In recent years, homeowners have become more concerned with backup power solutions. Severe weather events like Hurricane Sandy have magnified the need for backup power. The two most common home backup power technologies are generators and batteries. Before we dive into which technology is best for your home, let’s discuss your current energy usage. The average daily electricity consumption of an American household is around 30 kilowatt-hours (kWh), but ranges from about 16 kWh to 40 kWh. Utility rates, temperature, lifestyle, and environmental conscientiousness are some of the key factors that account for the variance in electricity consumption throughout the country.
Additionally, consumption is usually not evenly distributed throughout the day. Home electricity consumption typically peaks in the morning when people wake up, cook breakfast, and run the coffee machine. Electricity consumption peaks again in the evening when Americans get home from work, turn on their lights, cook dinner, and watch TV. It is important to understand when you use electricity so that you can reduce your consumption during a blackout. Why should you reduce consumption during an outage? Both of these technologies by themselves are more expensive than your utility and their use should be limited if possible. Therefore, during a power outage, your backup power system should be able to provide slightly less energy than you use on an average day.
Your Backup Power Options
There are two types of backup power systems most popular with today’s homeowners: batteries and generators. Batteries are usually mounted behind your home’s electrical meter, and they can be charged from any source of electricity. For most homeowners, that means that you charge your batteries with electricity supplied from the grid. However, homeowners with solar panel can also charge their batteries using energy from their solar panels. (These homeowners can also charge their batteries with electricity from the grid.) Generators, on the other hand, are connected to your home’s main gas line (or to a dedicated tank, depending on availability and preference), and burn various types of fuel (usually natural gas) to generate electricity.
Choosing the Right Option
Both have advantages and disadvantages, so choosing between the two is not always an easy task. How do you make the decision? What are the main criteria involved?
Let’s start with the basics: how long do you expect an outage to last?
In most urban and suburban areas, power outages rarely – and only under catastrophic circumstances, such as natural disasters – last for more than a few hours. 7-10 kWh can cover the power requirements of an average home for one evening. If you are conscious of the power outage, you can also reduce consumption as the utility works to get the grid back up. Both generators and batteries can supply the 7-10 kWh needed for a short power outage so the choice boils down to economics and environmental impact. A generator costs between $1,500 and $5,000 depending on brand and quality. You can expect to pay an extra $500 to $1,000 for installation. Batteries that can store 7-10 kWh can cost $3,000 to $5,000, but these systems also require an AC/DC power inverter (typically around $2,000) and professional installation (around $1,000). In total, you can expect to pay more upfront for a battery system, but you won’t have to pay for fuel like you would for a generator. Additionally, there are environmental impacts to consider. Batteries, especially when storing power from solar panels, are more environmentally friendly than fossil fuel generators.
If you want to prepare for longer outages or want to go completely off the grid, there are other factors to consider. For example, over a period of four days US households use about 120 kWh. In order to store that much energy with battery technology, you would have to purchase several batteries, which is likely to be prohibitively expensive. Generators, on the other hand, have the same upfront cost whether you wish to generate power for a few hours or a few weeks. You still have to pay for the cost of fuel, but running a generator for a four day long outage is significantly cheaper than buying batteries that can store enough energy to power your home for that same period of time.
A generator will continue to provide energy as long as it has fuel to run on. However, running a generator for two weeks – while certainly possible – is expensive and polluting. For instance, with a Diesel generator, you can get about 7-10 kWh per gallon of fuel, which means you would need 3.5-4 gallons per day. The cost of fuel is not the only thing you need to consider; if you use a fuel like gasoline, you need to think about storing it safely. You could also run your generator on natural gas and connect to the main gas line. However, in the event of a natural disaster, a gas outage is often just as likely as an electricity outage. In fact, these shortcomings – high fuel cost and potential safety hazards — are what historically causes some homeowners to consider solar power as an alternative source of power when the grid goes down. Paired with the latest battery system, solar panels can provide a reliable source of energy during an outage.
How would a “Solar + Battery” backup power system work? Solar panels would generate power during daylight hours, and batteries would store that solar energy for use at night. Solar + Battery backup power systems can provide energy for extended power outages and can even be used to go completely off the grid. Additionally, you can use the solar panels to generate free power when there isn’t an outage, which can save you thousands of dollars on your electric bill. There are even financing options available for solar with zero upfront costs for those who qualify. (You can check out our free solar calculator to see how much you could save with solar.)
How long you want to have power during an outage is the most important question homeowners have to answer when deciding on backup sources of power. However, there are a lot of other variables to take into account including generator maintenance, safety, fuel storage or gas line connection, environmental impacts, and sun exposure. These factors, as well as those mentioned above, can vary significantly by region. We suggest speaking with a local service provider specializing in home backup power. These professionals can lend expertise and help you make the best decision for your family and your home.