Solar Inverters

Most homes are wired for AC electricity, but most solar panels and small wind turbines produce DC electricity. Solar inverters convert direct current (DC) electricity into alternating current (AC) electricity. Because of this, unless your solar system runs DC only, an inverter is usually a central component in both off-grid and grid-tie solar systems. Each type of system requires a different type of inverter:

The three types of solar inverters:

  • Off-grid inverters where a charge controller sends DC power to a battery bank, then an inverter converts the DC to AC for the home.
  • Grid-tie inverters with no battery bank, DC power goes straight to the inverter, and then to the home as AC. Excess AC power is sent "backwards" through a special two-way net meter, and out to the power grid for others to use. Your meter runs forward or backwards depending on if you are buying or selling power at the time.
  • Hybrid inverters connects to both a battery bank and the utility grid, letting you draw or send power from both.

Which solar inverter system is best for home use?

  • Battery based inverters are best for small projects or when the grid is not available at your location.
  • Grid tie string inverters are best when you don't have a lot of shading.
  • Micro inverters are best when you have shade on some of the roof or multiple roof orientations.
  • Hybrid inverters are best you want solar and batteries and be connected to the grid.
  • Mobile inverters are best when you're on the go, in the RV or on the boat.
Solar Inverters

More Info on Solar Inverters

Sizing an Off-Grid Solar Inverter

Choosing the right off grid inverter for your off-grid solar system depends on accurately calculating your electrical loads and usage patterns. The size of the inverter you need is based on your 'peak load' requirements - all the AC loads that could be turned on simultaneously.

For example, if you will be using the 1500 watt microwave, while also running 100 watts of lighting and running a refrigerator that will draw 500 watts of power, you will need an inverter that can handle at least 2100 watts (1500 + 100 + 500). Once you have identified a minimum wattage, you will select a style that has the same nominal voltage as your battery bank (12, 24, or 48 VDC).

Sizing a Grid-Tie Solar Inverter

Grid-tie inverters connect directly to the utility grid and do not require batteries. A battery-less system is much less complex (and less costly) than a system with batteries. The main drawback is that a grid-tie solar system without batteries cannot supply power to the home in the event of a power outage. For the safety of the people working on the utility lines, grid-tie inverters will shut down until power has been restored. If frequent power outages are not an issue, then a utility grid-tie system can be an excellent, cost effective option.

To qualify for most state rebate programs, you must be connected to the utility grid. We recommend you visit dsireusa.org/ for the most up to date list of solar and renewable energy incentives in your local area.

Sizing a grid-tie inverter can be a bit more complex than sizing one intended to be used with batteries. Each inverter manufacturer offers a string sizing tool that will display the acceptable configurations for your PV array, based on the quantity and wattage of your solar panels. These string sizing tools also account for variations due to high and low temperature extremes.

String Inverters, DC Optimizers & Micro Inverters


A quick comparison and overview of three types of grid tie inverters: a String Inverter by Fronius, a String Inverters with DC Optimizers by SolarEdge and a Micro Inverter by Enphase.

Grid-Tie Solar Inverters with Battery Backup

Hybrid inverters are designed to hook directly to the utility grid AND allow a battery bank to provide backup power in case of a power outage. These are typically at least 2500 watts and can operate with 24 or 48 volt DC battery banks. Some inverters are now being made to work with Tesla's Powerwall battery.

Inverters for Every Application

Browse our wide selection of off-grid and grid-tie solar inverters. We also offer marine/mobile, micro, and hybrid versions, capable of working in both off-grid and grid-tie applications. Questions about these, or perhaps string sizing for inverters? Call an altE solar system expert today at 877-878-4060!