Using DC Solar Trailer as Rooftop Battery Backup

abilityonline

New Member
Joined
Feb 8, 2022
Messages
31
I purchased a DC solar trailer I'm sure some of you are aware of as many have been purchased. Before using the trailer, I boiled and balanced the 48V led acid forklift battery bank and the batteries are as good as new. I've seen many demonstrate how the 10 235 watt solar panels, are underpowering the battery bank. It comes with (2) SMA Sunny Island model 6048-US-10 single phase battery inverters and MidNite Solar Classic 250 charge controller. (It also has a great 11kw diesel generator backup).

My house has a 13.92 kWp (44 panel) install with two SolarEdge SE7600 inverters that currently backfeed the grid and have no battery backup. My understanding is these SolarEdge inverters should work with AC coupling battery backup. Has anyone used a setup like this for a battery backup? Is it possible to take the power being generated by the trailer and add it to my current rooftop solar? Lastly could I combine the inverter power from the two SolarEdge SE7600 inverters along with the two SMA 6048 inverters to backfeed my house in the event of a grid outage? Thank you in advance for anyone willing to take the time to offer of your expertise.
 

Hedges

I See Electromagnetic Fields!
Joined
Mar 28, 2020
Messages
11,005
A few people here have the DC solar trailers, and some added (or are in the process of adding) AC coupled GT PV.
I have Sunny Boys and Sunny Islands, not from a trailer.

If your SolarEdge do UL-1741-SA frequency-watts, they should work (when that mode is enabled.) Without that, they would cycle on and off every 5 minutes.

You can backfeed the house; I do that with interlocked generator breaker.
If you stick with generator not grid input, pair of Sunny Island should work with up to 24 kW of GT PV.

If you were to feed grid into Sunny Island, using it as a UPS, and put GT PV on the output, limit is 6.7 kW of PV per Sunny Island, so 13.4 kW for two. This is due to 56A limit on bypass relay.
 

abilityonline

New Member
Joined
Feb 8, 2022
Messages
31
A few people here have the DC solar trailers, and some added (or are in the process of adding) AC coupled GT PV.
I have Sunny Boys and Sunny Islands, not from a trailer.

If your SolarEdge do UL-1741-SA frequency-watts, they should work (when that mode is enabled.) Without that, they would cycle on and off every 5 minutes.

You can backfeed the house; I do that with interlocked generator breaker.
If you stick with generator not grid input, pair of Sunny Island should work with up to 24 kW of GT PV.

If you were to feed grid into Sunny Island, using it as a UPS, and put GT PV on the output, limit is 6.7 kW of PV per Sunny Island, so 13.4 kW for two. This is due to 56A limit on bypass relay.
Hedges: Thank you. I see you having replied to many posts. I really do appreciate your expertise. My SolarEdge inverters are UL-1741-SA authorized so that will work well. I have a 400 AMP main electrical panel on my house, It wasn't much more expensive than a traditional 200 AMP box. However one downside is I can't for the life of me find an interlock kit for my panel. I suppose I might have to bite the bullet and get an automatic transfer switch. My trailer is setup with a master and slave sma 6048 for 240volts. One question, my slave has been giving me temp sensors errors, I worked with SMA and they gave up rather quickly (we installed a new batt temp sensor but it didn't solve the error) so they sent me an entire new unit. I was amazed at both how well they honored the warranty and how little they tried to fix my current unit. So if I can somehow fix my batt temp error on my current slave, I would have a master and two slaves. I understand that would increase my output by 6.7kw. Would there be any downside to switching from a Split-Phase System, 240 Vac, up to 12 kW to a Master and two slave combo (Three-Phase System, 120/208 Vac, up to 18 kW)? Or at that point would it make sense to go the extra mile to be able to configure a paired setup with a Double Split-Phase System, 240 Vac, up to 24 kW. Correct me if I'm mistaken but if I want 240 Volts (Which I do) I need to keep the inverters paired. Again Thank you for your time. I appreciate it.
 

Hedges

I See Electromagnetic Fields!
Joined
Mar 28, 2020
Messages
11,005
I think minimum requirement of UL-1741-SA is to ride through for 299 seconds at full power if voltage or frequency makes a small excursion. What I've seen in some documents (not the official ones) that frequency-watts and volts-watts are optional implementations, and only if utility allows.
You'll have to see how yours perform, using a meter to watch frequency. There may be an optional setting you'll want. For SMA, had to request installer privileges when this is done later than initial commissioning.

