If you connect your panels to the grid, you won't be responsible for producing all your own energy. That's not the case if you go off the grid.
Going solar doesn't mean going off the grid -- unless you choose to.
Grid-tied systems have a give-and-take relationship with the wider electrical system, drawing from it when needed and sending excess energy back. Off-grid systems place you on your own solar island, which means you'll be responsible for producing all of your own energy. Whether you want your solar panels to operate in tandem with the grid or not is something to consider when shopping for solar panels.
The US electric grid, a network of power plants, transmission lines and distribution centers, provides power to more than 150 million customers nationwide. Understanding how solar panels and the grid work together can help you decide if you want to be energy self-sufficient or grid-dependent. Programs like net metering, in which your utility pays you for excess power you send to the grid, and the use of batteries allow utility companies to work in tandem with solar panel owners -- a move that experts said is mutually beneficial.
Grid-tied solar systems tend to be cheaper and allow for greater flexibility, according to Sam Evans-Brown, executive director of the advocacy group Clean Energy New Hampshire. "The vast majority of electric consumers are not going to want to go off the grid," Evans-Brown said in a phone call.
However, you can choose to go off the grid completely. Depending on your reasons for going solar and your proximity to the grid itself, off-grid solar may be the best fit for you.
If you are in the market for solar panels and are contemplating whether or not to connect to the grid, here's what you need to know to help you decide.
The relationship between your solar system and the electricity grid determines whether you're a self-sustaining energy producer or you rely, at least partially, on public energy. Most solar panels are integrated with the grid, according to a 2015 study from the MIT Energy Initiative. Read on to learn about their differences.
As the name implies, grid-tied systems are connected to the electrical grid via net metering, which allows for two-way movement between your solar array and the grid, or another method. This allows you to draw electricity from your utility company as needed. Since solar panels rely on sunlight to generate power, this is particularly important if you live in an area that frequently experiences overcast or rainy days.
Grid-tied solar systems tend to be the cheapest and most flexible option. Because you won't rely entirely on your panels for all your energy needs, there are typically fewer upfront costs in the form of energy storage systems. However, your utility may charge you connection fees.
Many solar panel owners prefer to stay connected to the grid so they can take advantage of net metering, which offers credits in return for the energy you sell back to the utility company. You can find a list of incentives in your state on the Database of State Incentives for Renewables and Efficiency.
So long as you're connected to your local utility grid, you won't need to worry about producing all of your own energy. When your panels aren't producing enough electricity, you'll draw from your utility company and be billed for what you consume. It's possible the credits you receive for contributing surplus energy from your panels to the grid will substantially, if not entirely, offset those costs.
"That extra electricity has to go somewhere and the grid has to do something with it, but they are willing to pay us for it, which is nice," Kim Quirk said in a phone call. Quirk is a branch manager at ReVision Energy, a New Hampshire-based solar provider.
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People who live in remote locations or who want to use 100% clean energy may lean toward off-grid systems.
With an off-grid solar system, you will have no physical power lines or wires leading to your home (except from your own solar panels), nor will you receive any bills from a utility company or retail electric provider. An off-grid solar system runs independently by generating electricity and storing that power in batteries. When your panels are less productive, you'll draw from those stores as you would the grid through net metering.
If you opt for an off-grid solar system, you will be responsible for meeting your own energy needs. An off-grid solar array requires an extensive energy storage system to ensure you don't experience power failure during periods of low sun exposure. Depending on the size of your home and your energy needs, you may need more than one battery. Some homeowners also choose to install back-up generators.
|Grid-connected solar system||Off-grid solar system|
|Connected through power lines and net metering||No physical power lines or net metering|
|Do not have to produce all of your own energy||Produce all of your own energy|
|Solar energy storage system is optional||Solar energy storage system is necessary|
|Potential utility connection fee||No utility connection fee|
Grid-tied solar systems impact how utilities generate and distribute their power -- particularly during peak energy use hours.
Solar panels help the grid by smoothing out the supply curve, which represents the cost of an energy resource and the amount of energy available at that cost, according to a 2018 report from the National Renewable Energy Laboratory.
Electricity produced through grid-tied systems and stored through batteries can offset or reduce demand, alleviating stress to the grid. Utility companies have to match consumer demand and electrical generation in real time in order to maintain grid stability. That causes prices and system stress to vary considerably throughout the day. The spikes in demand for electricity -- typically during the morning and early evening -- are often when prices are the highest because of the strain on the grid.
That's where net metering comes into play. When the sun is shining and solar panels produce more energy than a home can use at one time, that excess energy flows back into the market. By adding to the utility's power supply during peak demand, solar panels help to smooth out that spike.
In the same way solar panels can smooth out peaks in the grid's supply curve, they can also stress it. When solar panels aren't able to produce enough energy, homeowners have to draw from the grid -- adding to the strain on the grid's system. Particularly during the shorter days of winter when solar power generation becomes less effective, people rely more on the grid during peak hours, steepening what's known as the duck curve.
The duck curve is a measure of solar power generation and energy demand. Plotted on a graph, it looks like a duck. Solar panels operate best in direct sunlight, typically in the middle of the day -- which is also when demand for electricity is lowest. The duck curve deepens as more solar panels overgenerate during off-hours but taper off as the sun goes down and demand for electricity spikes.
"We have to understand the grid's perspective," Quirk said. "If everyone goes solar, then the grid has too much electricity in the summer and not enough in the winter."
In addition, while excess energy from solar panels can benefit the grid during peak hours, there is potential for over-generation -- particularly in states with high solar-adoption, like California. When too much energy is fed into the grid, the frequency surpasses its typical equilibrium. Such changes in frequency, either faster or slower, can cause damage to the wider energy infrastructure.
Energy storage will make it easier for you to rely on solar energy even when the sun isn't shining. While solar batteries are a must for an off-grid solar system, they provide benefits to any solar system.
"If people have solar as well as a battery, they can use the solar in the day to feed their houses and charge their batteries. And at night, the batteries will serve their houses instead of the grid," Quirk said. "It makes people a bit more independent from the grid when we tend to see big spikes."
Grid-tied systems are dependent on utilities. When there is a blackout or grid failure, solar panels without batteries become useless. With a solar battery system, though, you can safely power your house during an outage.
Solar batteries can be a costly investment, ranging from $12,000 to $22,000 depending on the exact size and type. To reduce upfront costs, you can apply the 30% federal solar tax credit toward solar batteries. Some states, like California and Maryland, have financial incentives, in the form of tax credits and rebates, to help people access energy storage.
It's important to work with a reputable solar installer to help you select a battery that fits your needs -- whether you want to go off the grid entirely, have a backup power source in case of outages or reduce your electric bill during peak hours.
While requirements may vary from provider to provider, connecting your solar array to the grid is fairly straightforward.
The average cost of a home-size solar battery ranges from $12,000 to $22,000.
Going off the grid has the potential to save you money if you live in a remote area where power lines don't reach. The cost of extending a power line to your home can range from $15,000 to $50,000 per mile. The farther you are from the grid, the more expensive it will be to connect to it. Not only will your solar panels provide reliable electricity in rural areas, but you won't have to pay for a utility connection.
While less common, going off the grid is still a viable option. It mainly depends on your reasons for going solar and your geographic location.
100% clean energy: With an off-grid solar system, you generate and use 100% clean energy, unlike with grid-tied solar systems, which rely partially on nongreen sources.
Rural areas: Off-grid solar panels can provide reliable electricity in areas where the grid doesn't reach -- and you won't have to pay to extend your utility connection.