A Detailed Guide on Solar Panel Wattage: Understanding the Amount of Energy a Solar Panel Produces

One of the most crucial factors you need to consider before investing in a solar panel is the amount of energy it can produce. 

Generally, prospective solar panel customers have a target for the unit of electricity they want to produce. Some want to power small appliances, while others want the solar panel wattage to fulfil their 100% power requirements.

Whatever might be your goal, you must understand the amount of energy a solar panel can produce to install an adequate number of panels. 

This detailed guide will help you understand how much solar energy you need to run your household and what the typical output of a solar cell is.

Dive in to understand solar panel wattage and solar panel power generation like never before.

How do Solar Panels Produce Electricity?

Before straightaway taking you through the details on how to calculate solar panel output, let’s first make you understand quickly about the working of solar panels.

Solar panels are made of silicon. These panels generate electricity through the photovoltaic effect. This process requires exposure to bright sunlight.

When the sunlight hits the surface of solar panels, the sunlight particles known as photons get absorbed by the solar cells. During this process, the photons knock the electrons from their orbit. 

The collision of photons and electrons produces electrical energy, which flows to the connected wire. Further, the solar inverter converts DC power into AC power to run household appliances. 

However, the solar panel wattage and the efficiency of the panels itself is highly dependent on several external factors. Let’s take a look at these factors!

Factors Affecting Solar Panel Wattage 

The specifications of a solar panel provide necessary information about the efficiency, solar panel output voltage, warranty period, etc. 

All these factors are important for determining solar panel wattage.

Let’s understand all such factors one by one!

1. The tilt of the panels

The tilt of the solar panels plays a crucial role in determining solar panel power generation. 

The sun keeps changing its angle throughout the year; for example, it shines lower in the winter, whereas in summer, the sun’s rays fall directly on the earth’s surface. The angle changes throughout the day as well.

Therefore, it is crucial to set your solar panels at an angle that provides optimum sunlight exposure. 

The ideal scenario is when the solar panel is perpendicular to the Sun. That’s when the solar panel output is maximum. 

You can also go for solar trackers that can change the tilt of the panels. However, since the parts are movable, these panels require more maintenance. They’re usually not preferred for residential rooftop installations. 

You can choose any solar panel according to your preference but keeping them at the right angle is vital to generate a high amount of electricity

2. The direction of the panels 

The direction of placing your solar panels also plays a vital role in determining the solar panel wattage. 

The solar panel electricity generation is maximum when the solar panels are facing South. 

Since India is in the Northern hemisphere, the South direction gets the maximum sunshine. 

When the solar panels are facing South, they’re able to produce maximum electricity from 9 AM to 4 PM when the tilt angle is about 10°.

If the same panels face West, they will be able to generate maximum power between noon to 4 PM only.

If they face the East, they will be able to exploit maximum power from the Sun till noon only. 

Did you know that as you move towards the North, the ideal tilt angle changes? It should be more than 20° in the North if you want the solar panel power generation to be maximum.

3. Shadow from surrounding objects

Solar panels are connected in a series to generate high voltage during the day. 

Any partial shadow caused due to nearby objects like a tree or any other object can devoid the panels from getting direct sunlight.

Many people think that the shadow will only affect the solar panel wattage in a small area. However, in reality, the shading of a single solar cell can disrupt the electricity production of all the panels attached in a string.

Therefore, to produce the required amount of solar energy, you must evaluate your roof’s suitability by determining the chances of shadow.

4. Irradiance received 

The irradiance means the amount of sunlight a place receives on a normal day. Generally, geographical locations where the sun shines bright generate high solar energy.

However, this doesn’t mean that low temperature affects solar panel efficiency. In fact, low temperature prevents overheating of panels that might yield a better solar panel output voltage. 

Moreover, extremely cold places with snowfall have good irradiance too. If you live in such an area, you just need to carefully remove the snow from the panel surface. 

Number of Solar Panels you Need for Your Solar System

Installing a solar system is the best way to meet your power requirements without leaving carbon footprints. 

However, it is essential to determine the number of solar panels you need to power all electrical appliances.

For this, you first need to calculate the maximum power supply you need by adding up the wattage of the electrical appliances you will run with the solar panel wattage. 

Later, you need to determine the capacity of the solar panel for your house, i.e., 1KW, 2KW, 3KW, etc.

Once you have the size of the solar system you will need, divide it by the wattage of the panels. 

For example, if you’re using 400-watt solar panels to build a 4 KW (4000 watts) solar system, you will need 10 400-watt solar panels (4000 watts/ 400 watts).

You can calculate the number of panels accordingly. Keep in mind that these numbers are tentative. They largely depend upon the type of solar panels being used (mono, poly, or Bifacial).

Besides, the typical output of a solar cell is 0.5 volts to 0.6 volts.

Electricity Units a Solar System Produces

The solar panel wattage depends on multiple factors. However, if all the external factors are favourable, an efficient solar system produces a good amount of electricity to run your appliances.

According to the general rule of thumb, a 1 KW solar system produces roughly 4 units of electricity every day. 

This means in a month, you get 120 units of solar energy on average. The approximate number of units would be 1440 yearly.

By keeping this as a base unit, the following table provides information on solar panel electricity generation according to different solar system capacities:

Capacity Units/day Units/monthUnits/year
1 KW41201,440 (approximately, 1400 units)
2 KW82402,880 (approximately, 2800 units)
3 KW123604,320 (approximately, 4200 units)


Shifting your power dependency from the commercial grid to the solar system is a great step. 

However, to get the most benefit, you must determine your electricity consumption and install a system with optimum solar panel wattage. 

In addition, you need to carefully install solar panels considering all the external factors like orientation, shadow, direction, and irradiance to increase their output. 


Q. What is the best and worst direction to install solar panels?

A south-facing solar panel receives maximum sunlight throughout the day. In contrast, a north-facing panel gets limited exposure to sunlight. 

Q. How many units of power do 5 KW solar systems generate?

A 5KW solar system can produce roughly 20 units of electricity in a day. This means it produces 600 units in a month and 7,200 units in a year.

Q. Can snow affect the amount of electricity a solar system produces?

Snow is reflective, which increases the concentration of sunlight. 

You only need to remove the pile of snow from the solar panels, and the high irradiance of the cold area assists in generating the required solar panel wattage.