New SW and XW communication "Conext ComBox
Comments
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Re: New SW and XW communication "Conext ComBoxAccording to the manual, that is how it is supposed to work by design. When grid comes back from an outage, it starts a new cycle. Inverter always has priority over solar charger. May be not the best design, but it works as documented.
The grid coming back from an outage would be just like me starting up our little Champion generator, wouldn't it? The Charger Block keeps the XW from using the charger with our little generator. If there's incoming RE power it will use that above the Grid Support Volts and support our little generator though.
But what Joe is saying is that if I have a XW-MPPT60 controller, the inverter charger is enabled, and I start the generator - it will shut down my solar and use the generator to charge the batteries?
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Chris -
Re: New SW and XW communication "Conext ComBoxChrisOlson wrote: »But what Joe is saying is that if I have a XW-MPPT60 controller, the inverter charger is enabled, and I start the generator - it will shut down my solar and use the generator to charge the batteries?
Yes. That's exactly what it would do. Both solar and generator would charge batteries during bulk. As soon as absorption is reached, MPPT60 would start dialing down while XW6048 would go full force. It would go full force until MPPT60 production is zero, then MPPT60 would be kept at zero and XW6048 would start dialing current down to keep the absorption voltage. -
Re: New SW and XW communication "Conext ComBoxYes. That's exactly what it would do. Both solar and generator would charge batteries during bulk. As soon as absorption is reached, MPPT60 would start dialing down while XW6048 would go full force. It would go full force until MPPT60 production is zero, then MPPT60 would be kept at zero and XW6048 would start dialing current down to keep the absorption voltage.
With an off-grid installation, if you have your generator charging batteries on AC2, does it do the same thing on AC2 input?
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Chris -
Re: New SW and XW communication "Conext ComBoxChrisOlson wrote: »With an off-grid installation, if you have your generator charging batteries on AC2, does it do the same thing on AC2 input?
Yes. Doesn't matter much to me most of the time because I hardly ever run the genrator during solar production. -
Re: New SW and XW communication "Conext ComBoxYes. Doesn't matter much to me most of the time because I hardly ever run the genrator during solar production.
That's pretty interesting. I would suppose they do that based on the fact that since the generator is running we'd better make the best use of the fuel being burned instead of letting it run partially loaded? But it seems it should be the other way around on AC1, and I suppose the same programming is used to operate the charger regardless of which AC power input the power is coming from.
I have noticed that when our generator starts on load amps, and when the load on it drops below the shutdown threshold, that the XW will switch the generator to charging for the one minute while it monitors the load to see if it's coming back or not. During that minute the XW's charger will most times overpower our Classics and make them cut back too. And the Classics do not communicate with the XW at all via Xanbus.
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Chris -
Re: New SW and XW communication "Conext ComBoxChrisOlson wrote: »I have noticed that when our generator starts on load amps, and when the load on it drops below the shutdown threshold, that the XW will switch the generator to charging for the one minute while it monitors the load to see if it's coming back or not. During that minute the XW's charger will most times overpower our Classics and make them cut back too. And the Classics do not communicate with the XW at all via Xanbus.
I didn't try to run my SCCs disconnected from the XanBus, but I think it might be more or less random. When chargers measure battery voltage, the measurement always has an error. If a charger thinks the voltage is higher, it'll dial down. If a charger tends to think that the voltage is mrginally less than it is, it will dominate. Adjusting charging voltage by 0.1V up in your classics may make them dominant over your XW. -
Re: New SW and XW communication "Conext ComBox
Yes, but for us it's only one minute usually during the time the inverter is deciding whether or not to disconnect the generator and shut it down. So I haven't gotten too exited about it. I really like to keep the charge stage voltages the same in all my equipment to eliminate confusion.
The Classics themselves are networked so every controller is always in agreement with the other ones. I bought a XW-MPPT60 controller but am not using it at present because it wouldn't agree with the Classics on what the charge stage was. I really like the Classic controllers because they are more sophisticated, with much higher capacity than the MPPT60. But I'm thinking about putting solar on our yacht and I might use the MPPT60 for that, besides buying a Xantrex inverter for the boat that will have AGS for our onboard generator and the SCP on Xanbus. I think for that the XW-MPPT60 will work very nicely, so I hung onto it instead of selling it.
