If you’re building any sort of solar system, the quality and size of your power inverter is critical in order to effectively convert the DC power your harnessing into useable AC power. Generally speaking power output is the most important factor to consider when choosing an inverter, but we’ll cover more on that later. This page will outline some of the other important factors to consider when buying a power inverter as well as the different types and uses. We’ll also outline some of the most popular brands.
You’ll notice when shopping for an inverter that there seems to be a fair amount of technical jargon that may be slightly confusing at first. That being said, let’s quickly cover some of the basic technical terms we'll want to understand.
Amps: the flow rate of "electrical current" that is available. Mathematically, Amps = Watts / Volts
Amp Hours: a unit of electric charge, having dimensions of electric current multiplied by time, equal to the charge transferred by a steady current of one amp flowing for one hour.
Continuous Watts: Watts is a measure of the amount of electricity being used - a rate of electrical power consumption. Watts = Volts x Amps
Watt Hours: Watt-hours measure amounts of energy for a specific period of time, and watts measure rates of power at a moment in time.
Volts: the potential difference across a conductor when a current of one amp dissipates one watt of power. Mathematically Volts = Watts / Amps
Peak/Surge Power: This is the most power the inverter can supply at any one time usually for up to a few seconds to a maximum of 10-15 minutes. Think for example when a sump pump kicks on, this will be the peak surge.
Typical/Usual Power: This is the amount of the power the inverter will supply on a continuous rating and will usually be quite a bit lower than the surge.
Types of Inverters:
Pure Sine Wave: These types of inverters are by far the most popular type (although they are usually more expensive) because they provide cleaner more high quality energy (similar to grid tie quality) which means you shouldn’t have any issues when it comes to actually using the power you’re converting.
Modified Sine Wave: Modified inverters are generally cheaper because they provide a lower quality energy which can sometimes cause issues with the appliances, and things you’re actually trying to power. Although they work great for smaller, off grid applications, they tend to be a little noisier and rougher which leads to being less efficient overall that a pure sine wave.
Off Grid vs. Grid Tied Power Inverters:
The difference between an off grid and grid tie inverter is the fact that grid tied inverters can feed power directly into the grid whereas off grid inverters will require a battery bank to run off of, as this is where the inverter will draw the power that it will then convert for you to use.
We’ve outlined some buying tips to keep in mind when shopping for your power inverter - First, when deciding on what voltage you need, your solar panels, power inverter and battery bank all need to use the same voltage. When it comes to the watts rating, you’ll want to get an inverter that is almost equal or slightly more than your system’s watts rating so if you have a 3000-watt system, you’ll want a 3000-watt inverter.
If you’re looking to run multiple appliances off of your inverter, the easiest way to calculate whether the inverter will be able to handle it, is to add up all the continuous watt ratings of each appliance that will be running at the same time. Again, the same principal applies for surge watts, you’ll want to add up the potential largest surge watts from your appliances and ensure the inverter is that many watts or slightly more. Most appliances will list their surge directly on them and from there you’ll want to assume that the surge is generally 1.5 to 2 times as much as the continuous watts. So if the highest surge watt rating on one of your appliances is 2000, you’ll need a power inverter with a little more than 2000 surge watts.
Most Popular Off Grid Inverters:
Schneider: More than a solar inverter manufacturer, the solar business of Schneider Electric provides the complete solution for the solar power conversion chain.
Outback: OutBack Power inverter/chargers have a reputation of delivering superior product performance for remote off-grid power systems. With the recent introduction of the Radian Series Inverter/Charger, OutBack now offers an ideal solution for advanced Grid/Hybrid applications and full flexibility for grid-interactive and off-grid installations.
Magnum Energy: Manufactures exceptional inverters, inverter/chargers, and accessories catering to mobile applications including utilities, corporate fleets, RV, marine, trucks and renewable energy applications. Manufactured in Everett, Washington, and St. Paul, Minnesota and shipped worldwide.
Most Popular Grid Tie Inverters:
Enphase: Is on a mission to bring solar energy to the next level, one where it’s ready to meet the energy demands of an entire globe. As Enphase works towards their vision for a solar-powered planet, they are committed to three core principles: innovation, quality, and responsibility.
SMA: SMA is setting the standards today for the decentralized and renewable energy supply of tomorrow. More than 3,000 SMA employees in 20 countries have devoted themselves to this task. Their innovative solutions for all photovoltaic applications and our unsurpassed service offer our customers worldwide greater independence in meeting their energy needs.
SolarEdge: SolarEdge is a global leader in smart energy technology. By leveraging world-class engineering capabilities and with a relentless focus on innovation, SolarEdge creates smart energy solutions that power our lives and drive future progress.