daklein
New Member
- Joined
- May 8, 2020
- Messages
- 190
I have a system mostly as shown in the attached diagram. Recently have added a separate ~13kwh 14s lithium battery bank which the Midnite CC charges, and 10 microinverters enabled by a relay board discharge the lithium battery mostly at night, or any time there are more loads like the AC load. For a year & half, I've been using 4 microinverters to discharge a ~9kwh 36v lithium battery bank, just at night, the same idea, to avoid as much cycling of the FLA battery. It generally works great although there's always something to adjust in the RPi that controls it all; the FLA battery generally stays full floating, except when larger loads turn on, until the right number of microinverters are turned on to match it.
The conventional old air conditioner is located right outside the basement panel, and the basement to the garage inverters run is maybe 60 feet of #6 copper. The A/C seems to take 4-5kw. I tried increasing the nominal AC voltage of the SIs to 122 from 120, and maybe
The enphase inverters have been set up with different off-grid profiles, one set with a little wider frequency tolerance, so not all of them drop out at once when the SIs ramp up Hz to manage the FLA near full.
When I run the air conditioner, sometimes, the microinverters will not always stay producing. Last summer I did notice a sort of light, variable growling or rumbling noise from the SIs when the AC was on, but everything still seemed to work well. At that point, the 9x305w panels were DC coupled to the FLA as shown in the diagram. I'm wondering if that helped somehow, providing extra DC power to the SMAs, at least in the day. Now I am seeing sometimes that the microinverters are not producing, both day (plenty of AC coupled solar available), and night (a bunch of microinverters discharging from lithium batteries). The nominal reported Hz and voltage are fine, but the data plots are pretty slow rate data every few seconds at the most, so the plot data may be somewhat random-looking aliasing of whatever faster behavior is happening.
In the plotted data from the evening, there are several periods of the A/C running: 20:20 - 20:35, 20:50-21:00, 21:35-21:40, and 22:20-22:25 which I'll call periods 1,2,3,4.
The first period, 20:20-20:35, and 4th period 22:20-22:25 seem to not have the microinverters operating very well. The reported freq is 60hz, +- .05 (green line 4th plot down), and the micros should all stay on until 60.5 by default or 61.3 that I have some set to. Actually, now I see that the 'min' & 'max' values are a bit wider. These are from pretty fast about 10Hz I think CAN data and keeping the min & max over last 75 values. The lithium battery voltage that the micros are taking from (blue line top plot) is noisy and not so much decreased from it's value a minute before when the micros were all off.
Maybe I should be checking the A/C compressor start & run capacitors? I'm not sure why it's intermittent.
I'm wondering about adding a 1kVA 240:32v transformer, it weighs 15-20 pounds, to help smooth the voltage at the basement breaker panel, or maybe that should be close to the microinverters? Can I add some sort of filter to help the micros see a cleaner waveform? Should it be located at the A/C compressor, or should it be located nearest to the microinverters?
One day we'll get rid of the old PSC compressor motor A/C and get a nice variable speed inverter driven geo or airsource heatpump, that'll be easier to run cleanly. Any other lower cost ideas or suggestions please? Thanks!
The conventional old air conditioner is located right outside the basement panel, and the basement to the garage inverters run is maybe 60 feet of #6 copper. The A/C seems to take 4-5kw. I tried increasing the nominal AC voltage of the SIs to 122 from 120, and maybe
The enphase inverters have been set up with different off-grid profiles, one set with a little wider frequency tolerance, so not all of them drop out at once when the SIs ramp up Hz to manage the FLA near full.
When I run the air conditioner, sometimes, the microinverters will not always stay producing. Last summer I did notice a sort of light, variable growling or rumbling noise from the SIs when the AC was on, but everything still seemed to work well. At that point, the 9x305w panels were DC coupled to the FLA as shown in the diagram. I'm wondering if that helped somehow, providing extra DC power to the SMAs, at least in the day. Now I am seeing sometimes that the microinverters are not producing, both day (plenty of AC coupled solar available), and night (a bunch of microinverters discharging from lithium batteries). The nominal reported Hz and voltage are fine, but the data plots are pretty slow rate data every few seconds at the most, so the plot data may be somewhat random-looking aliasing of whatever faster behavior is happening.
In the plotted data from the evening, there are several periods of the A/C running: 20:20 - 20:35, 20:50-21:00, 21:35-21:40, and 22:20-22:25 which I'll call periods 1,2,3,4.
The first period, 20:20-20:35, and 4th period 22:20-22:25 seem to not have the microinverters operating very well. The reported freq is 60hz, +- .05 (green line 4th plot down), and the micros should all stay on until 60.5 by default or 61.3 that I have some set to. Actually, now I see that the 'min' & 'max' values are a bit wider. These are from pretty fast about 10Hz I think CAN data and keeping the min & max over last 75 values. The lithium battery voltage that the micros are taking from (blue line top plot) is noisy and not so much decreased from it's value a minute before when the micros were all off.
Maybe I should be checking the A/C compressor start & run capacitors? I'm not sure why it's intermittent.
I'm wondering about adding a 1kVA 240:32v transformer, it weighs 15-20 pounds, to help smooth the voltage at the basement breaker panel, or maybe that should be close to the microinverters? Can I add some sort of filter to help the micros see a cleaner waveform? Should it be located at the A/C compressor, or should it be located nearest to the microinverters?
One day we'll get rid of the old PSC compressor motor A/C and get a nice variable speed inverter driven geo or airsource heatpump, that'll be easier to run cleanly. Any other lower cost ideas or suggestions please? Thanks!