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Choosing an inverter for your home can be tricky. In most cases, an installer will handle this for you. Along with selecting a reputable installer, there are a few other things to look for when choosing an inverter.
Picking the right installer
Knowing what kind of solar panels and equipment you want for your home is only one half of the battle. Finding the right solar installer for the job is the other half. Solar is a huge investment, and you want to make sure that your system is installed correctly the first time around.
“I think the biggest decision a homeowner can make is who’s going to install their system. So having certified companies with the right qualifications with a track record in the area, and you know they’re going to install it correctly,” Kristopher Davis, an associate professor of materials science and engineering at the University of Central Florida, told CNET. “And if there is a problem, they’ll be around years from now so they can provide service.”
When searching for a solar installer, look at their track record and how many solar projects they have installed. Try to find an installer that has experience working with the type of roof that you have and the type of install you’re looking for. If you plan to have a solar battery installed, pick an installer that has experience with that as well.
A reputable installer will conduct a roof inspection beforehand and an energy audit to find out what type of solar set up is ideal for your home. Your installer should also walk you through all your options and be able to answer all your questions clearly, no matter how difficult those questions might be.
“I would defer to their track record. When someone’s a brand new installer, that’s when they make more mistakes. And if they’ve been installing a lot of systems for many years, that’s one of the best things about them,” French said.
Certain installers will also offer a performance guarantee to make sure your system was installed correctly and is still operating correctly after a certain amount of time has passed. Davis says you should also see if the installer can help you understand how to monitor your solar panels. If there’s a big drop in energy production, you’ll want to know what the process is like if something goes wrong and who to contact. Davis says if your installer doesn’t have answers for those types of questions, that’s a red flag.
Weigh all your options and get quotes from multiple installers in your area for the best price possible. Getting a mix of quotes from national and local installers will give a decent price variety.
System functionality and compatibility
Your solar inverter needs to be compatible with the rest of your solar panel system. Off-grid or partially off-grid systems are going to require a different type of inverter than one that is for purely on-grid purposes. Most solar inverters will fall into one of these three categories.
Grid-tied inverter: Grid-tied solar inverters are the most common inverter type you’ll come across. As the name suggests, these inverters require a grid connection to operate and are capable of pulling power from the grid as well as feeding power to the grid. However, if the power grid ever goes down, a grid-tied inverter will automatically shut off too, which leaves you prone to power outages even with solar panels. To avoid outages, a solar battery and additional equipment needs to be installed. Grid-tied inverters are normally cheaper than hybrid and off-grid options, too.
Hybrid inverter: A hybrid inverter is a solar inverter and a battery inverter combined into a single unit, designed to offer an on-grid and off-grid power solution. However, you can still install a hybrid solar inverter without a battery. Solar batteries need a battery inverter to be able to power your home. Some solar batteries on the market come with their own built-in (or integrated) battery inverter. But if a solar battery doesn’t come with a built-in battery inverter, you’ll need to install a compatible third-party one. A hybrid inverter could be an option in this situation. Just keep in mind that hybrid inverters are typically pricier than regular grid-tied solar inverters.
Off-grid inverter: An off-grid inverter is designed for off-grid solar panel systems. These draw power from solar batteries to operate and to keep the power on during the day and at night. This type of inverter cannot be connected to the grid and should only be installed if you have plans to live completely disconnected from the power grid. You’ll likely also need multiple batteries to truly live free from the power grid.
Inverter size
When it comes to inverters, size matters. It’s important that your inverter is sized properly with your solar panel system to avoid efficiency and power reduction issues. Your inverter’s maximum AC power output should match your solar array’s maximum energy production (DC power). If your solar panel’s DC energy production is greater than your inverter’s maximum AC power output rating, it can result in solar inverter clipping, limiting how much energy is actually delivered to your home. You’d lose out on chunks of electricity generated by your solar panels.
Your inverter’s wattage should match the wattage of your solar panel system. If you have a 7,000-watt solar panel system, your inverter size should be at least 7,000 watts, too. But when it comes to solar products, you’ll likely see kilowatts (kW) used as a unit of energy measurement more than watts. That’s fine — the same rule still applies with kW. If you have a 7 kW solar panel system, your inverter size should also be at least 7 kW (7,000 watts). Getting a solar inverter with a much larger wattage than your solar array can cause efficiency and performance issues.
An installer will properly size your inverter with your solar panel system based on the size of your solar array and the amount of sunlight your home receives throughout the day.
