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My first 7 weeks live

J

JerseyBoy

Jan 1, 1970
0
Hi,
My PV system - 7.22 KW (38 190W panels) went live on November 1.
The system is in central NJ. The panels are mounted on a 38-degree
pitched roof facing due south. So far, according to PSE&G, I've
generated 517 kWH through December 17.

Does this production sounds about right? It's the
darkest part of the year, granted, but I'd have thought I'd have
gotten more out of it by now...

Thanks,
Elli
 
S

Steve Spence

Jan 1, 1970
0
JerseyBoy said:
Hi,
My PV system - 7.22 KW (38 190W panels) went live on November 1.
The system is in central NJ. The panels are mounted on a 38-degree
pitched roof facing due south. So far, according to PSE&G, I've
generated 517 kWH through December 17.

Does this production sounds about right? It's the
darkest part of the year, granted, but I'd have thought I'd have
gotten more out of it by now...

Thanks,
Elli

That's about right for your location and time of year. 2 full sun hours
per day is the best you can ask for, and not every day is sunny.
 
M

Martin Riddle

Jan 1, 1970
0
JerseyBoy said:
Hi,
My PV system - 7.22 KW (38 190W panels) went live on November 1.
The system is in central NJ. The panels are mounted on a 38-degree
pitched roof facing due south. So far, according to PSE&G, I've
generated 517 kWH through December 17.

Does this production sounds about right? It's the
darkest part of the year, granted, but I'd have thought I'd have
gotten more out of it by now...

Thanks,
Elli

Yes like steve says.

7.22kw * 0.75 = 5.415 kw , system efficency is ~75%
Assuming 2 sun hours a day... and 47 days
5.415kw * 2hr * 47 = 509.01kw
 
J

JerseyBoy

Jan 1, 1970
0
Ron said:
Probably about right, depending on where you are in NJ, and surely within
the limits of expected variation.

As a comparison, I have 1.98kW of panels oriented about 25° W of due south,
at a roof angle of about 39° degrees (my latitude is 45°) and for that time
period the panels generated 137.7 kWh. We are located near Eastport, ME
and given our location and lack of optimum orientation should generate less
than you.

If I had 7.22kW of PV, I should have generated about 502 kWh.

To make a better comparison, we would have to increase that number by some
factor to allow for more sun in your location in NJ, your more optimum
panel orientation, and the ten hours or so that my panels were not
generating anything due to the batteries being full.

On the other hand, we would have to decrease my figure to account for
conversion losses in your inverter (my measurements are of panel output
directly) so the bottom line would probably be pretty much the same.
-- ron (off the grid in Downeast Maine)

Are you saying that there is significantly less loss in a battery system
than a grid-tied system?

-- Elli
 
S

SJC

Jan 1, 1970
0
JerseyBoy said:
Are you saying that there is significantly less loss in a battery system than a grid-tied system?

-- Elli

I have heard batteries can be 90% efficient (depends on conditions)
and a charge controller might be 90% (let's say), that would be about
80% efficient DC in to DC out. Now put it through a 90% efficient inverter
and you get .9 x .8 or about 72% (plus or minus) efficient DC in to AC out.
Compare that with DC from panel to grid at 90% efficient, for the inverter.
 
J

JerseyBoy

Jan 1, 1970
0
SJC said:
I have heard batteries can be 90% efficient (depends on conditions)
and a charge controller might be 90% (let's say), that would be about
80% efficient DC in to DC out. Now put it through a 90% efficient inverter
and you get .9 x .8 or about 72% (plus or minus) efficient DC in to AC out.
Compare that with DC from panel to grid at 90% efficient, for the
inverter.

Actually my confusion about my production was due to my misunderstanding
of the operation of my net-meter. I had produced much more than 517Kwh.
The net-metering really should be called a "net-net" meter. It does
not measure gross consumption and production, only what is drawn from
and output to the grid. Any internal usage must be measured by the
inverters themselves... The 517Kwh only represented my back-feed
generation...
 
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