Sometimes we let fear stop us from moving forward. Here’s a good show stopper kind of question; “what if my new <insert appliance here> doesn’t work on my genverter?” It may not be the end of the world, and often we can adapt our behavior to make it work. Remember our motto, “Adapt, Improvise, and Overcome!!“
Before we work on the answer here, I’d like to mention that a power budget for your system might prevent this kind of situation. If you have your genverter system all put together and find that some appliance does not operate, there are several things to check. What is the appliance surge power? Look through the available documentation. Next, what is the surge rating for your inverter?
The kinds of appliances that will tax any system are large electric motors used in deep wells or used for compressors in air conditioning or refrigerators. The start-up surge can be 3 or more times the power for normal operation. This large demand generally only lasts a couple seconds, but if power is not available for this it will not start!
Most well known quality inverters like Xantrex, will provide 2 or 3 times their rated power for a few seconds to overcome the surge requirements of these motors. If you have a electric motor based load that will not start on inverter power, there are a few things to check.
First, make sure the device is operating correctly on grid power. Sounds strange, but it is possible and does happen, its broken somehow and you’re busy working on the wrong problem.
Second, make sure all options are off on the appliance to insure it takes the minimum power on start-up. This will minimize the initial power surge, that may be just enough to get you over the start up hump!
Third, see if the device will run on your generator source alone. Make sure the generator is rated for the maximum running power of your device. Generators by their rotating mechanical nature will do well for surges in starting up electric motors.
If your device or appliance works on the generator and not the inverter then consider the possibility of making it generator time only use. If this is practical in your situation, its using “free” power in the sense that you’ve already paid for it, but it would not be normally used. See: Free power time! In our home several items fit this category; the dishwasher, Jackie’s electric iron, and under normal circumstances, the deep well pump to fill the water cistern.
If nothing above works, then consider getting temporary access to a larger generator and testing with it. Unfortunately, if that works it is probably your best solution. If you must have this appliance or device, then start shopping for a good deal on a larger generator and or inverter. This kind of situation is rarely happens when you start your off grid power system design with a detailed power budget.
What are the large loads or appliances you operate, or want to operate on a genverter? Tell us about it below in the comments!
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Some appliances have more than one motor; or several solenoid valves plus a motor pump that all start simultaneously. See if you can sequence these to start one after other to minimize the surge and spread out the total load over a longer time period. Wood burning boilers for hydronic heat are popular for off grid applications but they use both a circulation pump and a forced draft blower. By inhibiting the circulation pump while the forced draft blower starts up will reduce the starting surge. The rating plate for any motor usually gives running amps and locked rotor amps. The surge will be 3X the running amps but less than the locked rotor amps. Motors fitted with capacitors also draw less to start than motors without starting caps.
Yes, motors with starting caps, or “soft start” are our friends. I remember struggling with my well and an undersized generator years ago. It wasn’t pretty, no motor, no well, no water. We had to cut short our visit!