New Lux Power LXP-LB-US 12k / GSL-H-12KLV-US with 200A AC Passthrough Current (US Market)
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Brucey
Solar Wizard
Should one take edge effects into account when sizing number and config of panels into an MPPT, in addition to perhaps 15% safety margin for low temps?
Hedges
I See Electromagnetic Fields!
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I don't think cloud edge effects do much to Voc.
Temperature is important. I might use 16% (-15 degrees C, -0.4% per degree C deviation from +25C) for very conservative without any more math, but temperature coefficient from PV panel data sheet and record cold temperature for your location lets you safely cut it closer. Many good panels don't have as large a coefficient.
I'm not so worried about Isc or Imp limits, assuming quality MPPT SCC, so just use PV label figures and don't consider cloud edge. SCC can protect itself (unless you leave connected backwards for a long time.) Wires and breakers/fuses are taken care of with the 1.56 multiple.
Temperature is important. I might use 16% (-15 degrees C, -0.4% per degree C deviation from +25C) for very conservative without any more math, but temperature coefficient from PV panel data sheet and record cold temperature for your location lets you safely cut it closer. Many good panels don't have as large a coefficient.
I'm not so worried about Isc or Imp limits, assuming quality MPPT SCC, so just use PV label figures and don't consider cloud edge. SCC can protect itself (unless you leave connected backwards for a long time.) Wires and breakers/fuses are taken care of with the 1.56 multiple.
llaforest
New Member
Hello, I just got my new LuxPower 12K gen3 inverter with 20kW GSL batteries. In order to get 4000$ in subventions here in Quebec, I need 4000W of solar to go with it. I have heard that a weakness of the LuxPower compared to the SolArk is its efficiency with large bi-facial panels. In my case, I will be installing the panel on a sloped metal roof so bi-facial is not needed but does anyone here know what panels would be best to maximize efficiency of my inverter?
Quattrohead
Solar Wizard
I have no idea where you heard that from, it will use the power it can get from the panels.
Respect the voltage and current limits and it will work perfectly fine with regular or bifacial panels, it does not know the difference and it does not matter.
Respect the voltage and current limits and it will work perfectly fine with regular or bifacial panels, it does not know the difference and it does not matter.
Luxpower_Gilbert
Luxpert @Luxpower USA Team
You can over panel the inverter, just don’t over-voltage.
edgecrusher
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@elusivesd : Can you share the custom code for emulating the SDM630? Really keen on making something like this work! Even just a github link would be awesome!
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llaforest
New Member
Yeah I'm not sure where that came from so this is why I wanted to ask in here... Anyway I was told for my metal roof to go with Hi-MO LR5-72HPH. I would need minimum 8 panels to get max subsidies from govt... In that case they would all be in series I assume.
Quattrohead
Solar Wizard
Very rough calculations say you can have upto 12 panels in series that will give you around 6kw per string.
PV1 can take 2 strings and PV2 & 3 can do 1 string each. All will be over paneled a bit but within reason.
But you must read the manual and make your own decision about how many panels you want to add per string and how they will be configured.
PV1 can take 2 strings and PV2 & 3 can do 1 string each. All will be over paneled a bit but within reason.
But you must read the manual and make your own decision about how many panels you want to add per string and how they will be configured.
I'll see if I can write up something this weekend, the code is still sitting on my old laptop (and is embarrassingly bad!)
Background: Originally needed a solution to control backfeed on a GTIL2 inverter without the use of the original CT clamps. If unfamiliar, the GTIL2 functions in a closed loop - will "ramp up" power output when input is pulled low, and "ramp down" power output when pulled high (from memory, don't shoot me if reversed). Steady power output effectively looks like a 50% PWM duty cycle.
Hardware: CircuitSetup single/split phase energy meter => ESP32 (Arduino sketch) => GPIO pulsing pseudo-pwm to GTIL2 inverter input
GTIL2 software logic:
Loop:
- Read power from ADC
- If value > threshold (~100W), set GPIO output pin to RAMP_UP
- if value < threshold, set GPIO output pin to RAMP_DOWN (excess backfeed, reduce power)
Eventually, I outgrew this setup and moved on to the LXP inverter. Of course, metering options are different - either by using CT clamps, or Eastron SDM meter over RS485.
Hardware modified: CircuitSetup => ESP32 => RS485 => LXP
LXP software logic:
Loop:
- Read power from ADC
- Set global vars (Total Watts, Volts A, Amps A, Volts B, Amps B, etc..)
- Convert values to register compatible format, set registers (emulating Eastron SDM)
- If/when LXP requests register data for information, latest info will be retrieved
Each loop will complete within about 15ms (~1 AC cycle), limited by the ADC and LXP polling rate. The data itself is near real-time.
There's more to it, but this is a high level overview of functionality. Let me know if you have any questions!
edgecrusher
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Awesome! If you can share portions of the ESP32 code, I'm going to do something very similiar. Only potential hiccup/modification is that I might try to go: CircuitSetup ==> ESP32 (at Mains), parallel post to emoncms/HA ==> MQTT ==> ESP32 (in powershed) ==> LXP
If the MQTT +Wifi isn't fast enough (even if I offset 500W or something so that I don't ever backfeed), I might do a longer RS485 network (wired).
