The Sola Basic 4000 VA does three layers of boost, and one of buck. It is about 1/3 the price of the Hughes, but you do have to add an input plug and an output plug. I went a bit farther so that I could monitor the input voltage as well as output.
I use the extra female input outlet to add surge protection to the system (Thanks Mex), as well as monitoring voltages.
first boost is at 110 volts and is 10%
second boost is at 110 volts and is 20%
third boost is at 90 volts and is 30%
Buck is 135 volts and is -10%
Suppose input voltage is 104. Output will rise to about 114. This is a much superior result compared to the PI units that would cut off the power. If we look at the SG at 102 then output is still a healthy 112 volts.
With these OEM settings, boost would occur before the air conditioner had finished 'spinning up'. Later, I added the microair unit and boost no longer happened (shot myself in the foot?).
My boost voltages were 'dead on' from the factory. I've since adjusted them up by 2 or 3 volts. I've not had a chance to try the roof air with these higher set points, but I'm hopeful that I'll be back to boost during A.C. spin up.
I use mine often, even in winter. The boost in winter lets me get the full wattage output from heaters.
There is also something called an 'ecowise' which apparently keeps voltage dead on 120, no matter what the input voltage is. Had I known of that unit, I would have purchased it.
I do get some ems from the Magnum hybrid inverter. When on 30 amp shore power, I use the Magnum to limit input to 24 amps, and on 15, I limit to 12 amps.
I've seen the Sola do a 20% boost--but never the 30%. It does boost right down to 85 volts, according to the skimpy manual, and that would be approximately 110 volts of output, given a 30% boost.
The numbers above are calculations and real life is some what different. I have a real life measurement when input voltage was 97. Output was 107. That is why I tweaked the boost set points up. I won't have a chance to test that for a few months.
Here is the 'path':
shore power-->surge-->Sola Basic-->Magnum-->RV
Regards, Don
My ride is a 28 foot Class C, 256 watts solar, 556 amp-hours of Telcom jars, 3000 watt Magnum hybrid inverter, Sola Basic Autoformer, Microair Easy Start.