How Many Solar Panels Are Needed to Power a House?

As every home has a different energy requirement, it is important to know how much kilowatt is required to address your home energy needs before finalising the number of solar panels you will need. Whether you want your rooftop solar system to meet 100% or some proportion of your home’s electricity demand, the decision will require you to define your objective of going solar first. Most people generally switch to solar to reduce their electricity bills while lowering their carbon footprint. 

To understand how many solar panels are needed to power your house, you need to analyse your average annual energy requirements, your current electricity usage in watts, and peak Sun hours in your region. Also, the efficiency and physical size of the solar panels you are considering can influence your home’s total count of solar panels in the rooftop solar system. 

Determine How Many Solar Panels Are Needed to Run a House

To calculate how many solar panels are needed to run your house you need to know the energy requirements of your house. This calculation involves three key factors. It’s true that the easiest way could be to ask a reputed solar company in India to perform a complete solar inspection and walk you through all the aspects of upgrading to solar so that you can make an informed decision. However, you can still do the math yourself by obtaining enough information. The basic formula is to divide the total solar system size by the production ratio and then by individual panel wattage.

You need to consider three main factors to get a near-accurate estimate of how much kilowatt is required for your home’s electricity demand:

• Annual electricity usage
• Solar panel wattage
• Production ratios

Annual Electricity Usage

The first step to assessing how many solar panels are needed to power your house will require you to check the current electricity usage for a year. This information, measured in kilowatt-hours (kWh), can be easily found in your monthly electricity bills. Your annual electricity usage should factor in all areas of electricity consumption, such as all types of small and large appliances, lights, ACs, geysers, laptops, TVs and any motors. For the explanatory purpose, we will assume a household with an average electricity consumption of 6,000 kWh annually.

Solar Panel Wattage

All solar panels look and function alike, but they are not created to generate equal amounts of power. That’s why you must find out the home solar panels’ wattage before making a decision. The panel wattage represents each panel’s electricity production capacity. The standard range for solar panels wattage is between 250 to 400 watts. Depending on your energy requirements and budget, you can pick above or below the average panel wattage of 300 watts.

Production Ratios

The production ratio of a solar panel system is the correlation of its estimated energy output (in kWh measured over time) to its actual size (in W). This might appear to be a 1:1 ratio as it’s easy to believe that a system will always perform and generate power to its total capacity. However, fluctuations arise depending on the amount of Sunshine falling on your home. As a result, the ratio varies.

For instance, a 10kW system that generates 16kWh of electricity annually will have a production ratio of 1.6. The regions with long days and ample Sunshine will see a better production ratio than those with much rainfall and fewer hours of Sunshine.

The Formula for Finding How Many Solar Panels are Required for Home

Now that you have the required information handy, put the figures in the following mathematical formula to determine how many kWs are required to power your household. 

Number of panels = system size/production ratio/panel wattage

Now, if we put the figures we have estimated so far, the number of panels can be calculated as 6,000 kWh / 1.6 / 300 W. This equates to 10 to 15 solar panels that are enough to power a medium-sized home. So, now you can put your house’s unique values to determine how much kw is required for your house. 

A Different Way of Finding Estimated Solar Use

If you don’t prefer this approach to finding how many solar panels you need to fulfil your electricity demand, a simpler way would be to evaluate your monthly utility bills. They tell you how much energy you are consuming. Now multiply the energy usage figure by the total number of strong sunlight hours your intended solar installation location receives. Divide the figure thus obtained by the wattage of the panels you are planning to buy.

Factors Affecting How Much Kilowatt Required for Home

Although the above calculations will give you a near-accurate estimate of how much kW is required for your house in India, there might still be more to think about. Here are some of the factors that can influence the number of solar panels for your intended location.

System Efficiency

Even the most efficient solar panels can’t do the job of absorbing Sunshine and generating energy at their top capacity levels at all times of the year. Many weather conditions hinder the working of solar panels. On days when sunshine hours are reduced due to rainfall, a cloudy sky, or winter, these are the days when you’ll need a few additional panels to be able to generate just enough energy your home needs. Hence, experienced solar panel installers are likely to add an additional 25% more over the standard number of solar panels needed in your rooftop solar system.

Hours of Sunlight

Clearly, solar panels require an uninterrupted supply of Sunshine to generate ample amounts of energy. Hence, you must determine the amount of Sunshine you get every day. If sunshine hours are less in your region due to weather or geographical conditions, you’ll need more panels to increase the amount of Sunshine captured in a day by your solar panels.

