Frankman60
Member
During the simulated grid outage test I found that my Panasonic Inverter type microwave oven was running slowly (half speed). Is that because it has an inverter? Our other GE built in microwave oven worked fine.
-
Want to remove ads? Register an account and login to see fewer ads, and become a Supporting Member to remove almost all ads.
My proposed system can't power my AC
- Thread starter hodad66
- Start date
nwdiver
Well-Known Member
Where did you see 66Hz? I'd be surprised if it's that high. Most inverters that use frequency shifting only go up to ~62Hz and that's unlikely to have any noticeable effects. The tolerance for grid-tie inverters is SUPER-tight. 59.3 - 60.5 is the band defined by UL1741. You might have something else going on... voltage?
SSonnentag
埃隆•馬斯克
I got it from here:
And once the battery level in the Powerwalls drops a bit, the frequency returns to normal:
nwdiver
Well-Known Member
That's really odd... did you check against utility frequency to make sure your meter is reading correctly? Since no grid-tie inverter can operate >62Hz I don't understand why it would run at 66Hz...
SSonnentag
埃隆•馬斯克
We have Sunny Boy inverters, but they were manufactured in 2009, so I wouldn't be surprised if their acceptable frequency parameters were a bit different back then.
SSonnentag
埃隆•馬斯克
SSonnentag
埃隆•馬斯克
I checked my old documents from 2010 when we had our PV system installed. The Sunny Boy docs do indeed show an operating frequency range of 59.3 Hz-60.5 Hz. So either those specs are incorrect with what the hardware actually does, or more likely, the Tesla Powerwalls aren't quite as intelligent as they should be and they increase the frequency WAY more than they need to in order to keep the inverters offline.
SSonnentag
埃隆•馬斯克
The info here: Powerwall/Solar Edge behavior in power outage
sounds promising. I'll have to check my frequencies again as I've had an update since the previous pictures were taken.
sounds promising. I'll have to check my frequencies again as I've had an update since the previous pictures were taken.
nwdiver
Well-Known Member
Yeah... 66Hz is a bit much. That's high enough to negatively effect all sorts of stuff. Any motor is going to run ~10% faster and any plug-in clock is going to gain ~6 minutes/hour. Good chance even my mini-splits wouldn't work.... although they're designed for parts of the world where electricity could be generated by a donkey on a treadmill so they do appear somewhat bullet-proof. Can you spot all the split units? Only 'merica uses window units....
Ulmo
Active Member
That is amazing. I want more numbers. My imagination flowers with the following what-if, and I want to know if the numbers make sense:
Well, I can see from the above that in coastal areas of California, the multi-split heat pump units could be sized properly and installed in parallel with existing forced air central gas heating systems in poorly insulated older construction homes (the late 1950s early 1960s housing boom in California), and then the gas systems only used for the purpose of every 5 to 20 years when an extremely cold spell (5ºF - 20ºF) comes to coastal areas (extremely rare), and the rest of the time, the multi-splits can operate down to whatever temperature they could pull up from around the teens or twenties, and sized to be efficient at a higher temp than you would need if they were the only heater. I'm seeing the price for the HVAC equipment coming to around $7,000 plus or minus, so with labor, around $10K or around that. I could see that being afforded by many homes converting over to electricity heating in the coastal areas, and California could even do a government loan program for that sort of thing. Then, in about 10 to 20 years when those loans are paid off, the same homes could, each in their own time, slowly put in rock wool sound and heat insulating wall, ceiling, and floor insulation, slowly encapsulating the homes with more and more insulation, and bringing down the minimum temperature those heat pump systems could originally heat from. In about 20 years, gas heaters would become redundant, and perhaps even some sort of backup heating system could be installed in that timeframe for the extreme five times per century cold spells, and the gas service disconnected and turned off. PG&E could start uninstalling gas service statewide in 20 to 25 years. The financials of it would be about even for customers, and some homeowners would even save money.
This is a reasonable way to cost effectively transition ourselves away from 100% fossil fuel heating our individual homes into electric heating, which is much easier to turn into clean energy heating since electricity can be made many different ways. What do you think? If this makes sense, we could start a new thread.
Ulmo
Active Member
Wow. I count my lucky strikes. During my testing, no electronics failed. I stopped testing, though, for many reasons.
