To determine exactly how many solar panels you would need to offset 2000 kWh of monthly energy consumption, you need an estimate of the average amount of sunlight that you receive in your location.

In this article, I’ll explain how this works and show you how to estimate the number of solar panels that you need.

## How many solar panels do I need for 2000 kWh per month?

2000 kWh of monthly energy consumption translates to about 66 kWh of daily energy consumption. To offset 100% of this energy consumption, the solar panels you install have to produce 66 kWh daily and 2000kWh each month.

**A solar energy system that could produce 2000 kWh per month, would consist of anywhere between 27 and 66 standard residential solar panels. The amount of solar power, or the number of solar panels that you need, will mainly depend on your location. **

For example, while a person in Colorado Springs, CO would require 34 residential solar panels that are rated at 330 watts each, a person in Columbus, OH would require about 44 of the same solar panels to produce 2000 kWh of energy per month (on average).

**However, on average, a system that could produce 2000 kWh per month, would be rated at 13 kW. This roughly translates to 40 (330W) solar panels.**

To estimate the size of the system that you need, and how many solar panels such a system consists of, **you’ll need an estimate of the average amount of sunlight that you receive each day**. The term for this is **Peak Sun Hours**.

Before I explain what Peak Sun Hours are and how this works, please note that:

**kWh**stands for**kilo-Watt-hours (1000 Watt-hours)**and is the**unit for measuring electrical****energy**.**kW stands for kilo-Watts (1000 Watts)**and is the**unit for measuring electrical power**, which is the rate at which energy is being transferred. Solar installations are rated in kW.

The relationship between energy and power is the following:

**Electrical Energy (kWh)** = **Electrical Power (kW)** x **Time (hours)**

For example, if an air conditioner uses exactly 1 kW (1000 Watts) of power for 8 hours, it will have consumed 8 kWh (8000 Watt-hours) of energy by the end of those 8 hours:

**Electrical Energy (kWh)** = **Electrical Power (kW)** x **Time (hours)**

**Electrical Energy (kWh)** = **1 kW** x **8 hours**

**Electrical Energy (kWh)** = **8 kWh**

If a solar panel produces exactly 300 watts of power (0.3 kW) for 5 hours, it will have generated 1.5 kWh (1500 Watt-hours) of energy by the end of those 5 hours:

**Electrical Energy (kWh)** = **Electrical Power (kW)** x **Time (hours)**

**Electrical Energy (kWh)** = **0.3 kW** x **5 hours**

**Electrical Energy (kWh)** = **1.5 kWh**

Now that we’ve covered the basics, let’s see how Peak Sun Hours can help you get an estimate.

**What is Peak Sun Hours?**

The amount of sunlight that an area receives is quantifiable and is referred to as **Solar Irradiance**. **The standard unit for measuring Solar Irradiance is W/m² (Watts per Square Meter)**.

The higher the Solar irradiance the higher the power output of the solar panels. In fact, solar panels need exactly **1000W/m²** of solar irradiance **to produce 100% of their rated output**.

For example, in order for a 300W solar panel to produce 300 Watts of power at a certain moment, the solar irradiance needs to be 1000W/m² at that moment.

But as mentioned above, watts represent power, what we’re looking for is energy, which brings us to **Peak Sun Hours**.

**Peak Sun Hours measure the amount of energy per area that a certain location receives from the sun, over a certain period of time. **Let me explain**.**

For example, if a certain location theoretically receives exactly 800W/m² of solar irradiance for 7 hours, this location will have received 5600Wh/m² (5.6 kWh/m²) of energy from the sun by the end of those 7 hours. The same location could be said to have received 5.6 Peak Sun Hours.

Now, let’s say we had 1 kW of solar power installed in that location, we can calculate the amount of energy that our solar panels would have produced by the end of those 7 hours:

**Energy Production (kWh)** = **Solar Power Rating (kW)** x **Peak Sun Hours**

**Energy Production (kWh)** = **1 kW** x **5.6 Peak Sun Hours**

**Energy Production (kWh)** = **5.6 kWh**

So, logically, if you know the average number of Peak Sun Hours that you receive on a daily basis, and you know the amount of daily energy consumption that you need to offset, you can calculate the amount of solar power that you need:

**Required Solar Power Rating (kW)** = **Average daily Energy Consumption (kWh)** ÷ **Daily peak Sun Hours**

Since 2000 kWh per month equates to about 66 kWh per day, the next step is to determine the average daily peak sun hours that you get.

### How many Peak Sun Hours do you get per day?

The **PVWatts Calculator** from the **National Renewable Energy Laboratory (NREL)** is a free tool that estimates the average Peak Sun Hours that a location receives each day.

Based on your address, the tool will provide the annual and monthly averages of the Peak Sun Hours that you receive on a daily basis.

As an example, I submitted Tuscon, AZ as the address, and the calculator provided the following table:

On the second column of the table, you can see that the calculator provides values with this unit: kWh/m²/day. 1 kWh/m²/day is equivalent to 1 Peak Sun Hour per day.

The tool estimates that the city receives **6.54 Peak Sun Hours per day on average **(annual average). In other words, the tool estimates that the city of Tuscon, AZ receives – on average – 6.54 kWh/m² of sunlight energy per day.

It is also important to note that the tool assumes that your solar panels will be installed on a roof section that:

- Faces south (Azimuth angle = 180 deg)
- Has a 20-degree tilt (4-5/12 roof pitch)

However, these default values can easily be corrected in the System Info section of the calculator.

**Azimuth and tilt angles will influence the results, so make sure to submit the correct information.**

Once you determine how many peak sun hours you receive in your location, you can use the following calculator.

## Solar panels kWh calculator:

The following calculator estimates the number of solar panels that you need, based on your monthly energy consumption and the average number of peak sun hours that you get each day.

I used the value from the example above (6.54 Peak Sun Hours), and here are the results:

The calculator estimates that a home in Tuscon, AZ, with an average energy consumption of 2000 kWh per month, requires a 10.2 kW system to offset 100% of this energy consumption. Such a system would consist of approximately 32 residential solar panels.

Please note that the average residential solar panel is rated at 330 Watts. To learn more about residential solar panels, please refer to this article.

The article in the link provides information about different residential solar panels, their wattage, sizes, etc…

We are a group of volunteers and starting a new scheme in our community. Your web site provided us with valuable information to work on. You have done a formidable activity and our whole community can be thankful to you.

Thanks for sharing! Very informative and helpful