Calculate the Number of Panels for a Load without Battery Backup

How to Calculate the Number of Panels for a Load without Battery Backup? . Solar energy is a clean, renewable resource that’s becoming increasingly popular. However, designing a solar system without battery backup requires careful planning to ensure your load demands are met efficiently. This guide simplifies the process by breaking down the calculations step-by-step.

Why Skip Battery Backup?

Battery backup systems provide energy storage for nighttime or cloudy conditions but can significantly increase the cost of a solar installation. For those looking to power loads during daylight hours, a battery-free system is a cost-effective alternative.

Benefits of No Battery Backup

• Reduced system cost
• Simplified installation
• Lower maintenance requirements

Read More : Types of Solar Panels and Which Solar Panel Type is Best?

How to Calculate the Number of Solar Panels to Run a Specific Load without Battery Backup

If you need to calculate the number of solar panels for an appliance like an air conditioner, water pump, or fan to run during the day without battery backup, this article will help. It provides step-by-step calculations to determine how much power your solar panels will produce at different times of the day. This step-by-step guide will help you find out how many solar panels you need to run your electrical device during the day, especially without battery backup power.

Tips : This calculation is based only for running a load purely on solar panels without using a battery backup.

Read More : How to Wire Solar Panels in Series-Parallel Configuration?

How Many Watts Does My Solar Panel Produce Based on Sunshine During the Day?

This question is frequently asked: how many panels are needed for an AC without a battery? Let’s learn how to design it today. But first, we need to understand some facts about solar panels, which are as follows:

1. Solar panels produce their rated power (the wattage written on their nameplate) only when sunlight falls directly perpendicular on them. The output efficiency of the solar panel is highest during this time period. This happens only for a short time around noon when the sunlight is at its peak.

If $W$ is the power output in watts written on the solar panel, the actual power produced will depend on the angle at which sunlight hits the panel. Hence, if we need to determine the power a panel will produce at a specific time, the formula will be:

P = W × sin ⁡(θ)

Where;

• P is the power produced by the panel,
• $W$ is the power written on the panel,
• $\theta$ is the angle of sunlight on the panel.

2. Another factor is atmospheric pollution, such as light clouds, which can reduce production.

3. The third factor is the panel getting heated by sunlight, reducing production when the temperature exceeds 50°C.

5. Fourth, it is impossible to keep the panel clean all the time, which reduces production.

5. Lastly, as the solar panel ages, its production decreases. On average, production decreases by 1% per year.

Read More : How Many Panels Batteries Charge Controller and Inverter Need ?

Due to reasons two, three, and four, in areas where sunshine for roughly 10 hours a day, even in summer, solar panels produce on average only 80% of the written power. If clouds are dense, production can drop below 80%. The given calculations assume minimal clouds, allowing visibility of the sun. You can also see this fact in the graph below, indicated by the red arrow on the curve.

This means that if we want to determine the power a solar panel will produce at different times of the day in summer, it will be 80% of the power calculated using the above formula:

Let’s now use this formula to calculate the power a 550-watt panel will produce from 8 AM to 8 PM:

• At 8 AM: very minimal
• At 8:30 AM, angle 9 degrees, thus:

• At 9 AM, angle 18 degrees, power:

Read More : The Effects of Specific Weather Conditions on Solar Panels

Similarly,

Avoid these pitfalls to ensure accurate sizing:

• Ignoring losses in the system
• Overestimating sunlight hours
• Using outdated or inaccurate panel specifications

Practical Example of Solar Panel Sizing

Scenario Overview

A small office requires 10 kWh/day, located in an area with 5 peak sun hours.

Step-by-Step Calculation

1. Daily Energy Need: 10 kWh
2. Panel Wattage: 350 W
3. Peak Sun Hours: 5 hours

Calculation:

Number of Panels = 10,000 Wh / (350 W × 5) = 5.71 panels

Rounding up, six panels are needed, with an additional 10% buffer for losses.

Read More : How to Wire a Three-Phase Meter?

Benefits of a Battery-Free System

By avoiding batteries, you:

• Save on upfront and replacement costs.
• Simplify system design and reduce weight.
• Focus solely on daytime energy needs.

Real-Life Applications of Solar Without Batteries

Battery-free solar systems are ideal for:

• Agricultural irrigation during daylight.
• Powering industrial equipment in sunny climates.
• Outdoor lighting and security systems.

Read More : How to Wire Lights in Series?

FAQs About Solar Panel Sizing Without Battery Backup

Q1: Can I add batteries to my system later?

Yes, many solar systems are designed to accommodate battery additions in the future.

Q2: What happens on cloudy days?

Energy production decreases but doesn’t stop entirely. Plan for variability in sunlight.

Q3: How do I calculate panel efficiency losses?

Estimate 10–20% losses for wiring, inverters, and dirt accumulation on panels.

Q4: Are higher-wattage panels better?

Higher-wattage panels reduce the total number required but may be more expensive.

Q5: Can I use this method for off-grid systems?

Yes, but ensure you account for all energy needs during peak sun hours only.

Related Topics

• How Many Panels Batteries Charge Controller and Inverter Need ?

• The Effects of Specific Weather Conditions on Solar Panels

• Can You Run Solar Panels Without an Inverter? Discover the Truth and Power Behind Solar Energy!

• Smart WiFi Circuit Breakers

• Voltage Source Inverter vs. Current Source Inverter

• What Is a Smart Grid? Everything You Need to Know

• Design a Solar Photovoltaic Powered DC Water Pump

• Determine the Right Size Capacity of a Subpanel