Hwy89Hwy89 wrote:Nope it won't work without a live grid connection. Get a non grid tie type it will likely cost less.
I have doubts about your plan. I think you will need a battery bank to provide the amps when the compressor starts. Low voltage and insufficient power on motor start is a sure way to release the magic smoke.
.Alan B wrote:Elaborating a bit on what Hwy89 cal workers trying to work on the grid when it is intentionally powered off. >>>> matt responds: i expect in the future, it will break the tie when the grid goes dark. and keep the house on solar power! why it doesn't do this now is beyond me.
Solar panels are very unstable power sources, and standard inverters need a more stable source, such as batteries, to work from. They will error out on panels alone.
Perhaps you could use a very small battery bank, and rely on the inverter shutdown when the batteries deplete. When the panels are again providing power (and the batteries have charged somewhat) you could restart the inverter.
I wouldn't believe that until I had seen it, using a scope and a current probe.Matt Gruber wrote:That was exactly my plan, until i saw a small $99 freezer at home depot. they claim it needs 65-90 watts, and only 1.2 amps on start.
I think that's a mod-sine; again, check with a scope.so if true it could start on 200w panels in bright sun. [/quorw]
As others have mentioned that won't work with a standard grid tie inverter. Might work with a large solar array and an SMA inverter; they have a "secure power" option that can be used without grid present. But if that fridge needs 1kW to start for even a single cycle then your array has to be >1kW - and it won't start unless you are in full sun.i thought i may need a sine wave inverter, not sure what is in my UPS APC NS 1250, probably high quality since they guarantee it wont damage your equipment. Just kicking around ideas. thanks!
.Alan B wrote:That is not a sine wave. That is called a "modified sine wave", but it is really a stepped square wave with 3 values - 0, +peak and -peak. By timing it they generate something that has less distortion than a pure square wave, but it is still fairly poor compared to pure sine wave. Some loads will fail with a modified sine wave, others run ok or make some extra noise.
Your PWM solar regulator should be set for the SLA voltages, so it will not let the raw panel voltages get through. The SLAs will provide some "inertia" and the voltage should ramp up slowly, but be stopped by the charge controller before it gets too high as the batteries charge.
I wouldn't believe that until I had seen it, using a scope and a current probe. (billvon wrote).billvon wrote:Matt Gruber wrote:That was exactly my plan, until i saw a small $99 freezer at home depot. they claim it needs 65-90 watts, and only 1.2 amps on start.
It's going to be hard for a non-technical person to tell just by looking. Easiest way is with a scope; look at the output and see if it's a sine wave or not. A less reliable way is to use a cheap (non-RMS) digital multimeter and see if the voltage it senses is way out of whack with what the voltage rating of the inverter is.Matt Gruber wrote:So how do they make a sine wave? Can't i just open up an inverter and look for what?
With that context it sounds like a pretty good plan actually, just in general I would caution people against them. cheersMatt Gruber wrote:Knee
i got a free freezer and a free UPS. if either burn up after the next hurricane, i'll take your advice. i plan a test every 6 months, will run the freezer for 1/2 to 1 hour, mainly a battery test, but also a test of your theory. there are numerous utube videos of freezers running on any inverter. none burned up, a few would not start.
my tv , LED's, radio, ebike, scooter, hotplate, and fan, ALL run off DC, so no problem there. all these will work without an inverter! These are why 2 solar panels are a great idea.
i plan to run the freezer 2-3 days before a hurricane, on grid ac, to make 50-100lbs of ice before the power fails, so, i'll be set for 2+ days with ice.