I had bought Sunny Boy 10000TL-US-12 because listed as compatible. With grid-backup setting, they tolerate wider frequency range but didn't ramp down power output, so frequency ran up to 64.5 Hz, knocked the offline, and cycled back down. SMA support suggested the work-around of setting the to off-grid (was an old model, not current product.) Yours would do similar but around 61 Hz if they don't do frequency-watts.

I didn't think slave would care about battery temp sensor. Only Master's is used. I've thought of installing at least one extra, so if one of my 2s2p setup fails I can reconfigure by flipping breakers and booting another as master, no rewiring needed. Sure that wasn't some internal sensor, not battery related? Did SMA have you send them data from SD card?

Configurations include 2phase2 and 2phase4, haven't checked whether it will run with one of four not responding to roll call.
With 3, can do 3 in parallel (120V only) or 3-phase. 3-phase is attractive, but if your utility service is split phase not 3-phase, you can only connect one 120V phase, so 120V at 56A is all the Sunny Islands can get from grid (or from your generator). They can make the two other phases.

If you can get it working, consider buying at least one more if you want the extra power. But two could be enough. 11.5 kW continuous output at 25 degrees C, 22kW surge for 3 seconds, supports up to 24 kW of GT PV (only if off-grid, not backfeeding through relays.)

For 240V you do want them stacked 2s, or 2s2p. When inverters are in parallel, current through bypass relays is balanced only by resistance. I had 60' of 6 awg, but saw 3:1 current imbalance. That was due to Square-D QO270 breakers, different type (not in those panels) fixed it.

Your two SolarEdge may slightly exceed the 56A AC current which can feed through two Sunny Island. One would be fine. The second one could be put on an interlocked breaker to switch from grid to output of Sunny Islands during an extended outage. Manually allow 5 seconds "off" time after disconnecting one AC source from GT PV inverter before connecting another. (And switch off grid input to the Sunny Islands when you do that, so they don't reconnect when grid comes back.)

Your 400A panel is good for non-interlocked UL-1741 backfeeding by Sunny Island and GT PV. Just leave non-backed-up loads on that panel. Install something like a Square-D 225A panel downstream for manual interlock "generator input" feed from output of Sunny Island, and another panel downstream of the little 100A panel on the trailer for backed up loads.

You should have a "load shed" relay between 100A panel on trailer (maybe upgrade that) and downstream panel. GT PV should land on the trailer's breaker panel (or another you locate on building). The trailer's panel always have AC on, fed by Sunny Island. When the sun comes up, Sunny Boy (or SolarEdge in your case) wakes up to charge batteries. Load Shed relay disconnects downstream panel and loads in the event battery reaches 70% DoD, but panel on trailer remains powered down to 80% DoD (RTFM and you'll see this detailed.)

Another load shed relay can go to the manually backfed 225A panel, which has lower priority loads. Disconnect it as something like 20% or 30% DoD. My plan is to shed things like A/C, water heater, dryer at relatively high SoC, keep computers and refrigerators on until lower SoC. Would also like to turn refrigeration off at night when using battery (my battery is quite small.)
 

abilityonline

New Member
Joined
Feb 8, 2022
Messages
31
I didn't think slave would care about battery temp sensor. Only Master's is used. I've thought of installing at least one extra, so if one of my 2s2p setup fails I can reconfigure by flipping breakers and booting another as master, no rewiring needed. Sure that wasn't some internal sensor, not battery related? Did SMA have you send them data from SD card?
@Hedges, I had the same question for the SMA support staff. Why would a slave error out on a temp sensor that is connected to the master? They said they were connected and if it was faulty it could trip the slave, but I really don't know. I suspect the unit is totally fine. I sent them the downloaded sd card and they just sent me an entire replacement on a pallet to my house. On that note, I'm assuming that I can't swap SD cards on the new unit but need to go through the setup process, but I wanted to see if you knew the answer to that.
Configurations include 2phase2 and 2phase4, haven't checked whether it will run with one of four not responding to roll call.
With 3, can do 3 in parallel (120V only) or 3-phase. 3-phase is attractive, but if your utility service is split phase not 3-phase, you can only connect one 120V phase, so 120V at 56A is all the Sunny Islands can get from grid (or from your generator). They can make the two other phases.
My local power supplier is single phase for residential which is unfortunate because 3phase with three inverters would be a no brainer. If I can get the one inverter to work, I will likely add another inverter to make a 2phase4 setup.
Your two SolarEdge may slightly exceed the 56A AC current which can feed through two Sunny Island. One would be fine. The second one could be put on an interlocked breaker to switch from grid to output of Sunny Islands during an extended outage. Manually allow 5 seconds "off" time after disconnecting one AC source from GT PV inverter before connecting another. (And switch off grid input to the Sunny Islands when you do that, so they don't reconnect when grid comes back.)