Warranty
As with any expensive purchase, you’ll want to know your inverter’s warranty, along with the specifics on what costs are covered and what costs you’ll be paying out of pocket. Most solar inverters come with a limited warranty. The limited warranty will typically cover five to 12 years (depending on the manufacturer). Most manufacturers will cover an inverter or part replacement under the limited warranty, butwill not cover the labor cost to install the part or the associated shipping fees. Shipping and labor costs are more likely to be covered under an extended warranty, which comes at an additional cost. These extended warranties can cover anywhere from 15 to 25 years.
Make sure to carefully read through an inverter’s warranty document to see what costs will be covered.
Inverters with multiple components will typically come with separate warranties for each component. DC power optimizers are a component that is frequently purchased with string inverters, but since these are two separate components, the string inverter and DC power optimizers will likely have separate warranties. Roof equipment, like DC power optimizers and microinverters, will normally have longer warranty coverage than wall equipment. Twenty-five years is the industry standard for microinverter and DC power optimizer warranties.
Inverter efficiency
Inverter efficiency is a measure of how efficient your inverter is at converting your solar panels’ DC electricity into AC electricity to power your home. The higher your inverter’s efficiency, the less electricity you lose over time. However, it’s important to note that an inverter’s efficiency will never be 100%. This is because some energy is lost to heat or is used by the inverter during the conversion process. Energy can also be used to power the inverter when it’s on standby.
Experts also say inverter efficiency does matter to a degree. But what matters more is choosing the right type of inverter, like string inverters or microinverters, and solar set up for your home
“With efficiency, I wouldn’t go so far as to say it’s a red herring, but generally pretty much all inverters nowadays are 95-plus percent efficient,” Kurchin said. “So that’s unlikely to be kind of a make or break for any real practical application.”
There are two different inverter efficiency ratings to pay attention to: peak (maximum) efficiency and California Energy Commission (CEC) efficiency, with CEC efficiency being the more helpful of the two ratings.
Peak efficiency: An inverter’s peak efficiency (also known as maximum efficiency) rating indicates how efficient the inverter is at converting the solar input (DC) energy into home electricity output (AC) energy when it’s operating at its optimal (or rated) capacity. In other words, this is a measurement of your inverter’s efficiency when it’s performing at its best.
CEC efficiency: California Energy Commission efficiency is most commonly referred to as CEC efficiency and is a weighted efficiency rating that reflects the inverter’s performance range across various DC input amounts. An inverter isn’t always going to operate in “optimal conditions.” You’re going to have periods of indirect sunlight throughout the course of the day. CEC efficiency is a weighted efficiency rating that takes into account different load factors at different voltages, which gives you a more accurate representation of how efficient your inverter is actually going to be on an average sunny day.
“The actual efficiency of your inverter is going to be some sort of weighted efficiency based on how much power is going into it at different times and at different efficiencies, at those different powers,” Kurchin said. “And so the CEC efficiency rating is trying to get some sort of general estimate for that by making measurements of the inverter at different percentages of its rated power.”
To get its CEC efficiency rating, the inverter is tested by a third-party, California Energy Commission-approved laboratory. Check out the CEC Solar Equipment List Program for a comprehensive list of CEC-tested products.
Europe also has a similar weighted efficiency rating called the “European efficiency rating.” This rating has the same premise as the CEC efficiency rating, but weighs in different assumptions during the calculation.
Apps and user interface
Your inverter is the central hub, or “brain” of your solar panel system. With the correct software in place, your inverter will be able to continuously collect data on your home’s energy consumption and how much electricity your solar panels are producing. Most inverter manufacturers create an app that allows you to monitor this data. More advanced inverter software will usually include features that help users control their power loads, avoid time of use rates and store your energy data to help predict your monthly energy bill and ways you can save. Long story short — the more ways you can control and interact with your solar panel system, the better.
However, these apps are not without their flaws. Some solar monitoring apps can be buggy and might not always update you with your solar system’s data when they’re supposed to. Reading through user reviews on app stores can give you a decent understanding of what you’ll be experiencing when using a specific solar app.
The bottom line
The “best” solar inverter for your home depends less on the inverter manufacturer and more on what your home’s specific energy needs are. Your solar panel system size and the conditions on and around your roof play vital roles in determining what type of inverter setup is best. Experts emphasize picking a solar installer with a good track record of the type of solar install you’re looking for.
If you want something smaller than a whole-home solar system, see our picks for the best portable solar panels and solar generators.
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