What is the Difference Between a Grid-Tied Solar System and an Off-Grid Solar System?
When you decide to power your home with solar energy, you have the option to choose between an off-grid solar system and a grid-tied solar system. Let’s break down the differences between each of these types of systems.
- A grid-tied solar system is the most common type of solar system. A grid-tied solar system is connected to the city’s utility grid. When your home uses more power than your solar system can supply, the electrical grid supplements your solar energy. Conversely, when your solar system produces more than your home consumes, excess energy is returned to the power grid. If the electrical grid goes down (i.e., if the power goes out), you are affected by the outage. Even though you’re producing your own energy through your solar system, being connected to the grid means your energy can be turned on and off by the utility company.
- Note: In most states, including Oregon and Washington, solar owners receive credits for the excess energy that their grid-tied systems produce. This is called Net Energy Metering, and it reduces the monthly cost of your energy bills even further.
- An off-grid solar system is far less common. Off-grid solar systems are not connected to a utility grid. Instead, excess energy is stored in a battery connected to the homeowner’s solar system. When you use power at night, when your solar panels are producing very little energy, power is drawn from the battery’s stored energy.
- Note: Even if you live in a rural area, you do not have to go off-grid with your solar system. The vast majority of homeowners – including those in Eastern Washington, Eastern Oregon, and rural parts of Idaho – have the option of connecting their solar system to the power grid.
- A grid-tied solar system with a battery, or a hybrid system, offers the best of both worlds. This type of solar system allows homeowners to take advantage of the net energy metering incentive, while also remaining self-sufficient if the power grid goes down. If the grid loses power, your solar system will draw power from your battery and you will not lose power.
Components of an Off-Grid Solar System
Off-grid solar systems are more complex than grid-tied solar systems. There are several elements that make up the basics of an off-grid system:
- Solar Panels: Solar panels are the foundation of every solar system. The size and quantity of solar panels will depend on several factors, including roof size, orientation, and the amount of shade and sunlight the roof receives. This will then determine the production power of your solar system. For many homes, especially in the Pacific Northwest, the production power of your solar panels isn’t enough to fully power an off-grid system. Read a more detailed explanation of this in the “Disadvantages” section below.
- Solar Batteries: Often the most expensive component of the setup, a solar battery is essential to an off-grid system. The battery stores excess energy produced by your solar panels, which your system then draws from to allow you to keep the electricity running at night and in the winter when production is low. Oftentimes, off-grid systems require multiple solar batteries in order to harness all of the excess energy produced by the solar panels.
- Solar Charge Converter: The charge converter is essential to regulating the solar battery (or batteries) in an off-grid system to ensure energy is being used efficiently. The charge converter controls the current and voltage the battery receives, preventing any damage and eliminating the risk of overcharging the battery.
- Solar Inverters: The energy created by solar panels is direct current (DC) energy, which is not usable until it is converted into alternating current (AC) energy. The solar inverter converts the AC energy into DC energy. These are also sometimes called PV inverters or solar converters. Every home powered by solar requires a solar inverter, but off-grid solar systems use standalone solar inverters.
- Backup Energy Source: An additional source of energy is not required for an off-grid system, but many homeowners with off-grid systems opt for backup generators for security. A backup source of energy ensures you won’t lose power on the darkest of winter days.
To find out your home’s storage capabilities and to get a full cost breakdown of your potential solar system, get one of our free solar audits.
Benefits of Off-Grid Solar
For some homeowners, going completely off-grid makes sense. Here are some reasons why a homeowner would choose an off-grid solar system instead of a grid-tied one:
Benefit of Off-Grid: You’re Not Tied to the Power Grid
- The most practical advantage of off-grid solar systems is that the grid’s power outages do not affect you. If the power grid goes down, an off-grid system isn’t affected, because it’s not tied to the electrical grid. Grid-tied solar systems are connected to the power grid, which means that homeowners with grid-tied systems experience power outages when the grid experiences outages, unless they have installed a battery backup.
- This is often particularly appealing for homeowners who live in areas that experience frequent power outages due to weather, such as the Oregon coast, or rural areas, where a downed power line takes longer to get serviced, causing long outages.
Benefit of Off-Grid: You’re Not Paying the Utility Company
- Going off-grid allows you to become completely independent of the utility company. Essentially, you cease doing business with them. This means that you’ll never receive a power bill again, and you’re not subject to any of the utility company’s policies or rules.
- With an off-grid solar system, not only do you cease purchasing power from the utility company, but you will also no longer pay any of the utility company’s service fees or demand charges (these are fees that are often charged to customers for using electricity during the times of day when it is in highest demand). With a grid-tied system, you may still incur these fees, depending on your utility company.
- With an off-grid system, you’re completely insured from increases in the utility company’s fees. Utilities tend to increase at about twice the rate of inflation annually. The independence of an off-grid system means you’ll never be affected by these increases.
- Note: Despite these advantages, going off-grid is still more expensive than a grid-tied system, due to the cost of batteries and installation of an off-grid solar system. See the breakdown below in the “Disadvantages” section for a more detailed explanation of this.