If I had 4 SMA 6048 inverters stacked for 240v, would that allow me to supply both my SolarEdge inverters and avoid the interlocked breaker switch from grid to output? I'm also considering on the trailer, replacing the PV panels with something more modern (400w) and running one side through one charge controller and the other side through a different charge controller. I believe the current single charge controller wouldn't support a single array that large, but maybe I'm wrong. I'm going to need to find someone to help me with this project. I have experience wiring my own house, and I have done many simple PV systems but this is a little out of my scope of expertise.
 

Hedges

I See Electromagnetic Fields!
Joined
Mar 28, 2020
Messages
11,005
@Hedges, I had the same question for the SMA support staff. Why would a slave error out on a temp sensor that is connected to the master? They said they were connected and if it was faulty it could trip the slave, but I really don't know. I suspect the unit is totally fine. I sent them the downloaded sd card and they just sent me an entire replacement on a pallet to my house.

On that note, I'm assuming that I can't swap SD cards on the new unit but need to go through the setup process, but I wanted to see if you knew the answer to that.
If you replaced the slave, just commission new inverter as slave #1.
It does need to be same version firmware (I think). I suggest backing up a copy of whatever new version it has, and whatever older version other one has. You can always get latest version from their website, but getting older ones may be difficult.

My local power supplier is single phase for residential which is unfortunate because 3phase with three inverters would be a no brainer. If I can get the one inverter to work, I will likely add another inverter to make a 2phase4 setup.

I've tried to figure out how to feed two of three Sunny Island from single-phase, and I might be able to make it work while connected, but can't figure out how to have the grid qualified as "good" for transition from off-grid to on-grid. If we could connect 4 inverters for 3 phase (two on one phase) we'd get 112A input, but don't think 3-phase-4 is supported.

It also doesn't look like multi-cluster supports backfeed of grid, or split-phase.

VFD is good for running 3-phase motors. Would be better with 3-phase input. But, I find it upsets Sunny Boy. I haven't come up with a simple work-around. Motor-generator before VFD should work. 1.0 PF front-end is what we want, but isn't built into my little unit.

If I had 4 SMA 6048 inverters stacked for 240v, would that allow me to supply both my SolarEdge inverters and avoid the interlocked breaker switch from grid to output?

I think two of your Solar Edge inverters, if they have enough PV panels, could exceed 56A through the relay. Perhaps their max output could be set lower to avoid that issue. If one has an array oriented SW and the other has array SE, peak wattage should be low enough to fit. But then, I'd want to over-panel them each to full output with extended hours of production by paralleling a SW string and a SE string.

With 2s2p, up to 112A per phase supported, 26.8 kW through the relays (but only if current is perfectly balanced.) QO270 breaker caused me a problem. Schneider 63A dual-pole DIN rail breakers are working for me.

You could go up to PV wattage 2x Sunny Island wattage, half on Sunny Island all the time and half straight to grid when grid is up, switched to Sunny Island when grid is down and manually disconnected from Sunny Island.

I'm also considering on the trailer, replacing the PV panels with something more modern (400w) and running one side through one charge controller and the other side through a different charge controller. I believe the current single charge controller wouldn't support a single array that large, but maybe I'm wrong. I'm going to need to find someone to help me with this project. I have experience wiring my own house, and I have done many simple PV systems but this is a little out of my scope of expertise.

Get the watts vs. battery voltage vs. PV voltage chart from Midnight's website.

For both SCC and GT PV inverters, consider paralleling strings of different orientations. You can over-panel about 40% without clipping peak production.

You have a generator. You may want grid normally fed to SI, with transfer switch for generator. Make sure there is 5 seconds both disconnected in between, so UL-1741 inverter backfeeding doesn't suddenly see out of phase input, has shut off before other source connected.
 

