Can I Run My House on Solar Power Only?

Aniket Bhor in Residential Solar

In several places worldwide, solar has single-handedly powered entire communities. Therefore, yes, you can definitely run your house on solar power alone. It is the most flexible power source the world has ever seen – powering everything from pocket calculators to entire cities.

And when you consider the fact that every hour enough sunlight strikes the Earth to power the world’s population for a full year, it becomes obvious that a single house can be powered with solar. The more important question, however, is “how can I run my house on solar power only?”. Let’s find out the answer to that.

System Size

The first and probably the most important thing you will need to power your entire house with solar is proper system size. Having fewer than the required panels and your house won’t have enough power, and having more than the required size means you would be unnecessarily spending more money.

The system size is calculated through a system design. A system design takes into account your historical energy consumption and calculates the number of solar panels you will need.

You can use a solar calculator for a rough estimate of the number of solar panels you may need. This will also give you an idea about the potential savings your system will generate. Once you decide to go ahead with the preliminary system size, you can approach a reliable solar expert for a detailed, more precise system design.

However, knowing the number of solar panels is just one part of the equation. Powering your home 24 x 7 with them needs some other considerations too. Let’s take a look.

24-Hour Power

The biggest limitation of solar power is that it is available only during the day. The typical power consumption of a home, on the other hand, peaks during the evenings. This mismatch means no matter how many solar panels you use, they will be of no use after sunset – unless you choose one of the following two solutions:

Net Metering:

Net-metering allows you to send the excess energy from your solar panels into the grid during sunny hours, and use some energy from the grid during darker hours. 

Ultimately, you will be billed only if you take more energy from the grid than you give it. If your system is accurately designed, usually net-metering can result in zero or near-zero electricity bills.

(source: NL Hydro)

Battery Backup:

Sending electricity back to the grid is like handing it over to someone to safe keep for a while. But what if you do not have anyone to babysit your excess electricity? The most common way to store energy is by using batteries. 

Batteries are chemical devices that undergo a chemical reaction when charging, and when you need energy, they undergo a reverse chemical reaction that generates almost the same amount of energy you used for the first reaction. Isn’t that cool?

Both net-metering and batteries have their own pros and cons. Net-metering saves the cost of batteries, which can be a significant amount. Batteries, on the other hand, ensure energy security when the grid itself is not reliable, or worse, absent from your location.

Therefore, batteries are a favorite for remote, off-grid cabins and even in places where blackouts are common. But technology keeps evolving, and you don’t necessarily have to choose between net-metering and batteries. With the advent of better hardware and even better software, you can have system configurations wherein you can enjoy the benefits of both.

Let’s go over the types of system configurations, and how effectively they help you run your house on solar power alone.

Solar Only (net-metering only):

The most basic configuration is having grid-connected solar panels with net-metering. This allows using some solar power during the day, sending some of it back to the grid, and then using power as needed from the grid when the panels aren’t generating anything. Although simple and useful, this configuration has a couple of flaws. 

Firstly, in the event of a blackout, you cannot use power from your panels, even during sunny hours. Regulations in most places do not allow solar power systems to operate when the grid is down (also known as islanding protection), to protect any technicians from solar power flowing back into the grid.

Secondly, this option is not useful if you have no grid connection, or have an unreliable grid.

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Sunlight Backup:

Enphase, the giant in microinverters recently coined the term “sunlight backup”, which means backing up your appliances with solar power when your grid shuts down. This is a solution to islanding protection.

This option makes use of technology that severs the connection between a solar power system and the grid while keeping the connection between your solar panels and some key appliances intact. You may not power heavier appliances like ACs, but you can keep powering your phones, lights, fridge, etc. as long as the sun shines.

Home Essentials Backup:

The home essentials backup option differs from sunlight backup in the fact that it is not restricted by “sunlight” hours. In this case, you can power several appliances during the day as well as the night.

This option makes use of a battery bank, and also allows you to connect an AC generator (such as a gas generator) that turns on seamlessly when grid power goes down. This way, you can power any and every device, grid or no grid. 

Through the use of intelligent software, this option also allows you to manage which appliances you want to operate. Because let’s face it, running an AC on a generator is not a wise thing to do, unless you own an oil well.

The home essentials backup option also allows you to transmit metered energy into the grid and earn money from it, given that such programs exist in your location.

Full Energy Independence:

The last, and ultimate system configuration is full energy independence, which, as the name suggests, does not need grid support at all. With sufficient solar panels, a full-fledged battery bank, and possibly an AC generator, your system is capable of powering through the worst and longest of blackouts, and even without a grid at all.

Such a system offers all the benefits of the previous three configurations and goes beyond that. This configuration is the most expensive among all four, but it also saves the highest amount of money over its lifespan – which is a whopping three decades or more.

Here’s a table that gives an overview of all four system configurations:

Frequently Asked Questions 

How many kW do i need to run my house?

The size of a solar power system needed to power your whole house depends on your consumption, your home’s location, and its orientation. However, on average, most homes need anywhere between 5 kW and 10 kW to power everything inside.

How many solar panels do I need to power a house?

As mentioned in the previous answer, anywhere between 5 and 10 kW is needed to power a whole house. In terms of the number of solar panels, roughly three panels make a kW, so 15-30 solar panels are needed to power a house.

How long can a house run on solar power alone?

As long as you have clear sunlight falling on a correctly designed solar power system, your house can run continuously on solar panels. However, if the weather is overcast, your system may generate less power. Also, if your consumption increases say by adding in a new electric vehicle, then the available solar panels may not be sufficient.

Conclusion

Solar power is a magnificent source of energy. The sun powers everything on our planet, and it can definitely power a single house. To do that, you only need to ensure you have a correctly sized and properly installed system.

The intermittency of solar did not allow homes to be powered effectively and efficiently through nights or darker days in the past. However, with modern batteries and smart technologies, customers can choose from several types of backup systems that ensure that a part or the whole house can run on solar power alone. 

Ultimately, it is your choice how you want to power your appliances, and how much reliance you want on the grid and solar power. Whatever option you choose, either way, choosing solar is a win in itself!

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