olar panel (PV) is a device which can convert energy from light energy (proton) to electrical energy. Each panel is rated by its DC output power. Currently the best commercial solar panel (PV) efficiency is around 17.4%. Solar panels are normally 12V DC output. In large solar panel 24V or 48V DC output also seen.
A technical specification (backside of a solar panel) given below.
Normally a few common specification are seen all types of solar panel
Like Nominal voltage, Maximum Voltage, Open circuit Voltage, Maximum Current, Short Circuit Current, Maximum System Voltage, and Maximum Power.
Maximum Power: it means it can deliver maximum 20 Watts electricity. If we need total 100 Watts then we need to setup 5 panel in parallel or series (depend on design).
Maximum Voltage: it means its maximum output voltage is 17.6V
To calculate the solar system we have to measure
Inverter (for AC output)
Open Circuit Voltage: It means the voltage without load. It is sometimes given the symbol Voc
Maximum Current: It means the maximum output current.
Short Circuit Current: It means the current of short circuit of solar panel.
Maximum System Voltage: It means that, when we connect solar panel in series then maximum voltage limit is 600V so we could connect (600/17)=35 solar panel in series.
Now if a subscriber wants to setup a solar system for 2 bulbs and 1 fan. (12 volt DC)
(1 bulb=10 watt, 1 fan=20 watt) then the total load
2 bulb (10×2) = 20 watt
1 fan = 20 watt
Total = 40 watt
Now if he wants 4 hours back up time.
Then total load (4hour × 40watt) = 160 (watt per hour)
To measure the battery ampere for the above load.
Volt = 12
Battery is needed 12 volt, 14 AH.
Now to calculate the solar panel:
Generally a battery charging current = 10% of its AH
Charging current = 1.4 A ()
Solar panel needed = 1.4 A 12 V
= 16.8 watt
So recommended the charge controller is 12 Volt, 1.4 Amp
Thus a solar system is calculated
(System loss is not added with this measurement, so approximate 25% system loss will be added.)