Hedges

I See Electromagnetic Fields!
Joined
Mar 28, 2020
Messages
11,005
@Hedges, I had the same question for the SMA support staff. Why would a slave error out on a temp sensor that is connected to the master? They said they were connected and if it was faulty it could trip the slave, but I really don't know. I suspect the unit is totally fine. I sent them the downloaded sd card and they just sent me an entire replacement on a pallet to my house.

Master reads analog sensor, might send digital data to slave. Instead, I would expect it to send adjusted charge voltage. I wouldn't have though analog circuitry of slave would come into play. Possibly support staff don't think. But we haven't thought of what could explain the fault. Maybe a communication error? But wouldn't expect that to repeatedly cause same fault, just random errors. Each has 2 RJ-45 jacks. Cable daisy-chains, ends get terminators. Could swap which jack gets which. Short cable run, if bad contact to terminator on one end (instead of bad contact to cable), might not matter much for a low-speed bus. New inverter would have come with spare sensor, spare cable, spare terminators.

You could try commissioning the old one by itself with its own temperature sensor, 1phase1. See how it works.
 

abilityonline

New Member
Joined
Feb 8, 2022
Messages
31
I think two of your Solar Edge inverters, if they have enough PV panels, could exceed 56A through the relay. Perhaps their max output could be set lower to avoid that issue. If one has an array oriented SW and the other has array SE, peak wattage should be low enough to fit. But then, I'd want to over-panel them each to full output with extended hours of production by paralleling a SW string and a SE string.
My two SolarEdges are configured with
inverter 1 with 21 PV with South Facing exposure
inverter 2 with 7 PV South, 14 East, 6 West

Inverter 1 output yearly is 985 kWh
Inverter 2 output yearly is 665 kWh

I know when we installed my PV system, we intentionally left plenty of load margin off each inverter. If I use the month of June as a max out scenario this is what I see. Am I calculating this correctly? I'll stop bothering you. I don't want to take advantage of your generosity. Thank you again.

Here is what I show. Am I calculating correctly if AC Power is 2.5kW and AC Voltage is 244v =10amps?1644514850008.png
1644515071785.png
 

Hedges

I See Electromagnetic Fields!
Joined
Mar 28, 2020
Messages
11,005
No problem, I like helping others make use of Sunny Island too.

The multiple angles should help reduce peak, possibly below relay pass-through limit.
If current ever slightly exceeds 56A, I think Sunny Island might open the relay. Then would probably close again 5 minutes later. Repeated cycling could be a problem.
If it doesn't open on excess export current, only deals with that for excess import, I don't think a very slightly high current would cause harm. Very high like 20kW and 90A would.

Probably, what you've got fits with two SI. No benefit from 4 SI unless you want higher than 11.5kW continuous draw at night (or if you add PV capacity). So if you can get 3rd SI working it can be a spare.

It would be nice to add panels and allocate so each inverter has fairly uniform production over the day.
Does SolarEdge have 3 MPPT inputs? Or are you relying on optimizers to match current from panels with 45 degree (or 90 degree?) orientation differences? I think their current boost is fairly limited.
 

abilityonline

New Member
Joined
Feb 8, 2022
Messages
31
No problem, I like helping others make use of Sunny Island too.

The multiple angles should help reduce peak, possibly below relay pass-through limit.
If current ever slightly exceeds 56A, I think Sunny Island might open the relay. Then would probably close again 5 minutes later. Repeated cycling could be a problem.
If it doesn't open on excess export current, only deals with that for excess import, I don't think a very slightly high current would cause harm. Very high like 20kW and 90A would.

Probably, what you've got fits with two SI. No benefit from 4 SI unless you want higher than 11.5kW continuous draw at night (or if you add PV capacity). So if you can get 3rd SI working it can be a spare.

It would be nice to add panels and allocate so each inverter has fairly uniform production over the day.
Does SolarEdge have 3 MPPT inputs? Or are you relying on optimizers to match current from panels with 45 degree (or 90 degree?) orientation differences? I think their current boost is fairly limited.
It appears they use power optimizers https://www.solaredge.com/us/products/power-optimizers#/
 

abilityonline

New Member
Joined
Feb 8, 2022
Messages
31
Hedges: This is my first attempt, feeble as it may be to try to illustrate what I would need to do. Could you tell me how close or more likely how far off I am on this diagram?
1644638391864.png
 

Hedges

I See Electromagnetic Fields!
Joined
Mar 28, 2020
Messages
11,005
Hedges: This is my first attempt, feeble as it may be to try to illustrate what I would need to do. Could you tell me how close or more likely how far off I am on this diagram?

