How to Calculate the Installed Capacity of Your Solar System

How to Calculate the Installed Capacity of Your Home Solar System

Transitioning to solar power is an environmentally conscious and economically prudent choice. Nevertheless, figuring out the precise installation capacity for your home solar power system can be quite difficult. This guide will take you through the necessary steps to determine the optimal capacity for your photovoltaic system, maximizing your investment.

Step 1: Determine Your Energy Consumption

Prior to initiating your solar adventure, it is essential to comprehend your typical energy usage. You can locate this information on your utility bill or by performing an energy audit. The objective is to calculate the energy output you desire from your solar power system, with the aim of meeting a substantial portion, if not the entirety, of your household electricity requirements. Remember to consider any future electricity needs, like installing more air conditioning or charging electric vehicles.

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Average Monthly Energy Usage:  450 kWh Units

Provision for Future Electricity Demand increase:  +100 kWh Units

Total Required Energy per month:  550 kWh Units

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Step 2: Calculate the required system capacity

The amount of sunlight available differs depending on the geographical location and the time of year. Determine the average number of hours of sunlight your region receives to calculate the potential energy output of your solar power system. This data can be accessed online or by reaching out to hayleys solar for assistance.

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Sun Hours in Your Area (per day): 3.8 hours

Estimated Daily Energy Generation per kWp: 3.8kWh Units

Required System Capacity:  550 kWh / 30 days /3.8kWh  = 4.82 kW Units

Recommended System Capacity:  5 kW Units

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Step 3: Calculate the Number of Panels

Once you have determined the capacity required, divide this by the capacity of each panel. For example, if you calculate the capacity as 5kW and each panel has a capacity of 500W, you will need 10 panels. Make sure you consider the specifications of the panel you choose, as this will affect the entire installation.

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Panel Capacity: 500W each

Number of Panels Needed:  5000W (5 kW) / 500W = 10 panels

Recommended Number of Panels:  10 panels

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Step 4: Assessing Your Roof Space

Assessing the available roof space is an essential step in determining the maximum capacity of your solar power system. Start by determining the size of the unshaded portion on your roof where solar panels can be installed optimally. Unlike other areas, Sri Lanka, situated near the equator, benefits from consistent solar energy production regardless of the panel orientation. Although the recommended panel orientation is south-facing, it's crucial to take into account the roof's angle, as it can affect the efficiency of energy production. In our nation, the standard guideline for roof inclination is around 10 degrees, guaranteeing that the majority of sunlight is effectively harnessed.

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Size of a Single Panel Approx: 28 sq.ft

Installable Panel Quantity: 10 Panels

Required Roof Space: 28 * 10 = 280 sq.ft

Steps to Calculate

1. Determine the Power Consumption of the AC:

   • Look at the AC unit’s specifications to find out its power rating (in watts or kW).
   • Calculate the total energy needed to run the AC for the duration it will be used at night (in kilowatt-hours, kWh).

2. Calculate the Energy Requirement:

   • If the AC runs for 8 hours at night and consumes 1.5 kW, the total energy required is:
     $$\text{Energy Required} = \text{Power Consumption} \times \text{Hours of Operation}$$$$\text{Energy Required} = 1.5 \, \text{kW} \times 8 \, \text{hours} = 12 \, \text{kWh}$$

3. Determine Battery Storage Needs:

   • To store 12 kWh of energy, you need batteries with a combined capacity of at least 12 kWh. Considering efficiency losses, you might need batteries with a total capacity of around 15 kWh (assuming 80% efficiency).

4. Calculate Solar Panel Requirements:

   • The number of solar panels depends on the daily energy generation needed and the average peak sunlight hours.
   • If you need to generate 15 kWh to cover the AC and efficiency losses, and you have 5 peak sunlight hours per day, the required power generation capacity is:
     $$\text{Required Power} = \frac{\text{Energy Required}}{\text{Peak Sunlight Hours}}$$$$\text{Required Power} = \frac{15 \, \text{kWh}}{5 \, \text{hours}} = 3 \, \text{kW}$$

5. Determine the Number of Panels:

• If each solar panel generates around 300 watts (0.3 kW), the number of panels needed is:
  $$\text{Number of Panels} = \frac{\text{Required Power}}{\text{Power per Panel}}$$$$\text{Number of Panels} = \frac{3 \, \text{kW}}{0.3 \, \text{kW/panel}} = 10 \, \text{panels}$$

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