My computer server has been up over nine months, and would have been longer if I had not done software updates or PowerWall system testing. The PowerWalls have been supplying steady power that long.
Last edited:
When I say "fire up" I mean the AC condenser.
At no point in my experiments did the powerwalls stop producing power or shut down.
Without solar, and 100% on battery power the house browns out (even with a properly rated and installed SureStart)
When the house browns out the thermostat (EcoBee) reboots (due to low voltage) and the call for cooling stops so everything returns to normal as soon as the thermostat reboots.
In my testing however, I did notice that if the solar is producing that plus the batteries has enough power to turn over the AC condenser and we're off to the races. Once the AC is started the batteries can run it without issue.
This is a workable solution for me.
During an extended outage if it's hot (there is usually sun) I can turn on the AC during the day when things are producing and just keep it on to pull the house down really cold for the evenings.
Fingers crossed that I won't have to test it
Frankman60
Member
I just tested a simulated grid outage with the following conditions:
- Powerwall charge level 100 percent
- Solar producing 5 kW of energy
Frankman60
Member
You mentioned that solar plus PW energy is enough to start the AC condenser. Do you know how many kWs are needed from the solar for this to happen?
I think I have a similar situation with an AC compressor with a 135 LRA and 2 PWs. Presently I see a “brown out” like you mentioned when trying to start the AC on PW power only. I haven’t tried it when their is significant solar energy being produced (say above 3 kWs). I haven’t decided whether to try the SureStart or move the AC to the non backed up loads panel yet.
I think I have a similar situation with an AC compressor with a 135 LRA and 2 PWs. Presently I see a “brown out” like you mentioned when trying to start the AC on PW power only. I haven’t tried it when their is significant solar energy being produced (say above 3 kWs). I haven’t decided whether to try the SureStart or move the AC to the non backed up loads panel yet.
When I say "fire up" I mean the AC condenser.
At no point in my experiments did the powerwalls stop producing power or shut down.
Without solar, and 100% on battery power the house browns out (even with a properly rated and installed SureStart)
When the house browns out the thermostat (EcoBee) reboots (due to low voltage) and the call for cooling stops so everything returns to normal as soon as the thermostat reboots.
In my testing however, I did notice that if the solar is producing that plus the batteries has enough power to turn over the AC condenser and we're off to the races. Once the AC is started the batteries can run it without issue.
This is a workable solution for me.
During an extended outage if it's hot (there is usually sun) I can turn on the AC during the day when things are producing and just keep it on to pull the house down really cold for the evenings.
Fingers crossed that I won't have to test it
When I ran my test I didn't check how much solar I was producing unfortunately.
I'd have to do more testing around that.
As completely fabulous as the PW2s are when they work properly, the "66 Hz problem" is real, serious, intermittent, and persistent. I discovered it when doing a week long off-grid test of my grid-tied system in March of 2019 (www.SomiSolar.com). When the PW2's state of charge (SOC) reaches the threshold, the PW2 gradually ramps up the line frequency until the solar inverters experience a grid fault and shut off. That's "normally". At random times, however, off-grid PWs respond to reaching the SOC threshold by snapping the line frequency to 66 Hz, then refusing to come back down until the SOC is depleted a few percent. When the line frequency is at 66 Hz, the central A/C's controller cannot function, every UPS in the house beeps, and the microwave oven is disabled. Turning the PW2s off and back on does not resolve the problem, but running the clothes dryer to deplete the charge a few percent works every time. Today the PW2s locked up and stayed that way until my wife ran the clothes dryer. After that, the PW2s cycled off the inverters correctly 5 times in a row. The intermittency of the malfunction has distinct implications that I won't get into here.
It's true that some inverters have a high cut-off frequency (e.g., some, but not all, of the SunnyBoy models). I reprogrammed the high cut-off frequency on one SunnyBoy inverter but the problem persisted. I've also seen the same problem with Enphase microinverters, a SolarEdge inverter, and a SunnyBoy model that had a low cut-off frequency. Our grid-tied inverters are not the problem.