The Wattage of Your Panels

As discussed earlier, the wattage of solar panels varies from 250 to 400 watts per panel. If you choose to install lower wattage panels, you would need a higher number of panels to generate ample power to meet your home’s energy requirement. Of course, this depends on whether you are aiming for 100% conversion of your energy usage to solar energy. However, if you only hope for a partial conversion, then you wouldn’t mind settling for fewer panels of low wattage.

Cost

After the question of how many solar panels are needed to run a house, you would certainly be concerned to learn about the prices. Before you decide what solar panels to pick, it’s important to evaluate your budget and how much you are willing to spend on your home solar systems.

Does Solar System Type Affect How Much Solar Panels I Need for my Home?

Rooftop solar panel systems are available in three different options: on-grid, off-grid and hybrid systems.

On-grid solar systems are the type of solar power framework that is tied to the grid and can transfer solar electricity to the government. The only key components making up this type of system are solar panels and the solar inverter. A grid-tied network is the simplest and most budget-friendly type of home solar system as you don’t have to buy any additional solar panels.

On the other hand, off-grid or stand-alone solar system owners are required to go for a lot more solar panels. This is because the type of solar system is responsible for generating enough electricity to meet day-to-day demands and charging solar batteries, which is an important component in this type of solar system.

A hybrid solar system is connected to the grid and has solar batteries to keep your home powered during an outage. For this system, the solar developer will recommend adding the maximum number of solar panels to meet your electricity requirements.

FAQs

Will I continue to get an electricity bill after switching to solar?

Once you have added solar panels to your rooftop and enjoy green solar energy, the generation of a monthly electricity bill will continue as long as you are connected to the grid. However, you can expect a reduced/zero or even a positive solar credit balance if your electricity exports to the grid exceed any electricity imports for the month. 

Is it possible to increase the solar system size after installation?

It’s always possible for homeowners to add more solar panels and increase the size of their home solar system if the current system size falls short of their home electricity requirements. This will help them further reduce the cost of electricity and unveil the great solar benefits for your home.

What is solar panel efficiency?

The efficiency rating of different solar panels represents the amount of Sunshine that solar panels absorb and turn into usable electricity. A higher efficiency rating means you’ll need fewer solar panels to generate ample energy with fewer panels. For example, the 15% efficiency rating of solar panels means that 15% of Sunshine that hits the solar panels will be used to generate electricity.

Are solar panels costly?

In a rooftop solar system, solar panels are the most costly component that holds the highest share of the overall upfront cost of home solar systems in India. However, the cost of solar panels can vary depending on the energy efficiency rating of solar panels.

I need a 24 hours electricity supply. How much kW is required for my house?

Solar production is intermittent for the simple fact that the Sun doesn’t shine around the clock. As a result, solar electricity isn’t available at night. Luckily, the problem can be easily resolved by adding solar batteries that can consistently maintain enough reserve of solar energy for later use. 

Are solar panels worth it?

Given the current environmental crises, solar is certainly the only way forward. However, the individual decision to adopt solar will depend on your electricity prices, daily energy usage and your desire to choose an environmentally-friendly energy source. Considering all these factors in combination with your home’s geographic location can show you how favourable solar panel installation will be for you.

How long does it take for solar panels to pay for themselves?

Despite the high upfront solar investment, modern solar panels, in most cases, have a commendable pay-off of 6 to 8 years while reducing the cost of electricity for your home for the rest of the 25 years of lifespan of solar panels.

How much do solar panels weight?

Depending on how many solar panels are needed to power a house, installing solar panels will add additional weight to the roof. There are several options for homeowners to design a unique mounting structure for their panels creatively. Hence, it is important that you ensure the integrity of the roof so that it can bear the burden of solar panels for the next 25+ years.

Do solar panels require a lot of maintenance?

Maintaining solar panels is much easier as the structure doesn’t have any moving parts, which eliminates the chances of any functioning failure. In addition, with the right panel cleaning routine, you can maintain the efficient functioning of solar panels and prolong their life.

Is my roof suitable for solar panel installation? 

Depending on how many solar panels are needed to run your house, you will need ample space free of any shade cast by neighbouring trees or buildings to install solar panels. Shade hinders the solar panel’s ability to absorb Sunshine and efficiently lowers energy output. Even a small shaded area on one panel can bring down the efficiency of all the interconnected panels.