Or at the very least I'm reducing power consumption while atempting to inch my way off grid. My first small step towards off grid was power factor correcting my air compressors and welding machines. Originally I did this to allow then to work better on long extension cords, be more efficient and make then draw less amps. Next step, will be to greatly reduce starting inrush current on air comoressors. To do this I am going to try the simplest solution first. And that is a using a closed circuit soft starter made for single phase capacitor start motors. But I have a feeling this may only be marginally effective. The soft starter I found is made by hyper engineering and claims to reduce inrush by at least 60%. I have a feeling if I really want to do away with inrush its going to involve a 3 phase variable frequency drive. Pretty much exactly like what inverter heat pumps and inverter refrigerators use. A single phase soft start for capacitor start motors is fairly simple. It just reduces voltage to the motor while it starts. But there are a few concerns. Single phase capacitor start capacitor run motors use a centrifugal switch to control the start windings. If the voltage is too low or the starting load too heavy and the motor doesn't build up to speed fast enough to disengage the start circuit with in a few seconds it will smoke the start circuit. Also the armatures of induction motors are not designed to work in excess of 6Hz, so the more time spent below about 3,300rpms will build extra heat in the rotor. This soft starter appears have terminals for the start circuit so I'm guessing it may be on a timer to prevent burning out the start cap. I am going to test each compressor on my 5kw, 0 to 300v varrac. Simple test, connect the air compressor to the varrac turn it on and quickly ramp up the power from 0 to 240v within 2 or 3 seconds. Just to figure out which one would works best with automatic reduced voltage starting. I built all my 240v air compressors out of junk I had laying around, or crap I bought from the scrap yard the only thing I really had to buy new for all of them was pulleys and the shut off pressure switch. The main problem with them is the single phase capacitor start, capacitor run motors have really bad inrush current. It also just so happens all my compressors are in the size range for the most common VFD. I have found that 240v single phase input, 3 phase 240v out put variable frequency drives have been getting a lot cheaper. Dont worry about getting 3 phase motors. Small single digit horsepower, delta wound, 3 phase motors that can be wired for 240 or 480v are everywhere because most average consumers cant use them and they are super common in industrial environments. I would prefer a 4 wire wye motor but I don't think its going to happen unless I want to cough up a lot of $. Reason why is I would like to take steps to move off grid, connecting big power hungry air compressors to an expensive split phase power inverter, just seems like its not a good idea. Right now the only way I have to eliminate compressor inrush current is use my 5hp gasoline powered air compressor which can more than match the output of any one of my 240v powered air compressors, but makes a lot of noise and uses some gas. Or use a 12v compressors my Gast air compressor uses a ton of amps and doesn't produce a lot of air and my ARB compressor is just tiny. Other way to protect an expensive inverter from compressor inrush is I could connect the air compressor to a huge generator like my 17.5kw generac or my 7kw troybuilt those do not care too much about high inrush across the line starting but those suck down a lot of gas and make a lot of noise and don't want to run them unless I really need a lot of air. I would like to at some point greatly reduce the inrush current on one of my compressors with a VFD. I figure I can have the motor kick on at 1 or 2Hz ramp up to the desired speed, throttle down to 20Hz then use the pressure switch to release pressure in the line and hopefully signal a turn off signal to power down second or 2 later. Depending on the features and inputs I may be able to have it run at 70Hz part of the time when its building up from 0 to 70psi, 60hz from say 70 to 90psi then 50hz tapering down to 20Hz from 90psi to shutoff pressure. Or something like that. I would need at least a 3 or 4hp, 4 pole motor that could be wired for 240. These are real common. Perfectly good 7.5hp motors are some times scraped where I work because they hire idiots who can't seem to comprehend how trouble shoot motors. One of these TC213 frame motors would work. I think at some point I will get a 3 phase motor and VFD to play with. It's only a matter of time. Another option may be just to get a 24 or 48 volt motor to use with a compressor and just run it straight off the batteries. But I have not made it that far yet.