I think I found the right register mapping for SDM, but would appreciate knowing what the minimum required registers are, and that I'm populating the right ones. I haven't ordered my LUX yet, so bench testing/planning are in order.
Thank you!
Hedges
I See Electromagnetic Fields!
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As in one ground network for PV array, one ground network for everything else?
You can, and may be required, to have a ground rod for the array.
You need to have a wire bonding frames of PV array to frames of electrical equipment in the house, where frame ground bonds to AC neutral and goes to a ground rod.
There may be some problems the extra ground rod can cause, such as a nearby lightning strike creating a large voltage difference across the earth and current flowing through the ground wire back to house. Hopefully a very unlikely event.
If PV frames do not have ground wire bonding them back to everything else, that often is found to carry 60VAC at low current, making it a shock hazard. This varies by inverter, but many people here have reported it. Also, a fault in the array could make the frames a high voltage DC hazard.
You can, and may be required, to have a ground rod for the array.
You need to have a wire bonding frames of PV array to frames of electrical equipment in the house, where frame ground bonds to AC neutral and goes to a ground rod.
There may be some problems the extra ground rod can cause, such as a nearby lightning strike creating a large voltage difference across the earth and current flowing through the ground wire back to house. Hopefully a very unlikely event.
If PV frames do not have ground wire bonding them back to everything else, that often is found to carry 60VAC at low current, making it a shock hazard. This varies by inverter, but many people here have reported it. Also, a fault in the array could make the frames a high voltage DC hazard.
Two separate grounds are not recommended or required. No matter what you will need to run an grounding conductor, bonding the panels and mounts, with your pv wires, and connect to the ground bar at the inverter.
I would recommend only using listed disconnects, breakers, surge protectors, and enclosures for your PV circuits. IMO, and midnite solar, have listed products. For a single string no over current protection, or disconnect are required at the panels or on the roof. Many inverters have a built in PV DC disconnect, and a separate disconnect at the inverter would not be required.
Grid input disconnect doesn't need to be fused and class t fuses aren't required if you want to use them, Grid input disconnect will not provide rapid shutdown on a battery inverter. Automatic transfer switch should be listed. If generator has built in breaker fuses not required in disconnect, class t not required if used.
RSD switch must be connected to tigo CCA for shutdown of roof mounted panels.
Hedges
I See Electromagnetic Fields!
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What does Tigo CCA have to do with rapid shutdown?
Tigo Cloud Connect Advanced (CCA)
One of the smallest solar data loggers on the planet, Tigo's Cloud Connect Advanced (CCA) enables valuable insight into module level performance data. It is the hub for data from Tigo's O, S and M products and customers can also connect their inverters, batteries, building meters, and more...
www.tigoenergy.com
Does Luxpower inverter provide keep-alive for Tigo RSD? I think it is done that way with SolArk. [Edit, I think 12V out to external keep-alive]
How about discharge of input capacitors? Turning off Tigo RSD boxes stops supply of voltage, but capacitor bank might remain higher voltage than allowed for some minutes. I may have to address this if I move panels to roof for some older grid-tie inverters - I'll use separate Tigo keep-alive transmitter.
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The Tigo optimizes, and other modules that are used with the CCA, do not use the powerline keep alive signal for rapid shutdown, they only communicate wirelessly, and they receive the keep alive signal from the CCA, via TAP over RF. So when using tigo optimizers and the CCA, power must be removed from the CCA to initiate rapid shutdown.What does Tigo CCA have to do with rapid shutdown?
Tigo Cloud Connect Advanced (CCA)
One of the smallest solar data loggers on the planet, Tigo's Cloud Connect Advanced (CCA) enables valuable insight into module level performance data. It is the hub for data from Tigo's O, S and M products and customers can also connect their inverters, batteries, building meters, and more...
Does Luxpower inverter provide keep-alive for Tigo RSD? I think it is done that way with SolArk.
How about discharge of input capacitors? Turning off Tigo RSD boxes stops supply of voltage, but capacitor bank might remain higher voltage than allowed for some minutes. I may have to address this if I move panels to roof for some older grid-tie inverters - I'll use separate Tigo keep-alive transmitter.
Quattrohead
Solar Wizard
Page 56-58 of the manual -
In case of emergency, press the rapid shutdown
button to cut off the RSD power supply, in turn
cutting the inverter’s AC Output along with
dropping the PV Conductors voltage to <30V in 30 seconds.
The inverter has it's own RSD button and you can connect an external one too.
Also the PowerPro batteries have a connection to add an RSD button and the inverter/batteries communicate this information and will trip each other off when signaled to do so.
Yes rapid shutdown should go to the LuxPower as well, this can be a separate contact on the shutdown switch, although documentation on this seems very limited for this inverter, and may vary by variant. If the CCA is powered by the inverter output shutting down the inverter via RSD should shut power output off and when the CCA loses power the modules on the panels will go into rapid shutdown as well. Some documentation cliams the aux contact on the CCA can also be used to initiate RSD on the panels, this can be used if the CCA is powered from battery, or other sources.
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