It says "Non-interlocked UL-1741 backfeed" at 225A panel, wired to "240V" of 2x SI-6048.
Other side of 2x SI has breaker box, battery, PV, Midnight controller, Generator.

It is important to keep the two AC connections of SI-6048 straight:
"AC1 (Loads/Sunny Boys)" (This must never be connected to the grid, will fight and lose. Or electrocute a lineman.)
"AC2 (Generator/Grid)"

You don't show the addition of a transfer switch. Without a transfer switch, you could disconnect generator from AC2 and instead connect wire to breaker in 225A panel, then change SI setup to "grid" something or other. If battery gets low, Sunny Island will draw from grid to charge battery. If "sell" is enabled, if Midnight charges battery higher than target voltage SI is looking for, it will export to grid. The only things battery backed up are what's on the panel of the trailer. If grid goes down, SI detects that and disconnects from grid.

If you put an interlocked backfeed breaker in 225A panel, then you could connect AC1 to it. Manually disconnect 225A from 400A main panel, connect Sunny Islands. They will then interact with Solar Edge and keep the 225A going on batteries.

Either way, your "critical loads" panels on 400A will never be battery backed up. Leave 400A panel for high power loads only the grid will ever feed.

I suggest disconnect generator, put 70A dual pole breaker in 400A panel, feed that to AC2 of Sunny Island.

Feed AC1 of Sunny Island through an interlocked backfeed breaker to 225A panel (interlocked so you can bypass Sunny Island for repair.)
The 225A panel can be your "critical load" panel, never shut off. It has SolarEdge connected, and any low-power communication or alarm equipment.

Put another breaker in 225A panel, feed through a "load-shed" relay to an "important loads" panel. That's what is normally battery backed up, but will get disconnected at 70% DoD.

You can have other panels normally fed by 400A panel, not automatically battery backed up, workshop for instance. With interlocked breaker, they could instead be manually switched to Sunny Island (should fed from some load-shed circuit, whether same relay or one with different SoC switchpoint).




Logically, the breaker box on trailer could serve instead of new 225A panel, but it is too low amperage for code when being backfed. And, you should have a way to keep using Solar Edge if trailer is hauled off for work or something.
Because that (125A?) Homeline panel on trailer is too small to run PV current through (120% rule), probably put a 70A main breaker in it if it doesn't already have one, and tap off the wires between Sunny Island and 70A breaker (e.g. split bolts) for wire run to 225A panel where it lands on interlocked backfed 70A breaker.

I think 225A panel could get a 150A main breaker; 120% of 225A = 270A, 270A - 150A = 120A allowed for PV breakers. I'm guessing breakers for Solar Edge are too large for a 200A breaker to be allowed by 120% rule.
 

abilityonline

New Member
Joined
Feb 8, 2022
Messages
31
It says "Non-interlocked UL-1741 backfeed" at 225A panel, wired to "240V" of 2x SI-6048.
Other side of 2x SI has breaker box, battery, PV, Midnight controller, Generator.

It is important to keep the two AC connections of SI-6048 straight:
"AC1 (Loads/Sunny Boys)" (This must never be connected to the grid, will fight and lose. Or electrocute a lineman.)
"AC2 (Generator/Grid)"

You don't show the addition of a transfer switch. Without a transfer switch, you could disconnect generator from AC2 and instead connect wire to breaker in 225A panel, then change SI setup to "grid" something or other. If battery gets low, Sunny Island will draw from grid to charge battery. If "sell" is enabled, if Midnight charges battery higher than target voltage SI is looking for, it will export to grid. The only things battery backed up are what's on the panel of the trailer. If grid goes down, SI detects that and disconnects from grid.

If you put an interlocked backfeed breaker in 225A panel, then you could connect AC1 to it. Manually disconnect 225A from 400A main panel, connect Sunny Islands. They will then interact with Solar Edge and keep the 225A going on batteries.

Either way, your "critical loads" panels on 400A will never be battery backed up. Leave 400A panel for high power loads only the grid will ever feed.

I suggest disconnect generator, put 70A dual pole breaker in 400A panel, feed that to AC2 of Sunny Island.

