10
Amps Hours:
30.51 Amp Hours per Day
Assumption:
Solar panel is exposed to 6 hours of suitable sunlight each day.
The required current from the system would be 30.51 Amp Hours/6 Hours = 5.09 A.
The required watts of the system would be:
5.09A×17.2V÷0.8=110W (17.2V --- Module Vmp, 0.8 --- Power Consumption Factor)
In this example a 110 Watt panel is required to run the appliances for the desired time.
How much battery capacity is required?
Solar power systems are generally sized to give plenty of reserve (autonomy) from the
battery or battery bank.
Battery Capacity Calculation:
Current (Amps) x Hours = Amp Hours (Ah).
In the example above we have determined we required 30.51 Ah per day.
It is not good to run a battery all the way down to zero during each charge cycle as it severely
shortens the battery life. It is good practice to leave at least 50% charge in the battery. For
the example above, we need at least 30.51 Ah / 0.7 = 43.6 Ah. (0.7 or 30% is added in to the
equation to account for losses due to resistance and other system inefficiencies). If a typical
100 Ah, deep cycle, RV/Marine battery is used, this equates to about 43.6% depletion daily
and is adequate in this example.
9. Frequently Asked Questions
How does the solar panel work?
The solar panel converts sunlight energy into DC electric power & can be used to charge a
rechargeable battery.
How many solar panels will it take to run my appliances?
As a general rule the user should establish the amps required to run the appliances & multiply
them by the expected module voltage.
Power Calculations:
Amp Hours (Ah) = Current (Amps) x Working Time (Hours)
Module Power (W) = Current (Amps) x Expected module voltage (V)
After completing these calculations the capacity of the solar panels can be established.
Example:
The following table represents a typical portable appliance configuration.
Appliance
12V Fluorescent Light
Hours
Amp Hours
Amps
Watts
12V B&W Television
12V Radio
12V Fan
12V Travel Iron
12V Fridge
Estimated Consumption
8
20
5
4
120
45
12
12
12
12
12
12
4
1
1
5
1/6
6
2.6
1.67
0.45
1.65
1.67
22.5
30.51
Voltage
0.67
1.67
0.42
0.33
10
3.75
