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How To Use Solar Panels During Power Outages

Are you looking for energy reliability? Solar panels can be the answer! Learn everything you need to know about solar panels and power outages.

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Carlos Huerta
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Solar panels are among the best alternative energy sources. They are reliable, cheap, and easy to install. Many homeowners have different types of solar panels, but most of them share one major problem: solar panels shut down during power outages. If you do not know how to use solar panels during power outage, the answer is quite simple: you need to install an energy backup system that provides your home with energy independence for the duration of the power outage.

When solar panels do not have an energy backup system, they cannot work when disconnected from the grid due to several reasons. In this article, we analyze the different solar systems, explain why panels shut down during power outages, and we provide you with the best solution to this problem.

Why Solar Panels Do Not Work During Power Outages?

Power outages used to be extremely rare, but they have been regularly increasing due to major events. From 2017 to 2019, power outages increased when compared to 2013 – 2016. In 2020, U.S. electricity customers experienced an even higher increase in power outages when compared to 2019.

Figure 1: Hours of annual electric power interruptions – US EIA Annual Electric Power Industry Report

During these power outages grid-tied solar systems, are shut-down. This is a regulation that utilities set in place due to several electrical security and stability reasons:

Frequency Stability

The need for frequency regulation is one of the major reasons why grid-tied solar systems do not operate without the grid. Grid-tied inverters are unable to generate their own 60Hz or 50Hz frequency required for most electrical equipment nowadays. Instead, they are designed to synchronize to the frequency provided by the grid which has a much higher stability due to the inertia of power systems.

Security

Whenever a power outage occurs, the utility shuts power down in the distribution circuits associated to the area where the fault occurred in order for workers to approach to the area and fix the problem. If a solar power system is connected to the grid during this corrective maintenance procedure, it could be injecting power into the grid and feeding the circuits that are being repaired by the utility personnel, representing a potential electrical hazard for these workers.  

This is the reason why as a requirement for connection to the grid, the grid-tied inverters are designed to automatically disconnect as soon as there is a power outage or blackout from the grid.

What Solar System Should I Install to Have Energy During Outages?

If you want your solar panels working in case of a power outage, the only solution is to add a battery system. For this, there are two options: Installing an off-grid solar system or a battery-based solar system. Here is how these systems work.

Off-Grid Solar System

Off-grid solar systems are ideal for living in remote places or locations with no grid infrastructure. Since these aforementioned locations do not have access to electricity, the best option is to have a solar panel installation that includes the modules and a solar battery bank.

Homes with an off grid solar system work disconnected from the grid, therefore power outages do not affect them at all. These systems operate by generating power during the day and storing that excess energy on the battery backup system. At nights, when the solar panels are not generating, the home is powered with energy coming from the batteries.

Since there is no grid connection, there is also no electrical bill, which is one of the best ways to achieve zero net energy homes. The downside of these systems is that you need to have a large solar array and large battery bank to have enough capacity to power your home for several days, even with unfavorable weather.

Battery-Based Solar System (or Grid-Tied With Battery Backup)

A battery-based solar system is similar to off-grid solar systems, but they differ in the fact that they are connected to the grid, in most cases, these systems have a Smart Home Battery system like the Tesla Powerwall or LG Chem RESU, which can operate with the grid or without it. The battery-based solar system is ideal for homeowners looking to be energy independent without being entirely disconnected from the grid, providing a reliable way to ensure electrical stability for the home during power outages.

In a battery-based PV system solar panels generate energy during the day, but in this case, you decide how much energy goes back to the grid and how much is stored at your batteries. At night, when the panels are not generating, you can either use power from your batteries or from the grid.  If the batteries are charged, the excess energy will be sent to the grid and will be measured by the utility meter.

Which One Is the Best Solar System for Your Home?

Whether you end up choosing an off-grid, battery-backed, or grid-tied solar system, depends on what you are looking to achieve and the needs of your home. In this section, we compare the different solar systems, so you can pick the best option for your home.

Off-grid solar systemBattery-based solar systemGrid-tied solar system
Energy SourceUses energy coming from the solar panels directly or from the batteries.Uses energy from the solar panels, the batteries, or the grid.uses energy from the grid or the solar panels (except during power outages)
Utility Bill$0 electricity billCan offset the electrical bill (or even make a profit by selling the excess generated energy) Can offset the electrical bill (or even make a profit by selling the excess generated energy)
Cost For The SystemVery high cost (You need to have large battery bank)High cost (you need to have a home battery system)Average cost
Overall Performance
Against Power Outages
Not affected by power outagesCan use energy from the batteries during power outages and from the grid during bad weather.Does not work during power outages
Table 1: Comparing Off-grid vs Battery-based vs Grid-Tied Solar Systems

As can be seen above, the option with best technical and economical performance against power outages is the battery-based solar system. This type of system can offset your electricity bill, increases solar self-consumption, provides protection against power outages and even

What Is the Right Battery Bank/Smart Home Battery System for Me?

To ensure power stability for your home during a power outage, it is important to choose the right battery bank or smart home battery. The main factor to consider is how many autonomy days you will have with the chosen energy backup system.

U.S. homes consume on average 893 kWh monthly, dividing that consumption over a 30 days period, you would get a daily requirement of 29.76 kWh. This means that an off-grid or battery-based solar system with a 30 kWh home battery system, would supply a whole day for the average U.S. household power consumption. Since this would increase costs considerably, most customers install a home battery system with nearly 10-15kWh capacity which should cover essential loads very well during power outages.

When choosing a smart home battery, we recommend you go for at least 2 days of autonomy, especially for off-grid systems. Homes with battery-based solar systems will be fine with 1 – 1.5 days of autonomy, being ready for power outages, natural disasters, and extremely bad weather.

Conclusion: Preparing for Power Outages

Preparing your home for power outages is relatively easy. While some homeowners reduce costs by leaving out the solar energy storage on grid-tied with battery backup, installing this energy storage system and making your home grid-tied with battery backup, is exactly what will make your system robust for any situation.

Installing an off-grid solar system might not be the most popular option in suburban areas, which is why we recommend going for a battery-backed solar system. This allows you to achieve solar self-consumption when the system is generating just fine, use grid-delivered energy in bad weather conditions and have energy availability when there is a power outage.

Choosing the right smart home battery or battery bank for your home is important. Always remember to install a backup energy storage system that delivers 1 to 2 days of autonomy, ensuring you can go through any power outage without inconveniences.

Frequently Asked Questions


What Happens if I Install a Small Battery Bank Size?

Installing a battery bank with the wrong size might result in not having enough energy to endure a power outage, especially during the night. During the day, the system might be charged back up again with the solar panels, but if your home consumes too much power from a small battery bank, you will run out of power during the night


Should I Back-up All My Appliances?

In short, no. Power outages are irregular situations where the whole area is left without power from a few hours to a day or more. Using fewer resources will ensure your smart home battery lasts longer, which is why we recommend backing up only essential loads (this does not include A/C units, heating systems, nor any high-consumption appliances).


Which States in the U.S. Are More Affected by Power Outages?

While power outages can happen anywhere due to natural disasters or faults on the power lines, there are some states which are more affected by others. According to the Power Outage website, the top 5 states that experience more power outages are California, Arkansas, Washington, Texas, and Oregon.

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Author Bio

Electrical Engineer with background in solar PV designs for residential and commercial projects as well as power systems development. Fan of renewable energy topics and projects. Technical writer for papers, articles and research in related topics to sustainability and especially solar power.

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