HOW TO CALCULATE THE SIZE OF SOLAR SYSTEM YOU NEED FOR YOUR HOME/OFFICES.
From GHS Solar Education 101, you already know that a complete solar system is connected thus:
SOLAR PANELS > CHARGE CONTROLLERS > BATTERY > INVERTERS > LOAD (HOME)
To understand how to size the solar system we have to understand the following parts: Every appliance in your house/office has a particular amount of energy it uses for operating and this Power is rated in watts.
LOAD is simply an add up of your home appliances rated power. If you have 10 bulbs, 1 laptop, 2 standing fans, 2 TVs, 1 fridge, 1 blender and 1 air Conditioner (1.2Hp), your total load will be the table below:
Total Load = 100 + 75 + 160 + 240 + 200 + 300 + 1000 = 2075 Watts.
1000 watts (W) is equal to 1 Kilowatt (1kW) or lkVA approximately.
Total Load = 2075 Watts or 2.075kW (2.075kVA)
Now that we know the total load of the house/office where this solar system will be installed, we can now pick the INVERTER capacity. INVERTER CAPACITY: Inverters are rated in Kilowatts or kVA, we have (1.5kVA, 2kVA, 2.5kVA, 3kVA, 3.5kVA etc.). For an Inverter to power the load efficiently, we will need to purchase an Inverter with power higher than our load power.
For the load above, we need to purchase an Inverter of 2500 watts (2.5kW/2.5kVA) or higher. With the Inverter capacity sorted, we will need to determine what battery capacity will be required to store up energy for the required hours we will want to operate these appliances using solar energy.
BATTERY: Batteries are rated in kWh (Kilowatt hour). This simply means your battery capacity will be determined by number of hours you want to draw energy/current from it before the stored power/current in it is exhausted. If we want to power our load above constantly on the solar system for an approximate of 8hours, the battery capacity can be determined multiplying the total load by 8hours:
2.075kW x 8hours = 16.6kWh
You will need a total battery bank of 16.6kWh.
Now that we know the battery bank capacity that is required to keep our home appliances constantly for approximately 8hours, we need to determine the capacity of SOLAR PANEL ARRAY that will refill this battery bank in a good time.
SOLAR PANELS: The approximate hours of sunshine in our region NIGERIA is 5 hours. We a solar panel array that can recharge this battery bank above in 5 hours or less while still powering our house load during charge time. Solar panels are rated in watts and we have panels of 200, 250, 400, 500, 540 and 650 watts etc.
To refill a battery bank of 16.6kWH in 5hours of sunshine, we will need a total solar panel power of:
16.6kWH / 5hours = 3.32kW plus an additional 2.075kW of panel to run our load and at the same time charge the battery.
Recall that 1000watts = lkW 3.32kW + 2.075kW = 5.395kW We will need a solar panel array of 5.395kW or 5395watts. Using a 200Watt panel, you will need 5395/250 = 21.5 panels Using a 400Watt panel, you will need 5395/400 = 13.4 panels.
Using a 540Watt panel, you will need 5395/540 = 9.9 panels
The last component to select the size is the CHARGE CONTROLLER and it is rated in Amperes (Amps).
Charge Controller size is calculated as total Solar array power divided by the Voltage of your battery bank (non•technicians can get this from the battery manufacturer) basically we have 12volts, 24volts, 48volts or 96volts battery irrespective of the battery size.
In our case study above, we are using a 48volts battery with total capacity of 16.6kWh Total solar panel array power = 5395 Watts Solar Charge Controller capacity = 5395/48 = 112.3 Amps We can buy any Charge Controller higher than the capacity 112.3Amps
A Charge Controller of 120Amps is sufficient for this Solar System.
We hope you have gotten a general idea of how to choose the sizes of your Solar system components. There are a few technical aspects to this topic that are not discussed here. If you would like further information or technical aspect of this guide. Feel free to contact us on any of our social media handles or on WhatsApp with the phone number in the footnote.
Thank You.
