How you plan to use your pure sine wave inverter is one of the most important considerations in deciding what inverter to buy. First, does the inverter need to be portable – for example, for use on an RV or boat – or does it need to be hassle-free because it will be installed in a difficult to reach area as part of an off-grid home? Or if you are using your inverter in conjunction with a solar array, finding inverters that are capable of combining solar with grid power can be a huge energy and time saver. In addition, considering what and how many appliances and devices you plan to power off an inverter will play a large role in determining the wattage and surge power capabilities that you need.
The wattage available from your power inverter is one of its most important specifications, since this number determines what you can power and how many devices you can power at a single time.
Before choosing an inverter, take a look at the wattage requirements of the devices you plan to use most often with the inverter – your inverter will need to output at least the wattage required by each device, and at least the sum of the wattage required by devices you plan to power simultaneously.
In addition, motor-driven devices often have higher wattage requirements to get them started, and your inverter needs to deliver enough power to meet that requirement. When in doubt, springing for an inverter with a higher wattage will cost more money, but also leave you more powering options later.
Continuous power and surge power
Inverters are typically rated in watts for both the amount of power they can continuously put out over periods of minutes to hours – known as continuous power – and the amount of extra power they can put out for a few seconds – known as surge power.
Continuous power dictates which and how many devices you can power simultaneously. Surge power is extremely important to consider if you have motor-driven devices, which often require more power to start up than to run once they have started.
For example, a chainsaw that requires 1000 watts to run may require 2000 watts to start – and if your inverter cannot supply 2000 watts or more of surge power, the chainsaw will not start.
Typically, sine wave inverters are designed to output the same voltage as standard electrical outlets in the country for which the inverter is marketed. That means in the US, sine wave inverters are designed to output 120 volts. The voltage, current, and wattage outputs of an inverter are related, such that for a fixed voltage a higher wattage will require a higher current.
Buying a power inverter that has built-in overload protection is a good idea to protect both your inverter and the battery and devices you have plugged into it. Overload protection forces the inverter to automatically stop pulling power from the battery when the amount of current running through the inverter is greater than what the inverter is rated for, which can happen when powering multiple devices at once.
If you’re planning to use solar panels to recharge your battery, you need to think ahead when buying an inverter. Most inverters cannot feed power directly from solar panels to the battery without a battery bank to store and convert the power coming from the solar panels. However, using a battery here is rather pro than con, since solar panels are passive generators of electricity. They don’t store energy and are highly dependent on sun and weather, so you’ll need a battery to store the energy such panel produced anyway.
Many modern pure sine wave inverters come with one or more USB ports, which can be extremely handy additions since so many small electronic devices can be charged by USB. The only caution to using the USB ports for charging is to remember that they do draw from the same output wattage that is being delivered to other appliances plugged in to your inverter, so keep an eye on the total number of watts you are asking your inverter to deliver versus how many it is rated for.
Although LCD displays may seem like a luxury on a power inverter, they can make a huge difference in troubleshooting if you have issues with your inverter, since the screen provides error codes that are easily looked up in the manual. If you are purchasing your first power inverter, or have a particularly complicated setup, it may be worth purchasing an inverter that has a built-in LCD screen.