Feed AC1 of Sunny Island through an interlocked backfeed breaker to 225A panel (interlocked so you can bypass Sunny Island for repair.)
The 225A panel can be your "critical load" panel, never shut off. It has SolarEdge connected, and any low-power communication or alarm equipment.

Put another breaker in 225A panel, feed through a "load-shed" relay to an "important loads" panel. That's what is normally battery backed up, but will get disconnected at 70% DoD.

You can have other panels normally fed by 400A panel, not automatically battery backed up, workshop for instance. With interlocked breaker, they could instead be manually switched to Sunny Island (should fed from some load-shed circuit, whether same relay or one with different SoC switchpoint).




Logically, the breaker box on trailer could serve instead of new 225A panel, but it is too low amperage for code when being backfed. And, you should have a way to keep using Solar Edge if trailer is hauled off for work or something.
Because that (125A?) Homeline panel on trailer is too small to run PV current through (120% rule), probably put a 70A main breaker in it if it doesn't already have one, and tap off the wires between Sunny Island and 70A breaker (e.g. split bolts) for wire run to 225A panel where it lands on interlocked backfed 70A breaker.

I think 225A panel could get a 150A main breaker; 120% of 225A = 270A, 270A - 150A = 120A allowed for PV breakers. I'm guessing breakers for Solar Edge are too large for a 200A breaker to be allowed by 120% rule.
Thank you again Hedges. This is my next stab at this, I'm hoping I am a little closer but probably still have errors. If you have a moment to correct and instruct, again, I express my gratitude.
 

Attachments

  • Screenshot_20220212-145739_Samsung Notes.jpg
    Screenshot_20220212-145739_Samsung Notes.jpg
    321.2 KB · Views: 7

Hedges

I See Electromagnetic Fields!
Joined
Mar 28, 2020
Messages
11,005
You still have "critical loads" panels hanging off 400A panel. You haven't found a way to interlock/backfeed 400A panel. You could put interlocks in the critical loads panels and switch them to be powered by Sunny Island.

"ATS" automatic transfer switch?
Sunny Island internally will connect AC2 when power is good, disconnect when it is bad.
In the location you've shown, you could have an automatic or manual transfer switch to select either grid or generator feeding AC2.
It would be best if the switch disconnected both sources for 5 seconds before reconnecting. A UL-1741 inverter (and SMA in particular according to their documentation) must not be slammed between two AC sources. It could connect 180 degrees out of phase and present a short to the source, so it would be damaged. A digital input of SI must be used to indicate when generator is connected, so SI will tolerate sloppy voltage/frequency and won't let PV backfeed.

AC1 to 225A panel with interlock looks good. That can also be "critical loads" panel, things like phone/internet which will be powered to the last gasp of the batteries (80% DoD).

You could take an output breaker from 225A panel, feed it through load-shed relay (that's "relay", not "breaker"), and wire output of load-shed relay to "important loads". Those loads would be battery backed up down to 70% DoD.

Generator Start is default for first signaling relay of Master SI. "Above 70% DoD keep load-shed relay closed" is default for second signaling relay of Master. Two more in Slave; you can program one as a second "shed" and have "less important loads" disconnected. Or use it directly for A/C thermostat signal.

The signaling relay can switch 120VAC, 240VAC, or 48VDC. There are PTC fuse protected "48V" (battery) an return terminals. PTC trips at something like 0.5A or 1.0A. AC relays are relatively low current when closed (magnetic circuit completed by pulling in pole piece. DC relays are not, and can dissipate a lot of power. There are various "economizer" schemes to draw high current during pull-in, less to hold.

I bought the SMA branded 3PST 100A relay. I think it is made by ABB? It has two coils in series, one low resistance for pull-in, other high resistance for hold. The pull-in relay measured 10 ohms, so at 50V, 5A (!) draw. That's 250W! After it slams shut, an extra contact opens, so high resistance coil is in series, dropping current very low. PTC fuses tolerate that, since they have a thermal time-constant.

You've probably seen this block diagram:


What it doesn't show is breaker panels for Sunny Boys, or load-shed relay. Also doesn't label AC1, AC2.