Benefit of Off-Grid: Allows Remote Homeowners to Go Solar
- In some (increasingly rare) cases, such as new construction in a highly remote locale, or underdeveloped communities, your site may not be connected to the power grid. In these instances, it may make more financial sense to go off-grid than to build a grid-tied system. If the site is more than .25 miles from an existing power line, it will likely be more cost-effective to go off-grid than to extend the power line in order to create a grid-tied system.
Disadvantages of Off-Grid Solar
At Smart Solar, we almost always recommend that our PNW customers opt for a grid-tied solar system, rather than an off-grid solar system. There are a few reasons for this:
Disadvantage of Off-Grid: Solar System Sizes in the PNW Make it Difficult
- In Oregon and Washington, it is difficult to build a big enough solar system to go completely off-grid. The size of your solar system depends on the orientation of your roof and the amount of sun and shade you receive. It’s rare for a home in the Pacific Northwest to have enough roof space and sunlight for a solar system large enough to power an entire home. As an example, if your roof can accommodate a solar system that produces 7 kWh, but you requires 10 kWh to fully power your home, you won’t be able to go off-grid.
- Note: This isn’t a bad thing! The majority of people can’t offset their entire power bill with solar. However, going solar still makes you more self-sufficient and sustainable. Imagine if you had a well on your property with the best water on Earth, but it could only provide 70% of the water you needed, and you had to buy the other 30% of your water from the utility company. Would the well still be worth it? Absolutely! You’d still have the best water in the world the majority of the time. That’s what going solar in the Pacific Northwest is like.
- To find out if you can go off-grid, you’ll need to do some calculations. You will need to determine:
- Your current energy usage
- The storage capabilities of your roof
- The production capacity of the panels that your roof can accommodate
To find out your home’s storage capabilities and production power of the panels you can install, get one of our free solar audits.
Disadvantage of Off-Grid: It Costs More
- Off-grid solar systems are inevitably more expensive than grid-tied solar systems. Creating a large, off-grid solar system is a complex construction project. Oftentimes, in order to create a sufficient supply of power, homeowners who go off-grid have to install additional panels outside the roof. These are called ground mounters, and they typically make sense only for large properties with ample space to install additional panels. Ground mounters can be connected to the main system by building trenches and pipes to the energy meter.
- Additionally, the battery (or multiple batteries) must be installed and connected to the entire system. Batteries are expensive and each of these elements add complexity, which increases your total cost.
- Homeowners who choose to go off-grid lose out on the net energy metering incentive offered by most states. Net energy metering compensates solar-powered homeowners for the extra power they supply to the grid by providing rolling energy credits toward your power costs when your solar system is producing less energy than your home consumes.
Disadvantage of Off-Grid: It Requires Maintenance
- In order to keep an off-grid system running effectively, the batteries have to be maintained by the owner. This requires a basic understanding of electrochemistry (or a willingness to learn) that may be overwhelming or too time-consuming for those who aren’t determined to be 100% self-sufficient.
- Valve regulated and gel batteries do not require as much care or maintenance as flooded batteries, especially if you have a charge controller. Flooded batteries can be susceptible to sulfation—a process of crystallization that disrupts the chemical reactions your battery should experience. This is caused when the battery has a low charge or electricity level. If sulfation happens, your battery may be damaged and become less efficient over time.
Disadvantage of Off-Grid: Lifestyle Change
- You may have to adjust your lifestyle to using less electricity in order to ensure your energy use doesn’t exceed the production power of your off-grid system. This could mean sacrificing some modern conveniences, and instead using candles at night instead of the lights, or only charging your devices when you need them.
Where is Solar is Headed? Grid-Tied, Off-Grid, or Hybrid Systems?
Solar technology is at its prime, and the current incentives for going solar are unbeatable. At Smart Solar Energy Co., we encourage all of our homeowners to switch to solar now, before the incentives change. The current federal tax rebate on solar systems is a 26% dollar-for-dollar match, but in 2021, it will be reduced to 22%. This incentive will continue to decrease year after year.
Similarly, net energy metering is an incentive that is changing. Right now, most net energy metering practices are set up to give homeowners equal energy credits in exchange for the solar energy they produce. However, some utility companies are beginning to give solar owners lesser credits in exchange for the energy their homes send to the grid. We predict that this trend will be adopted by more utility companies over time.
The good news is that homeowners who go solar now will be grandfathered in to the net energy metering ratio that the utility company has in place at the time of their switch – meaning, if your utility company offers equal credits for solar production at the time you go solar, and switches to 50% credits a year later, you’ll still experience the equal credit value that was in place when you switched.
For homeowners with utility companies that aren’t offering equal credits for net energy metering, we recommend opting for a hybrid grid-tied solar system that produces less energy than the home requires overall, and installing a battery to store any additional energy that is produced on sunny days. With this type of small, hybrid system, you’re still saving on your utility bill by switching to solar, and you’re not giving any power to the utility company. Instead, the excess energy produced by your system is stored onsite in your battery.
As more utility companies reduce the value of net energy metering, more homeowners will opt for hybrid solar systems that store excess energy in a battery, rather than giving it back to the power grid. With the current net energy metering and federal incentives in place, there has never been a better time to go solar. Incentives are only going to be reduced as time goes on.
To lock in the current incentive rates and determine the best type of solar system for your home, get a free solar audit today.