How Many Solar Panels Are Needed To Power A House?

Tim Hamlin
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Solar Energy Boom & Benefits

Solar energy is not only having a boom in popularity, but it is also one of the most exciting, innovative, and exciting new technologies on the market right now.

In some of the sunniest areas of the country, families have the satisfaction of powering their homes and other small scale applications from a single solar panel system.

Even more families are discovering how solar power can save a lot of money on energy bills.

After the initial investment of buying the solar kit, you'll start saving money with every quarterly or monthly energy bill you receive. As the cost of solar power continues to drop, more and more people are discovering the benefits of solar energy.

For homes in the right climates, solar power can be a better choice than energy generated by coal, nuclear or even renewable energy sources. With advancements in solar technology, this is becoming more and more popular around the world.

Solar panels are becoming much more refined, integrated, and easier to install than ever before.

But as the solar industry begins to grow, there are a lot of skeptics who still think solar power cannot compete in today's world of energy.

These know-it-all's are of the mindset that solar power is just a fad and that it is only viable in small amounts. This sedentary mindset is creating a problem for our country, who should be focused on utilizing renewable energy as much as possible.

Calculating the Number of Solar Panels Needed to Power a House

One of the most common questions people ask about solar power is, “How many solar panels do I need?”

The typical answer is that it depends on several variables: the climate, the roof orientation, the latitude, the shading, etc.

Energy-Efficient Appliances

Many people looking to get solar panels installed on their homes start with how many solar panels do I need to run my house. This is a very common question, but the best answer is to instead look at the appliances in your home.

Energy-efficient appliances and appliances that have been rated for energy-efficiency will actually be much easier on solar panels and require less energy for the work. Instead of opting for big screen tvs and other energy-consuming items, choose energy-efficient appliances and you will have more efficient solar panels when you need these appliances to run.

The most energy-efficient part of your home is the appliances you use most often. This means all of the smaller appliances like refrigerators, washers, and dryers will need the exact amount of energy just to work properly. In addition, if you care about this portion of your home being energy-efficient, you should consider looking into solar panels now that can be used to power these appliances instead of plugging them in.

The size of your panels is going to really depend on all of these appliances. From how many are used to the wattage they use. For instance, your refrigerator will need an average of 800 watts to run. While your washer will require an average of 850 watts and your television will use an average of 325.

How Does Solar Energy Work?

Solar power is a renewable energy source that comes from direct sunlight and is stored for later use. It is an emissions free, clean energy. In essence, it is harnessed from where it is created, the sun, and put to work for us here on earth. The sun pours approximately 1,366 watts of energy onto each square foot of the Earth. Since there are about 2.5 billion square feet of land in the US, there is nearly 5 trillion watts of energy available to be harnessed.

To put that into perspective, the average US household uses about 11,000 watts per hour. Each square foot of solar panels can generate about 150 watts each hour. So, if you had about 1 square foot of solar panels on your roof, it would generate as much energy for your house as one light bulb.

For this reason, standard solar panels are 28 inches by 28 inches and about an inch thick. The average US home uses an average of 30,000-50,000 kWh of electricity each year. A 5 kWh solar system will produce approximately 900 kilowatt hours of power in a year, effectively cutting the average energy bill in half.

For reference, solar panels are measured in watts, kilowatts, and megawatts. 1 kilowatt is equal to 1,000 watts, a megawatt is equal to 1,000 kilowatts, and a gigawatt is equal to 1,000 megawatts.

On-Grid Versus Off-Grid

The very first thing to decide is whether or not you want to be connected to the electric grid. If you do, you’ll need to find out how much power you’ll be using at peak times and what power sources are available.

If you don’t want to be connected to the grid, you have a choice between solar-only systems or hybrid systems that also provide backup power from batteries and/or the grid.

Once you have your power needs (and backup power sources) in mind, you can start thinking about what you’ll need to fulfill them and how you’ll get it. The good news is that solar power systems are getting better and more efficient every day. They’re often cheaper than traditional power sources, despite still being a luxury item for many people.

There many solar power installation calculators and they typically require you to have an approximate understanding of at least some of the components of a solar power installation.
To effectively use one, you should understand what equipment you have and what you need to provide power to each piece of equipment you are powering!

What follow are only examples of items to be included in your calculations!

Electrical load:

This generally includes all items you want to power with solar including:


Analysis of Solar Power Needs

Below we will be putting together an example of what you would need based on three different variables. These three different variables include the daily power consumption, the efficiency of the solar panels and the amount of days you get heavy sun.

For the sake of this example, we're going to assume your daily power consumption is 1200 watts. Based on this, you would need to have 4X 180W panels, or 2X 270W panels. These watt ratings were taken from the Hanwha 270W270 system, which is a popular choice from the supplier in Australia, Sunline.

The second variable is the efficiency of your solar panels. If you were to put 4X 180W panels, you could expect about 170 watts of actual power generated. This doesn't include the efficiency loss of the panels such as the trickle charge maintenance available from your inverter and controller.

Now for the third variable, this is what we call the days of heavy sun. For example, you're not just looking at getting 300 watts of power per day, but its increase will be between 4-5 times the regular days. In this case, we can have anywhere between 450-600 watts of power per day.

If you were to get 2X 270W panels, you can expect about 300 watts of power generated per day. If you add in the high efficiency of the panels you can expect an additional 60 watts of power generated while the sun is in full swing.

Cost & Efficiency

Solar power is one of the cleanest energy sources available and is rapidly becoming an important part of the renewable energy sector. Solar power systems delivered a record 10GW of electricity to UK homes in 2013, compared to 5GW in 2012, representing nearly one third of all new electricity generating capacity installed in the country.

The cost of installing a solar system varies depending on a variety of factors, including your geographic location, the type of system you are installing and the size of your home. In the UK, most installations typically range from around £1500 to £5000. The average cost is around £3000.

It is possible to buy solar panels for as little as £1 per watt on some occasions, but this is often with a long waiting list and you will be unlikely to get the final product within a couple of days or, more likely, a couple of weeks.

Solar power is not only clean but also very cost effective when compared with other energy sources. On average the typical UK household will spend around £2000 per year on gas and electricity, which is at least 20% less when powered with solar panels.

Solar panels are generally measured in terms of peak power (in Wp), which is the theoretical maximum output in full sunlight. The actual power produced, depending on weather, ground conditions and the type of device consuming the power, is somewhat less.

How Much Energy Does a Solar Panel Produce?

When thinking of solar panels, our minds immediately go to the area of a solar panel and how much energy will be produced. This is, of course, important to know as you need to know how much energy you need to produce.

So what, and how much, do you need to know about what can be produced?

The ability for our solar panels to produce energy is measured by watts (Wp). This is the amount of power that the solar panels can produce when exposed to sunlight.

The size of a solar panel is measured by the solar cells that it contains and the amount of surface area on it.

A solar panel uses a group of photovoltaic solar cells to produce energy. These are cells that are sensitive to light and solid-state material that turns light that is captured into an electric current.

There are a few different types of cells today and each may have slightly different surfaces and thicknesses.

The type of cell used in a solar panel will determine how much energy it is able to produce.

You need to be familiar with the area of your solar panels and their wattage rating so that you can see how much energy you need to produce during the entire year.

You can do this by calculating the size of your solar panels multiplied by their wattage per square foot.

Final Thoughts

In short, 10kW of solar power is capable of producing 10,000 watts of electricity each hour, for every hour of the year. We have compiled reputable guides that answer the questions: How many solar panels are needed to power a house?

If you ever find yourself in a situation where you need to know how many solar panels you would need to power your home, I hope you have found this guide helpful.