khalidusman: Sizing breakers for my off grid system

Welcome to the forum Khalidusman,

I have copied your "comment" from your "wall"... Nobody really watches the walls--You need to created a new discussion (thread) and everyone will see it and have a chance to respond.

I believe you are in Pakistan--So I do not know your electrical code and components vs what we use here in North America.

Looking at your high voltage Solar array--They are all in series (8x 450 Watt panels in series). And your charge controller can take upwards of ~500 or 600 volts Vpanel max input.

Need details about the Vmp/Voc/Imp/Isc (voltage maximum power, voltage open circuit, current maximum power, current short circuit) for the solar panels (and, in theory, the maximum series protection fuse from the panel specifications).

Can you give us a link to the hardware (inverter/charger/solar charger/etc.)?

Also--Regarding your loads--A 1,000 Watts for how many hours per day?

I suggest understanding your loads (Watt*Hours per day), size the battery bank to support those loads (typically 25% discharge for two day, to 50% state of charge --- Or ~4x daily load is nice).

And then there is sizing the array for your battery bank, loads, and hours of sun per day... Something like this:

http://www.solarelectricityhandbook.com/solar-irradiance.html

Sargodha Pakistan
Average Solar Insolation figures

Measured in kWh/m2/day onto a solar panel set at a 58° angle from vertical:
(For best year-round performance)

Jan	Feb	Mar	Apr	May	Jun
4.75	5.45	5.77	6.20	6.47	6.22
Jul	Aug	Sep	Oct	Nov	Dec
5.39	5.33	5.55	5.88	5.40	4.73

With circuit breakers and fuses... There are 3 major specifications. The maximum current (like 5,000 Amps dead shorting battery bank), Maximum voltage (around 30 volts for a 24 volt battery bank--Note that AC vs DC voltage ratings are usually different). And the trip current...

In North America, typically our breakers and fuses are designed to trip at 100% current (can be minutes or hours), and not trip at 80% load. For systems that have a long period of steady current (like 5 hours charging a battery bank), I suggest that you take the "working current" such as 50 amps from battery bank @ 24 volts:

• 50 amps * 1/0.80 (or x 1.25) = 62.6 --- Round up to next standard size (70 or 80 amps)

Remember that fuses/breakers are there to protect your wiring from catching fire--So, if you use an 80 amp fuse/breaker, the wiring should be rated for 80 amps too.

-Bill