Should I go around and get the amp/watts off all my major appliances and
use some usage table to figure out what will work best? what is a
reasonable size for grid tied system?

Just want to have some information before talking to some companies.
Makes me look better and I will have some idea if they are trying to
snow me.

Michelle in Virginia
 
W

William P. N. Smith

Jan 1, 1970
0
Michelle P said:
reasonable size for grid tied system?

Well, the major advantage of a grid-tied system is that it's
relatively insensitive to the actual load your house presents to the
grid. Most places do net metering, so you'll pay back based on how
much power you produce, if it's 10% of your consumption you'll offset
10% of your power cost, if it's 10X your consumption you'll get a
check from the utility for 9X your power bill.

That said, you can figure your monthly power consumption by inspecting
your bills, and guestimate how many hours of "peak sun" you'll get,
and get a rough idea of what size system might offset 100% of your
power consumption.
 
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Mel

Jan 1, 1970
0
Solar Flare a écrit :
I doubt you will get a cheque from a utilty in any location.

Depends what country you're in.... this is an international newsgroup
y'know.



***


A resaonable size for a grid connected system is one that you can afford
and that will generate at least the equivalent of 30% of your yearly
consumption - less isn't very demonstrative and you risk being
disappointed.....

In all cases check out what investements you can do to get a better
coverage for the same size system (offereing yourself a flatscreen on
your pc or tv can be a good idea, a new super efficient fridge too,
shades and shuttere to reduce your a/c draw..... there are loads of
things to look at... these will (normally) up your coverage at a cost
cheaper than adding to your grid connected pv system)

More is fine but unless you live somewhere with a very good feed in
tariff (Germany, Spain, some partes of America, French Antilles...)
there's little point going much past the equivalent of 100% yearly coverage.




Mel
 
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Michelle P

Jan 1, 1970
0
William,
Well you info made too much sense and so easy.
My average for the last year is: 1285kWh, the high: 2220kWh, the low 670kWh.
Michelle
 
J

JerseyBoy

Jan 1, 1970
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Here in New Jersey, if I generate more than I consume, my energy delivery
company (using a 12 month look-back period) only credits me at wholesale
rates (currently 6 cents vs. retail: 13 cents). That's why oversizing a
system is not necessarily a good thing. The capital investment on the
overcapacity portion has a much longer break-even period.

When my system is up and running and I determine that I'm overproducing, I
expect to tweak my usage by converting gas appliances to electric as needed.

Elli
 
W

William P. N. Smith

Jan 1, 1970
0
Michelle P said:
My average for the last year is: 1285kWh, the high: 2220kWh, the low 670kWh.

Again, some of this analysis depends on your location and the details
of your net-metering 'contract' with your power company, but as a
SWAG:

Go for the low of 670KWHR/Month, or say 20KWHR/day. If you have {4,5}
peak hours of sunlight per day, you'll need {5,4}KW of solar panels,
which might set you back $40-50K installed.

On the high end, you might install 20KW of panels for $200K installed
cost, but that depends on a lot of factors that we don't know...
 
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