Sizing Your Solar System: A Step-by-Step Guide for Homeowners

One of the most common questions we get at KRATOX is, "How big of a system do I need?" Sizing a solar power system correctly is the key to meeting your energy goals and ensuring a good return on investment. A system that's too small will leave you frustrated and still reliant on the grid or generator. A system that's too large is an unnecessary expense. This guide will walk you through the key steps to finding that 'just right' size.

Step 1: The Energy Audit - Know Your Consumption

Before you can produce, you must know what you consume. The first and most critical step is to conduct an energy audit. This involves listing every appliance you intend to power with the solar system.

• List Your Appliances: Go room by room and list everything: lights, fans, TVs, fridges, ACs, water pumps, laptops, etc.
• Find the Wattage: For each appliance, find its power consumption in watts (W). This is usually on a sticker on the device or in its manual.
• Estimate Daily Use: Estimate how many hours per day you use each appliance.
• Calculate Daily Energy (Wh): For each appliance, multiply its wattage by the hours of use to get Watt-hours (Wh). For example, a 100W TV used for 5 hours is 500Wh.
• Sum It Up: Add up the Wh for all appliances to get your total daily energy consumption. Divide by 1000 to get kilowatt-hours (kWh). This is your target daily production number.

Step 2: Sizing Your Solar Panel Array

Your solar panels need to generate enough power to meet your daily kWh needs. In Nigeria, we typically get about 4-5 "peak sun hours" per day on average. This is a conservative estimate that accounts for weather.

The Formula: (Total Daily Energy in Wh) / (Peak Sun Hours) = Required Solar Array Size in Watts (Wp).

Example: If you need 10,000Wh (10kWh) per day: 10,000Wh / 4.5 hours = ~2,222 Wp. You would need a solar array of about 2.2kWp. This could be achieved with six 400W panels (2,400Wp), giving you a healthy buffer.

Step 3: Sizing Your Inverter

The inverter must be able to handle the maximum load you might run at any single moment. This is your "peak load."

• Add up the wattage of all appliances you might realistically run at the same time.
• Choose an inverter with a continuous power rating at least 25% higher than your peak load to handle startup surges from motors (like in ACs and fridges).

Step 4: Sizing Your Battery Bank

Your batteries must store enough energy to power your home through the night and during cloudy days. This is called "days of autonomy."

The Formula: (Total Daily Energy in Wh) / (Battery Voltage * Depth of Discharge) = Required Battery Capacity in Amp-hours (Ah).

We typically design for 1-2 days of autonomy. The Depth of Discharge (DoD) is crucial – for lithium-ion, we use 0.8 (80%), while for lead-acid, we use 0.5 (50%) to preserve battery life.

Let the Experts Help

While this guide gives you a good understanding, accurate sizing requires professional expertise. The KRATOX team uses specialized software and deep experience to conduct a precise energy audit and design a perfectly balanced system for your specific needs, ensuring optimal performance and the best value for your investment.