What is the difference between a Kilowatt and a Kilowatt-hour? Or Understanding the Difference Between Kilowatts and Kilowatt-hours for Rooftop Solar

If you’re considering installing a rooftop solar system, you’ll likely come across the terms “kilowatt” and “kilowatt-hour.” These terms can be confusing, but understanding their meaning is important for designing and installing a solar system that meets your energy needs. In this article, we’ll explain the difference between kilowatts and kilowatt-hours and how they relate to rooftop solar systems.

Kilowatts (kW) and Power

First, let’s define a kilowatt (kW). A kilowatt is a measure of power, which is the rate at which energy is produced or consumed at a given moment. Power is measured in watts (W), and one kilowatt is equal to 1,000 watts. Kilowatts are often used to describe the capacity of an energy generation system, such as a rooftop solar system.

For example, a 5 kW solar system has a capacity to produce 5,000 watts of power at any given moment. This means that the solar panels on the system can generate up to 5,000 watts of electricity under ideal conditions. However, the amount of energy the system can generate over time is determined by a different unit of measurement: kilowatt-hours.

Kilowatt-hours (kWh) and Energy

A kilowatt-hour (kWh) is a unit of energy, which is the amount of power consumed or produced over a period of time. One kilowatt-hour is equal to 1,000 watt-hours, and it represents the amount of energy used or generated by a 1,000-watt device over the course of one hour.

For example, if you left a 100-watt light bulb on for 10 hours, it would use 1 kilowatt-hour of energy (100 watts x 10 hours = 1,000 watt-hours = 1 kWh). Kilowatt-hours are often used to measure the amount of energy a household consumes over a billing period, such as a month.

Calculating Kilowatt-hours

To calculate how many kilowatt-hours a solar system can produce, you’ll need to know the system’s capacity (in kilowatts) and its efficiency. Efficiency is a measure of how much of the energy that hits the solar panels is converted into electricity. A higher efficiency means that more of the energy is converted into electricity, which means more energy is produced for the same amount of sunlight.

To calculate the number of kilowatt-hours a solar system can produce, you’ll need to multiply the system’s capacity (in kilowatts) by the number of hours of sunlight per day and the system’s efficiency. For example, a 5 kW system with an efficiency of 20.5% in an area that gets 5 hours of sunlight per day would produce:

5 kW x 5 hours x 0.205 = 5.12 kWh per day

This means that the system would produce 5.12 kilowatt-hours of energy per day, on average.

When designing a rooftop solar system, it’s important to consider the amount of energy you’ll need to power your home over the course of a day, week, month, or year. The amount of energy you consume will depend on a number of factors, including the size of your home, the number of appliances and electronics you use, and your energy usage habits.

By understanding the difference between kilowatts and kilowatt-hours, you can make informed decisions about the size and capacity of your rooftop solar system. A larger solar system with a higher capacity (in kilowatts) can produce more energy, but it will also cost more to install. On the other hand, a smaller system with a lower capacity may not meet your energy needs, which could result in having to purchase energy from your utility company.

Additionally, understanding your energy usage habits can help you design a solar system that maximizes your energy savings. For example, if you typically use the most energy in the evening, you may want to consider installing a battery storage system that can store excess energy generated during the day for use at night.

In summary, a kilowatt is a unit of power, which measures the rate at which energy is produced or consumed at a given moment. A kilowatt-hour is a unit of energy, which measures the amount of power consumed or produced over a period of time. Understanding the difference between these two units is important for designing and installing a rooftop solar system that meets your energy needs.

Think of it this way: a kilowatt is like the speed of a car, while a kilowatt-hour is like the distance the car travels. Just as a car’s speed can change from moment to moment, the amount of power your solar system produces can vary throughout the day. However, the amount of energy your system produces over time is what determines how much you’ll save on your energy bill.

When considering a rooftop solar system, it’s important to evaluate your energy usage habits and the size of your home to determine the appropriate system capacity. By understanding the energy output of a solar system, you can make informed decisions about how to best utilize the energy produced and maximize your energy savings.

At Delphi Sun, our professional designers are ready to analyze your energy usage and home characteristics to give you the most optimal design which will maximize your overall savings. Our team’s focus is on giving the best design that will be in your best interest. Many solar sales reps will design and build a system that will optimize their commission and not you which is why our design professionals do not get paid a commission, they are incentivized to provide you the best experience possible and answer all of your questions to ensure you are comfortable and confident with your purchase. Our mission is to revolutionize the way people access clean energy by providing a seamless, transparent, and affordable online buying experience. We hope you enjoy working with us as much as we enjoy helping you take back control of your energy!