I've been working back and forth with technicians at Tesla Energy for months to get the issue resolved. Tesla's technicians can see the problem and they have promised to fix it. They sent technicians to my house and they monitored the problem remotely. They have tweaked the PW2 parameters, and pushed firmware upgrades to the units. Unfortunately, every one of their varied hypotheses for what's causing the malfunctions have fallen by the wayside. The most recent hypothesis was that my two PW2s were out of balance with each other and were disagreeing about whether to turn off the solar inverter. Nope. While the two PW2s may have drifted out of balance after 5 days off the grid, battery imbalance was not causing the "66 Hz problem". The problem appeared today when both PW2s had the same SOC.
Bottom line is that running off-grid during an outage has proven to be a hit-or-miss proposition: one needs to stay close to the house to operate the clothes dryer and fix the intermittent malfunctions that happen mid-day. Maybe Tesla can design a robot that turns on the electric clothes dryer for 20 minutes when the line frequency locks up, or maybe I have to do it myself (move over Rube Goldberg). I look forward to posting a happier ending to this frustrating story.
It's true that some inverters have a high cut-off frequency (e.g., some, but not all, of the SunnyBoy models). I reprogrammed the high cut-off frequency on one SunnyBoy inverter but the problem persisted. I've also seen the same problem with Enphase microinverters, a SolarEdge inverter, and a SunnyBoy model that had a low cut-off frequency. Our grid-tied inverters are not the problem.
I've been working back and forth with technicians at Tesla Energy for months to get the issue resolved. Tesla's technicians can see the problem and they have promised to fix it. They sent technicians to my house and they monitored the problem remotely. They have tweaked the PW2 parameters, and pushed firmware upgrades to the units. Unfortunately, every one of their varied hypotheses for what's causing the malfunctions have fallen by the wayside. The most recent hypothesis was that my two PW2s were out of balance with each other and were disagreeing about whether to turn off the solar inverter. Nope. While the two PW2s may have drifted out of balance after 5 days off the grid, battery imbalance was not causing the "66 Hz problem". The problem appeared today when both PW2s had the same SOC.
Bottom line is that running off-grid during an outage has proven to be a hit-or-miss proposition: one needs to stay close to the house to operate the clothes dryer and fix the intermittent malfunctions that happen mid-day. Maybe Tesla can design a robot that turns on the electric clothes dryer for 20 minutes when the line frequency locks up, or maybe I have to do it myself (move over Rube Goldberg). I look forward to posting a happier ending to this frustrating story.
Today I got an email from the local Tesla install planner making sure that
I knew that the AC would not be included in my backup. I called my AC
contractor to make sure that my compressor was a scroll type. The dude
(Tesla) from Orlando then found two differing documents saying that the
compressor was first reciprocating but then confirming that all Trane units
in this group are scroll compressors!!
Sure hope that this works out. I don't know if I could run AC all the time after
a hurricane for days but I sure would like to ignore a 2 or 3 hour outage as
if it never happened!!! Fingers crossed......
I knew that the AC would not be included in my backup. I called my AC
contractor to make sure that my compressor was a scroll type. The dude
(Tesla) from Orlando then found two differing documents saying that the
compressor was first reciprocating but then confirming that all Trane units
in this group are scroll compressors!!
Sure hope that this works out. I don't know if I could run AC all the time after
a hurricane for days but I sure would like to ignore a 2 or 3 hour outage as
if it never happened!!! Fingers crossed......
It should work. I have two Powerwall2 unis from which I run my 3 ton Lennox A/C (with a soft-start) (2.7 kW) and charge my car with a level 2 charger (6.6 kW) and run a 30 amp inline water heater. No problem. Twice I've run the house off-grid for a week -- just finished a 6-day rainy season off-grid test run yesterday. I've never had the Powerwalls shut down from too much current draw. A friend of mine with a similar system had to turn down the temperature on his mongo inline water heater, but then everything ran fine. If you want to see screenshots of everything working off-grid, you can look at my blog posts on www.SomiSolar.com.
@Phil Stoddard have you had a moment to see my post re: frequency issues? My grid outage frequency issue is resolved!
Your setup is a bit different than mine (different inverters, 2x powerwalls) but have hope that with the new firmware and some more pestering Tesla can update your configuration to more reasonable frequency settings (62.5hz vs 66hz).
Your setup is a bit different than mine (different inverters, 2x powerwalls) but have hope that with the new firmware and some more pestering Tesla can update your configuration to more reasonable frequency settings (62.5hz vs 66hz).