"Main", "Secondary" Sunny Island - I think SMA is "Woke" :ROFLMAO:
They can change their glossy brochure, but the original designation is immortalized in firmware.
 

abilityonline

New Member
Joined
Feb 8, 2022
Messages
31
Hedges: As I replace this faulty slave inverter, how many settings do I need to specify in the quick startup? If the slave is getting all its orders from the master, do I just need to designate it as a slave or do I need to specify led acid battery, size of battery, 48v, etc.? Also if each battery bank is 496 ah, do I specify ah as 496 or 992ah?
 
Last edited:

Hedges

I See Electromagnetic Fields!
Joined
Mar 28, 2020
Messages
11,005
I think you could just power down, install new inverter, configure it as slave #1, restart master. Everything else should be unchanged.

But it may be necessary to get both on same version of firmware, so check that first. Seems likely latest unit shipped by SMA would have different rev from several year old DC Solar unit. I suggest finding a way to back up old one first. There may be an explicit command to sweep code to slaves. Or, maybe it happens automatically. I can't remember, RTFM. I've never done anything except store history to SD card for SMA debug, following their step-by-step instructions.

You could walk through the "new system" process, just noting values and not changing any. Amp hours would be total of all batteries in parallel.

Other interesting experiments could be to commission replacement inverter as new master, see how slave behaves with it (which really had the problem, master or slave?) Another, commission faulty slave as master, master as slave. Of course, you might be overwriting previous settings and history, so write everything down and see if you can store to SD card, maybe transfer to PC. I happened to have a laptop with large SD slot. I've bought more (for Sunny Web Box), had to find old stock of correct capacity and format.
 

abilityonline

New Member
Joined
Feb 8, 2022
Messages
31
I think you could just power down, install new inverter, configure it as slave #1, restart master. Everything else should be unchanged.

But it may be necessary to get both on same version of firmware, so check that first. Seems likely latest unit shipped by SMA would have different rev from several year old DC Solar unit. I suggest finding a way to back up old one first. There may be an explicit command to sweep code to slaves. Or, maybe it happens automatically. I can't remember, RTFM. I've never done anything except store history to SD card for SMA debug, following their step-by-step instructions.

You could walk through the "new system" process, just noting values and not changing any. Amp hours would be total of all batteries in parallel.

Other interesting experiments could be to commission replacement inverter as new master, see how slave behaves with it (which really had the problem, master or slave?) Another, commission faulty slave as master, master as slave. Of course, you might be overwriting previous settings and history, so write everything down and see if you can store to SD card, maybe transfer to PC. I happened to have a laptop with large SD slot. I've bought more (for Sunny Web Box), had to find old stock of correct capacity and format.
Hedges, thankyou. If I were to try to designate the current slave as master and current master as slave, are the Master and slave interchangeable or would I have to reroute any wire or cables, besides the battery sensor from the old master to the new master?
 

Hedges

I See Electromagnetic Fields!
Joined
Mar 28, 2020
Messages
11,005
Only differences I know are that master requires thermocouple (but both could have one, and you should have a spare now). And, if you use RS-485 to Sunny Boys, that goes to master. Could be true of any data connection, although someone was told when talking to Data Manager all Sunny Islands required a daughter card. (I would have though every cluster required a daughter card only in the master.)
 

abilityonline

New Member
Joined
Feb 8, 2022
Messages
31
Hedges: The good news. I replaced the old slave that had the tempsensor error. Added the old SD card, ran setup and designated it as S1 and everything works like a champ. I did some research and found someone who got further in the support conversation with SMA and they said their issue with that error was the result of a break in the Inverter's HeatSink /Transformer temperature sensor. So the question I have is what to do with this faulty unit, they didn't ask for it back. Wondering if it is possible to source this sensor and solder it on. Or if the unit was used in a lithium-ion setup where battery temp is coming from a BMS if it would work without issue in that environment.
 

Hedges

I See Electromagnetic Fields!
Joined
Mar 28, 2020
Messages
11,005
Makes more sense that slave had problem with temperature sensor for electronics, not for battery.
Lead-acid, master uses battery temperature sensor. Lithium, it gets data from BMS.

Maybe there is a thermistor on the heatsink for power transistors, and you could replace it. Or transformer, you said. That may be in the "Opticool" cavity, less accessible. Maybe thermistor is wrapped in transformer's tape. But if both thermally connected, probably near transistors. Most common is 10k ohm (at room temperature) NTC thermistor (but they do have varying temperature coefficients.) You can probably determine value from a good unit to be sure, maybe measured hot and then after cooled to room temperature.
 
Top