How Many Solar Panels Do I Need for 2,000 kWh per Month?
For homes with high electricity usage that rely entirely on solar energy, it's crucial to size your system correctly and purchase the right number of solar panels to meet your needs. Unfortunately, there's no simple answer— the number of panels required depends on several factors such as panel wattage, your system's location, panel angle, and more.
Specifically, if you're wondering how many solar panels are needed to produce 2,000 kWh per month, this can vary from 25 to 65 panels. If you live in California and use highly efficient panels, you might need around 25 panels. In contrast, if you live in Washington and use less efficient panels, you might need closer to 65 panels. In this article, we'll explain how to determine where you fall within this range.
Calculate Number of Panels Based on Kilowatt-Hours and Sun Hours
The number of solar panels required depends on several factors, with location being one of the most significant due to the variation in Global Irradiation (GI), also known as sunlight, by region.
You're likely familiar with kilowatt-hours (kWh) — the unit used to measure electrical energy. One kWh equals 1,000 watt-hours (Wh).
Solar panel systems are typically measured in kilowatts (kW), which represents the rate at which electricity flows, or electrical power.
You can calculate kWh if you know the wattage of a device using this equation:
Electrical energy (kWh) = Electrical power (kW) x hours
If you're unsure about your daily power consumption, you can use our off-grid solar system calculator to estimate the electrical load your appliances require.
Solar panels are labeled with their wattage, making it straightforward to determine the electrical energy they produce over time. For example, a 350 W (0.35 kW) solar panel operating for ten hours would generate 3.5 kWh of energy.
A quick refresher on Peak Sun Hours:
Peak sun hours measure the solar irradiance received in a location. Solar panels typically require 1,000 W/m² to produce their full wattage. Since this level of irradiance isn't constant throughout the day or in all areas, we calculate peak sun hours to assess how well solar panels will perform.
To calculate peak sun hours, multiply the solar irradiance by the hours it's received. For instance, if an area receives 600 W/m² of solar irradiance over five hours, it gets 3,000 Wh/m² (3.0 kWh/m²) of sunlight, or three peak sun hours. You can find your area's peak sun hours using the Global Solar Atlas.
To determine how much energy solar panels can produce, multiply their wattage by their peak sun hours. For example, 3 kW of solar panels in an area with three peak sun hours could produce 9 kWh of electricity.
Calculating the number of solar panels:
To calculate the exact number of solar panels needed, we use a model from the Global Solar Atlas developed by Solargis. For this equation, you'll need your desired monthly kWh, your location's specific photovoltaic power output (PVOUT), the power output of a single panel, and the average number of days in a month (30.4).
of solar panels = [(Desired monthly kWh ÷ 30.4) ÷ PVOUT] ÷ kW of one solar panel
For example, let's say you want to generate 2,000 kWh per month in San Francisco using 370 W (0.37 kW) panels. First, identify San Francisco's daily PVOUT from the Global Solar Atlas.
Now, with the variables:
Desired monthly kWh = 2,000 kWh
PVOUT = 4.776 kWh/kWp per day
Individual panel power = 0.37 kW
Here's the equation:
of solar panels = [(2,000 kWh ÷ 30.4) ÷ 4.776 kWh/kWp] ÷ 0.37 kW
of solar panels = (65.79 ÷ 4.776 kWh/kWp) ÷ 0.37 kW
of solar panels = 13.78 ÷ 0.37 kW
of solar panels = 37.24, rounded up to 38 solar panels
As you can see, several factors determine the number of solar panels needed to generate a specific amount of energy. Higher panel efficiency or a location with a higher PVOUT can reduce the number of panels needed to achieve your desired output.
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