I'm not an EE, but I am at least familiar with power factor. Normally I wouldn't concern myself with it unless I was looking at big three phase motors, i wouldn't have thought about things like my Dishwasher or Dryer. I was aware the startup amps on a compressor are high, but honestly I was going to worry about that later. Seems like something a capacitor kit for your outside unit can solve.ripple4 wrote: ↑Wed Mar 31, 2021 8:49 amIn the planning phase it might helpful to not look at the real power, which is the nameplate values on motors etc, but instead the apparent power of your appliances. as you may know, apparent power is 'real' power plus 'reactive' power, or real power divided by the power factor. with grid-tie you may have been living in a real power dreamland, where motors start easily without dimming the lights, and all motors are created equal perhaps (PSC, ECM, induction) etc. also those large condenser units you are looking at with PSC motors will have a starting current that is going to be impossible to meet with an inverter. my 3-ton condenser unit compressor has an LRA of 155amps, you'll need an ECM (inverter drive) compressor for off grid. In an off-grid situation the inverters supplies apparent power, so when summing all your loads you need to divide the nameplate value by the power factor, or better yet measure it with an amp clamp meter. Recently, I just power factor corrected some of my often used appliances so that my inverter had to work less hard, my gas dryer motor had a power factor of .45, so it was drawing '670va' of current while doing 300w of work. with a 75uf run capacitor I got it to .90PF which dropped the AC current draw by 3 amps. here is the website i use to calculate what capacitor to use. https://www.rapidtables.com/calc/electr ... lator.htmldanrjones wrote: ↑Wed Mar 31, 2021 7:13 am
Right now my heating is being done by an old NG furnace. It is going to need to be replaced soon, but I haven't quite made up my mind on whether I do a newer more efficient furnace or a go ahead and get a Heat pump. Right now all my AC is done by a evaporative cooler. My evap cooler has a low and high setting, and on high its pulls 1 HP plus a water pump, so ~ 750 watts plus the pump, lets say 50 watts. So 800 watts. From June through end of Aug that mostly runs on high non stop, so about 19.2 kWh per day. Obviously if I got a heat pump I could also run that as an AC, and my wife would love that, and turn off the swampy. I would need a 5 ton unit for Heat pump/AC. I tried to do some estimating before I put in my solar so that I could cover that if needed. I believe a 5 ton AC uses about 6 to 6.5 kW sustained, but obviously it wouldn't run the entire day like my swamp cooler.
One item i'm keeping my eye on is this product. if it works out like they advertise it will be a big deal, since it will create reactive power and make everything better. https://www.maxoutrenewables.com/evergrid
I would imagine, though could be totally wrong, that my 1 HP Swampy motor is the biggest sinner at the moment. Its 240v but single phase.
Still have no idea what direction I will go anyway. I really don't want a heat 15 kW heat strip. A new furnace with a heat pump could work but it adds cost for a furnace I might never use, given today's efficient heat pumps. The heating issue (replacing the old furnace) is really my driving factor, as my swamp cooler itself works just fine, other than increasing water prices and comfort issues.