solar system design

[Mike90250]

i want to design a off grid solar system to run a load of 450W.

Watts without time, well, it was guessed at the load being on always. 24 hours a day.

Like the old math problem, if 2 trains are travelling toward each other, one at 12 mph and the other at 38 mph, how far apart are they after 10 minutes ?

we have to guess at the missing part.

[greenHouse]

Skipped right over it and missed it.

You didn't miss much -- I suspect he's wrong, as you can see from the required battery size!

[Sunking]

Sunking, He gave you the load -- 450 watts.

Skipped right over it and missed it.

[greenHouse]

Sunking,

He gave you the load -- 450 watts. I doubt he means 450 watts continuous, but that's the load he gave.

450 watts * 24 = 10,800 watt-hours AC per day.
Derate by 55%, 10.8 KWh / 0.55 = 19.6 KWh DC per day.

Two days autonomy = 39.2KWh to 50% DoD, 39.2 / 0.50 = 78.4KWh total. That's the battery bank size.

Assume 48 volt inverters.

78.4KWh / 48 volts =~ 1,600Ah

Now for the array, assuming 2.5 hours minimum winter insolation (just 'cuz and he didn't say ...)

19,200 watt-hours / 2.5 hours = 7,680 watts.

Panels are 270 watts each, 29 panels needed. They are high Voc panels, so unless he lives somewhere that is always warm, that's 15 strings of 2 to stay below the common 150Voc limit. Don't know about the gear he spec'd and ain't lookin' 'cuz he ain't payin'.

30 * 270 = 8,100 watts.

Back calculate the peak charging current at 57.6 volts for start-of-absorb --

8100 watts / 57.6 volts = 140 amps

Now for rate of charge --

1600 / 140 = C / 11.4, which is plenty fine.

Enjoy!

[Sunking]

All you have given is the size of the size of the panel. None of your questions can be answered with that info. First thing we need to know is how many watt hours per day, and load demand calculations...

Second you cannot getaway with only 2-day autonomy, that would wear your batteries out in a very short time.

[vikas maurya]

i want to design a off grid solar system to run a load of 450W.
the tech specs of module i want to use is as follows

Power (W) ------------------------ 270 W
Max. Power Voltage (V)------------- 36.72
Max. Power Current (A)------------- 7.45
VOC Voltage (V)-------------------- 44.49
SC Current (A)---------------------- 7.95

Please suggest me
1.battery size (for 2 days autonomy)
2.charge controller size ( using Steca germany products)
3.inverter size ( using studer germany products)
4.Number of modules in parallel and series
5.what would be the PV plant size

i already designed this system but i feel every time i do some minor mistake which make my system oversize........
So need inputs from experts......
Thanks