April 28, 2025 / Solar Panel

How to Calculate the Right Solar System Size for Your Needs — And Estimate Installation Space

When you start considering a switch to solar, one of the first questions that comes up is: “What size solar system do I actually need?” Whether you’re planning an off-grid setup for total energy independence or an on-grid system to cut your electricity bills, getting the size right is crucial for both efficiency and cost-effectiveness.

At Eastman, we’ve simplified this process with our user-friendly Load Calculators, so you can skip complex manual math and plan your solar system smarter and faster.

Sizing an Off-Grid Solar System

An off-grid solar system powers your home or business independently from the utility grid. This means your system must cover your daily energy consumption and provide enough backup for days when sunlight is limited.

For example, if you want to power a weekend home using Eastman’s solar panels and solar batteries, you’ll first calculate your daily watt-hour requirement, factor in peak loads for high-powered appliances, and decide on autonomy days—typically 2–3 days of battery backup. With our durable deep cycle lead-acid batteries, you can ensure reliable storage capacity for your energy needs.

If manual calculations aren’t your thing, you can simply use our Load Calculator to get precise recommendations in minutes.

Sizing an On-Grid Solar System

On-grid systems are directly connected to the utility grid and are generally easier to size. For instance, if you run a small business in Gurugram and want to install Eastman’s high-efficiency solar panels and an Eastman on-grid inverter, you’ll start by reviewing your annual electricity usage, checking local peak sun hours, applying a derate factor, and calculating the number of panels needed.

Again, you don’t have to crunch the numbers yourself—our On-Grid Load Calculator will do the work for you, ensuring you get a system tailored to your needs.

Planning Installation Space

Once you know your system size, the next step is planning for installation space. As a rule of thumb, a 1 kW solar setup typically requires 80–100 square feet of shadow-free rooftop space. By choosing Eastman’s compact solar modules, you can maximize efficiency even if your available space is limited.

Final Thoughts

Sizing your solar system doesn’t have to be overwhelming. Whether you’re planning an off-grid installation or connecting to the grid, Eastman’s Load Calculators make it easy to design a system that fits your lifestyle and energy goals.

With our wide range of solar panels, inverters, and batteries, you’re always equipped with reliable solutions backed by years of industry expertise. Explore our Load Calculators to get started and bring your solar plans to life—the smart way.