2024: How to Size a Solar Power System for Your House

When it comes to setting up a solar power system in Nigeria, one of the first questions that comes to mind is, How much power do I need?

This is where solar system sizing comes in. Essentially, it’s about ensuring your solar panels, inverter, and batteries can generate enough electricity to meet your energy requirements.

Think of your solar system as a recipe: if you don’t have the right amount of ingredients (energy output), you won’t get the result you want (a reliable power supply).

Sizing your solar system correctly means balancing your energy consumption and your system’s energy production.

In this guide, I’ll walk you through everything you need to know about sizing a solar system in Nigeria, whether you’re powering your home, business, or a new property development.

We’ll break it down into easy-to-follow steps so you can confidently make informed decisions.

The first thing you need to do is understand how much energy your household uses. If you’re like most Nigerians, you’re probably running fans, air conditioners, refrigerators, and lights, and perhaps charging a few electronics.

Here’s how to calculate your energy use:

• Look at your electricity bill: It shows your total monthly usage in kilowatt-hours (kWh).
• Calculate daily consumption: If your bill says you use 300 kWh in a month, divide that by 30 days. That gives you 10 kWh per day.

Solar systems are not 100% efficient. Factors like dust, heat, and shading from nearby trees or buildings can reduce how much energy your panels produce.

Most solar panels operate at about 75-85% efficiency. So, if your daily energy requirement is 10 kWh, plan to generate about 12-13 kWh per day to cover these losses.

Now that you know your daily energy needs, it’s time to figure out how many solar panels you’ll need to meet those requirements.

The amount of sunlight (or solar irradiance) your house gets every day affects this calculation.

In Nigeria, we get about 4-6 hours of peak sunlight per day, depending on where your houses are located.

Example Calculation:

Let’s say you need to generate 12 kWh per day. If you get 5 hours of peak sunlight, divide 12 kWh by 5 hours. You’ll need about 2.4 kW worth of solar panels.
If each panel produces 350 watts, you’ll need about 7-8 panels.

Solar panels only generate electricity when the sun is shining. To keep your home powered at night or during a rainy day, you’ll need battery storage.

How much battery capacity do you need?

• Battery capacity (kWh) = Daily energy usage × Number of backup hours needed

For example, if you want enough backup for 12 hours and your daily usage is 10 kWh, you’ll need 5-6 kWh of battery storage.

Popular Battery Options in Nigeria:

• Lithium-ion batteries: More expensive but last longer and are more efficient.
• Lead-acid batteries: Cheaper upfront but require more maintenance.

The inverter is like the brain of your solar system, converting the DC power from the solar panels into AC power that your appliances use. To size your inverter:

Match Your Consumption: The inverter’s wattage should be equal to or slightly higher than your total energy consumption at any given time.

For instance, if you are running appliances that consume 5,000W at peak usage, you need at least a 5,000W inverter.

A charge controller manages the energy going from your solar panels to your batteries, ensuring they don’t overcharge (which can damage them).

There are two main types:

• PWM (Pulse Width Modulation): Good for small systems.
• MPPT (Maximum Power Point Tracking): More efficient and better for larger systems.

If your budget allows, go for MPPT controllers – they’ll give you more energy from the same number of panels, which is a big win!

Will you be adding more appliances later, like a bigger air conditioner, extra lights, or another fridge? If so, it’s smart to oversize your system slightly.

Adding 10-20% more capacity will help you avoid the hassle of upgrading your system later.

Nigeria’s climate plays a huge role in solar system sizing. The northern part of Nigeria gets more sunlight compared to southern regions, which means homes in the north might need fewer panels to generate the same amount of energy.

In Lagos, for example, you can expect about 4-5 hours of peak sunlight, while places like Kano might get 5-6 hours.

Knowing your location’s sunlight availability helps in accurately sizing your system.

If you run a business, your energy needs are higher than in a typical home. You’ll need to:

• Look at your peak energy demand – when your business uses the most energy.
• Size your system to ensure critical operations (like refrigeration, computers, or lighting) don’t get interrupted.

Business owners should aim for a larger battery capacity and possibly more panels to ensure their operations aren’t disrupted during working hours.

Are you a property developer incorporating solar into new constructions? Offering homes with solar power can make your properties more attractive, especially in Nigeria where stable power is a luxury.

When sizing solar systems for new builds:

• Anticipate future needs: Modern appliances and electronics are energy-intensive.
• Ensure each unit is equipped with enough panels, batteries, and inverters to meet potential buyers’ expectations.

• Maximize Sunlight: Ensure your panels are installed where they get the most direct sunlight.
• Energy Conservation: Reduce your energy needs by using energy-efficient appliances.
• Regular Maintenance: Keep your panels clean and free of dust to maintain their efficiency.

Sizing your solar system correctly is key to maximizing your investment and ensuring reliable, cost-effective energy for years to come.

Whether you’re powering a home, business, or property development, taking the time to calculate your energy needs, choose the right components, and maintain your system will pay off in the long run.

FAQs on Solar System Sizing

1. How many solar panels do I need for my home?

It depends on your daily energy usage and the amount of sunlight your area receives. For example, if you consume 10kWh per day and receive 5 hours of sunlight, you’ll need around 7-8 panels of 300W each.

2. Can I add more panels to my system later?

Yes, most solar systems are designed to be expandable. If you plan for future growth, you can add more panels, batteries, or even a larger inverter down the line.

3. How long will my solar batteries last?

Solar batteries can last between 5-15 years depending on their type and how often they are used. Regular maintenance and avoiding deep discharges can help extend their lifespan.

4. What happens if I undersize my system?

If your system is too small, you won’t generate enough power to meet your needs, forcing you to rely on the grid or a generator more often. This can defeat the purpose of going solar.

5. Do I need a backup generator?

In Nigeria, having a backup generator can be helpful, especially during rainy seasons or prolonged outages. However, a well-sized solar system with sufficient battery storage can reduce the need for a generator.