What to expect ?

Arkansasoffgrid

Looking at Canadian Solar CS6P-P250 panels. Rated 250w, Pmax 181w, and Ptc 227.6w
What should I realistically expect from these ?

pleppik

Re: What to expect ?

In general, there's not much difference in power output between two brands of panel rated for the same power.

As for what you can realistically expect, that depends on your site: module position and shading. You can spend some time on PVWatts to get a pretty good idea of how much power they will produce over the year.

niel

Re: What to expect ?

often the ptc is more of a real world max. the real output depends on how much sun will hit the pv.

BB.

Re: What to expect ?

Off Grid for Little Rock Ark using PV Watts, fixed array tilted to latitude. Use 0.52 derating for AC based power usage. Say 6 panels * 250 watts = 1,500 Watts:



Station Identification



City:
Little_Rock


State:
Arkansas


Latitude:
34.73° N


Longitude:
92.23° W


Elevation:
81 m


PV System Specifications


DC Rating:
1.5 kW


DC to AC Derate Factor:
0.520


AC Rating:
0.8 kW


Array Type:
Fixed Tilt


Array Tilt:
34.8°


Array Azimuth:
180.0°


Energy Specifications


Cost of Electricity:
7.4 ¢/kWh






Results



Month
Solar Radiation
(kWh/m²/day)
AC Energy
(kWh)
Energy Value
($)


1
3.78
89
6.59


2
4.38
91
6.73


3
5.19
117
8.66


4
5.67
119
8.81


5
5.89
124
9.18


6
5.81
116
8.58


7
5.93
120
8.88


8
6.08
124
9.18


9
5.41
109
8.07


10
5.16
112
8.29


11
3.69
80
5.92


12
3.56
82
6.07


Year
5.05
1283
94.94




Toss the bottom three months and find 4.38 hours of sun minimum for "February break even month" (use generator/reduce energy usage during winter):

1,500 Watts * 0.52 AC off grid system derating * 4.38 hours of sun (Feb) = 3,416 WH = 3.4 kWH per day

That would be enough to run a "near normal" (lots of energy conservation) system with a full size energy star refrigerator, lights, laptop computer/LED TV, well pump, clothes washing machine).

We recommend around 5% to 13% rate of charge for a battery bank... And 10%+ for a full time off grid system. A 1.5kW array at 10% rate of charge would support:

1,500 Watts * 0.77 panel+controller derate * 1/0.10 rate of charge * 1/48 volt bank = 241 AH @ 48 volts (or 481 AH @ 24 volts)

That would be the basics... Largest (nominal) AC inverter on a flooded cell battery bank that would be "useful" for a 241 AH @ 48 volt battery bank would be around 2.4 kWatt rated inverter...

-Bill

Arkansasoffgrid

Re: What to expect ?

Reckon what I meant was with these ratings should I expect 181w or 227w during "peak output"

BB.

Re: What to expect ?

My "typical" rating:

250 watts * 0.77 panel+controller derating = 192.5 Watt (otherwise well designed system)

In cool weather/very clear conditions, you may get more sometimes.

-Bill

Arkansasoffgrid

Re: What to expect ?

Thanks for the "real world info"