When considering the switch to solar energy, one of the most crucial steps is sizing your system correctly. Solar system sizing is the process of determining the right capacity to meet your energy needs while considering factors like location, energy consumption, and future expansion. In this post, we’ll walk you through the basics of solar system sizing and design, helping you make informed decisions that maximize your solar investment.
What is a Solar PV system?
A Solar Photovoltaic (PV) System is a renewable energy technology that converts sunlight directly into electricity using solar panels made of photovoltaic cells.
Key Components of a Solar PV System
- Solar Panels (PV Modules): These are made up of many photovoltaic cells. The cells capture sunlight and convert it into electricity.
- Solar Charge Controller: Its primary function is to regulate the voltage and current flowing from the solar panels to the batteries.
- Inverter: The inverter converts the direct current (DC) electricity produced by the solar panels into alternating current (AC) electricity, which is the standard type of electricity used in homes and businesses.
- Battery Storage: Batteries are used to store excess energy produced during the day, which can be used at night or during cloudy days when solar production is low
How to Size a Solar PV System
1. Assess Energy Requirements
The initial step in designing a solar PV system is to calculate the total power and daily energy consumption of all the loads to be connected to the system, as shown in table below.
2. Solar Panel Sizing
The total daily energy consumption is 23000Wh. Total PV Energy Required (Wh) = Total Daily Energy Consumption x Efficiency Factor
A 25% margin is a good amount to account for inefficiencies.
= 23000 x 1.25
= 28750Wh
Total PV Power (W) = Total PV Energy Required / Peak Sunshine Hours
Assuming the peak sunshine hours for our location is 3.5 hours.
Total PV power = 28750/3.5
= 8214.29Wp
Number of Solar Panels Required = Total PV Power/Rated Output Power of Selected PV Module
Using 480W PV module,
Number of solar panels required = 8214.29/480
= 17.11 units.
This can be rounded off to 18 solar panels.
Therefore, the system should be powered by at least 18 units of 480W PV module
3. Inverter Sizing
The total load power is 3400W.
Inverter Capacity = Total Load Power x Safety Factor
With a safety factor of 25%,
Inverter Capacity = 3400/1.25
= 4250W
The required inverter capacity is approximately 5000W.
4. Battery Sizing
Total Battery Capacity (Ah) = (Total Energy Consumption x Days of Autonomy) / (Depth of
Discharge x Battery Efficiency x Nominal Battery Voltage)
Where,
Days of Autonomy = 1
Depth of Discharge = 80%
Battery Efficiency = 85%
Nominal Battery Voltage = 48V (Lithium-ion battery)
Total Battery Capacity (Ah) = (23000 x 1) / (0.8 x 0.85 x 48)
=704.65Ah
With capacity (Ah) of each battery being 200Ah,
Number of Batteries Required = 704.65/200
= 3.5 ≅ 4 batterie
5) Charge Controller Sizing
Charge Controller Rating = Total PV Power / Battery Bank Voltage
= 8214.29/48
= 171.13A
The rating of the charge controller should be at least 200A.
Achieving an efficient and cost-effective solar system hinges on proper sizing. By carefully considering your energy usage and choosing the right components, you’ll optimize your system for long-term performance. This step-by-step guide empowers you to make informed decisions, helping you achieve a reliable and solar energy solution that is tailored to your needs.