How many solar panels do I need for 1500 kWh per month?
To find the right number of solar panels that will generate 1,500 kWh of alternating current (AC) power per month, you need first to determine how much sunlight available in your area, and what solar power rating you will use.
What Is the Solar Energy Potential in Your Area?
The amount of energy generated by a solar panel depends mainly on the amount of sunlight that falls on them, measured in kilowatt-hours per square meter per day (kWh/m2/day).
For example, a solar panel in Phoenix, Arizona, will generate much more energy than the same panel in Portland and Seattle. This means that in Phoenix, Arizona, you will need fewer panels than you will need in Portland and Seattle to produce 1500 kWh per month.
On average, the United States gets about 4.5 kWh/m2/day or about 135 kWh/m2/month, but how much sunlight your home gets can vary quite a bit, you can use a site called Global Solar Atlas to find the right values for your location (Direct normal irradiation).
Note: the value of 4.5 kWh/m2/day is also known as Peak-sun-hours, 1 Peak Sun Hour is equivalent to 1 kWh/m2/day.
Power Rating of Solar Panels
Most residential solar panels have ratings between 250W to 450W.
A solar PV system with 400-watt solar panels will need fewer panels than one with 250-watt solar panels. However, 400-watt solar panels tend to be more expensive in terms of cost per watt.
Also using solar panels whit larger output will reduce the installation space and the solar panel's load on your rooftop.
The 370-watt rigid solar panel is a good example of a rating suited for 1500 kWh solar system.
How many solar panels does it take to produce 1500 kWh?
There are a lot of variables in this question. In order to answer it in depth, some simplifying assumptions must be made.
- you consume the same amount of electricity every day of the month, so 1500 kWh per month is equivalent to about 50 kWh of energy consumption per day.
- The system has some other energy as supplemental support because if you need 50 kWh per day directly from the solar panels, every day, regardless of the weather, you will need much more panels than if you have options for the supplemental energy
- DC to AC ratio (array to inverter) is 1
So, How many solar panels do I need for 50 kWh per day?
You have a large house or private workshop that you want to run on solar energy and you need 1500 kWh per month at a rate of 50 kWh per day and you want to know how many solar panels you will need to provide this amount of electricity.
Let us say there are 4.5 hours of sunlight per day, to produce 50 kWh of electricity per month, the size of the system can be calculated as such:
System Wattage AC = 50 kWh / 4.5 h = 11 kW AC
But does installing a 11 kW solar panels mean that you’ll be generating 11 kW of electricity? Well, actually no, there will always be some losses in the system.
In solar PV systems, solar electric panels generate DC electricity. so we need an inverter to convert DC electricity generated by solar panels to AC electricity.
- The process of converting DC to AC power is not a perfect process.
- The cumulative DC system losses of an installed solar system typically hover around 10%.
Let's take an inverter with 97% efficiency and see how many kW DC must produce to get 11 kW of AC electricity.
System Wattage DC = 11 + (11 x 10%) / 97% = 12.5 kW DC
Therefore, a person in the area receives an average of 4.5 Peak Sun Hours per day, like the city of Chicago, Illinois would need 12.5 KW of solar power to produce 1500 kWh of electricity per month. This is roughly equivalent to 34 residential solar panels.
No. of 370W solar panel = 12.5 kW / 0.370 kW = 33.7 = 34 panels
Related articles:
- How many solar panels do I need for 1000 kWh per month?
- How many solar panels do I need for 2000 kWh per month?
Determine the Size of Solar System for 1500 kWh per Month Using PVWatts Calculator
The best way to solve these types of questions is with a PVWatts calculator from the National Renewable Energy Laboratory (NREL). This allows you to access your specific location and use resource data from that area. It also allows you to add the angle of inclination of the solar panels, their direction (180 is the south, 0 is the north, 90 is the east, and 270 is the west), system losses, DC to AC ratio, and the efficiency of the inverter.
- Choose your location.
- Start by choosing 10 kW solar system.
- Change the percentage of system losses to 10% (click on loss calculator and zero both soiling and shading).
- Adjust the tilt angle.
- Determine the direction your solar panels will be facing.
- Change DC to AC ratio to 1.
- Check the results for the monthly rates, if the 10 kW system does not produce 1,500 kWh per month at least for three quarters of the year, then go back to system info and increase its size until you get the right system size for you.
Summery - How many solar panels do I need for 1500 kWh per Month?
The following table shows the number of solar panels facing south that you will need for 1500 kWh per month solar system.
Peak Sun Hours |
Typical System Size |
# of Panels_300W |
# of Panels _340W |
# of Panels_370W |
# of panels_400W |
---|---|---|---|---|---|
3.5 |
16.2 kW |
54 |
84 |
44 |
41 |
4 |
14 kW |
47 |
41 |
37 |
35 |
4.5 |
12.5 kW |
42 |
37 |
34 |
32 |
5 |
11.4 kW |
38 |
34 |
30 |
29 |
5.5 |
10.3kW |
35 |
31 |
28 |
26 |
6 |
9.4 kW |
32 |
28 |
26 |
24 |
With the solar array facing south, you will need 26 to 37 solar panels to generate 1,500kWh per month, depending on the power rating of the solar panels and how much sunlight available in your location; The higher the power rating and hours of sunlight per day the fewer panels you will need.
Note that if you need 1500 kWh per month, every month, no matter what the season, you will need much more panels than if you have options for supplemental energy when needed.