Off Grid System Installation

Published by firstgreen on

We are going to create a sample project for off grid solar system in this article. We are going to run 1 LCD TV for 8 hours in one day of the week for the off grid solar system project.

We are looking to design an off-grid solar PV system for which we will be considering the following:

TELEVISION 1 80 Watt 2 Hours 7 Day 14 Hours
LIGHTS 7 9 Watt 5 Hours 7  Day 35 Hours
CEILING FANS 4 45 Watt 8 Hours 7  Day 56 Hours 13,375 W

All the above devices add up to a value of 12,925 W of electricity usage.
We cannot simply assume this figure as there are always losses to account for with the electricity generation. Therefore, we multiply this figure with 1.2 giving us 16,050.

Battery Capacity Calculation.


We calculate the weekly battery capacity with the following formula;

( ACt x 1,2 + DCt ) / Battery Voltage = AH / Week

(16,050  watt) / 24 Volts = 668 AH / Week

We have preferred the battery voltage as 24 volts for our solar energy system.


Now we have found our weekly battery current, so how much daily amperage we need? We calculate this with the following formula;

(AH / Week) / 7 = AH / Day

As a result of the formula, we find out that we need daily 95 Ah battery.

Similarly batteries have a certain loss in certain operating temperatures and none of the batteries are used until to the end. This is why we are going to multiply the battery capacity with 1,50.

95 Ah x 1,50 = 142.5 Ah.

Given the above figure, we will opt for a 150AH battery.

Solar Panel Power

We are going to prefer polycrystalline solar panels in our off grid solar system project. Because it is easier to supply and it is cheaper when compared to the monocrystalline solar panel.

We will be considering a 380W,PolyCrystalline ReneSola Panel that produces 9.94 Ah current per hour.

Our off grid solar system was intended for 8 months. Well, what is the daily sunshine period during this 8-month period? We are going to calculate it as 6 hours per day average since monsoon season is accounted for in this period.

Therefore, In 6 hours, it produces 59.64 Ah current (6 x 9.94Ah).

As total battery capacity is 150 Ah, our battery will be fully charged in about 2,5 days (150 Ah / 59 Ah = 2.5 days).


Battery Charge Controller


Following should be considered while choosing a battery charge controller device for a off grid solar system.

  • What is the voltage of the battery connection?
  • What is the voltage of the solar panel connection?

Since our solar panel provides 9.94 Ah per hour, we will opt for a 10 Ah power device.
In this case, we take a Luminous solar charge controller – 10 amp

In the case that we have two solar panels arrange parallelly , 2 x 9.94 Ah = 19.88 Ah. In this case, you should prefer a 20 Ah charge device.


Inverter Calculation


We have to prefer an inverter in line with how much watt power output we want per hour. Our AC output power per hour is 323 W in our electricity generation with the solar energy system. This means that 330-watt Luminous Solar inverter will be enough for us.

. Inverter voltage will be 12 volts because our battery connection is 12 volts.

The above calculations allow for a successful solar PV system setup.