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Chris -
Re: New SW and XW communication "Conext ComBoxIf I enable the charger, then it will always try to charge from the grid in spite of adequate solar. My grid glitches several times a day, if I leave the charger enabled, when the grid gets requalified, it will begin a bulk cycle from the grid and shut off the solar controllers.
Hi Joe,
Maybe tell me what I did wrong here.
I disabled the Charger Block (so the charger works on AC1). I set Grid Support to ENABLED. I set the Grid Support Volts to 48.0. I enabled Load Shaving by setting the start time to 0:01 and the end time to 0:00, so Load Shaving is active all except for one minute past midnight. I set the Load Shaving Amps to 0.
I made sure Sell is DISABLED so it don't burn the windings or AVR out of our little generator.
I made sure we had no big loads on, or anything that's going to come on as a surprise. I started our little Champion backup generator. It almost immediately qualified on AC1 and accepted load in AC Pass Thru. During that first five minutes, whenever I run it, we have to be careful to not turn on anything big because the inverter won't support it on AC1. For some reason it takes the Load Shaving that amount of time to work. After a five minute delay the SCP said Grid Support mode on it and the load came off our little Champion and the loads went to wind and solar power.
I checked the leads from the Trace T240 (the gen is only 120V so I have to use a transformer on it) and XW was drawing .1 amp on L1 and .4 amps on L2 @ 123V. This agreed exactly with what the SCP said for AC1 input - 63 watts. I then flipped on the breakers to some of our heavier loads, that I had turned off to prevent getting the little generator spit off. The total load on the inverter went up to 4,760 watts (water heater was operating on two elements). The amount of draw on AC1 went to 1.3 amps on L1 and 2.7 amps on L2 - 488 watts shown on the SCP, which again agrees with the readings on my Fluke meter from the gen's transformer.
After awhile one of the water heater elements kicked out so the load dropped to 2,410 watts. I rechecked the AC1 input - .4 amps on L1 and .5 amps on L2 - 111 watts shown on the SCP for AC1 input, which again agrees with the Fluke.
Next, I shut off the breaker to the little generator to disconnect it (simulate a grid outage). This generated an Automatic Fault (A1 - under frequency). I waited about 5-10 minutes and reconnected the little generator. It almost immediately qualified and when it accepted load it just about got spit off. But I got AC1 Breaker Size set to 10 amps so the inverter, instead of waiting the five minutes, switched to Grid Support mode right away to help the gen out and it took just about all the load off it and it was fine. It did NOT charge the batteries even though I had the Charger Block disabled, when I reconnected the little gen. When you have Load Shaving enabled it won't use the charger on AC1 unless the battery voltage drops to LBCO +1V.
Normally I set that Load Shaving to a higher value of 10 amps (identical to the AC1 Breaker Size) and this lets the system load the generator to about 2,400-2,500 watts, but only when the voltage is below 48.0 in Load Shaving. Otherwise it uses Grid Support based on the AC1 Breaker Size and it won't let the load on AC1 exceed that. But because it's support mode, and not a transfer mode, it has to draw a token amount of power from the AC1 input in order to support it. And based on my measurements that appears to be roughly 10% of the total load.
I think there's a misconception here that just because you have excess RE power available, does NOT mean the inverter is going to disconnect the AC1 input and not use it. The key is that it's a support mode, not a transfer mode. In order to support the AC1 input source it has to use it at all times. That's a limitation of the hardware. Otherwise you'd have to have a relay click in there and disconnect it - THEN you have a transfer mode.
In conclusion I cannot find a confounded thing wrong with the way it works. Not a single glitch, no bugs - it worked flawless even with our little underpowered Champion. And I learned something new - now that I know that enabling the Load Shaving prevents the charger from working on AC1 unless the voltage drops to LBCO +1V I'm going to use that instead of the Charger Block to keep the charger from being activated when we're running our little backup gen
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Chris -
Re: New SW and XW communication "Conext ComBoxChrisOlson wrote: »Hi Joe,
Maybe tell me what I did wrong here.
I disabled the Charger Block (so the charger works on AC1). I set Grid Support to ENABLED. I set the Grid Support Volts to 48.0. I enabled Load Shaving by setting the start time to 0:01 and the end time to 0:00, so Load Shaving is active all except for one minute past midnight. I set the Load Shaving Amps to 0.
I made sure Sell is DISABLED so it don't burn the windings or AVR out of our little generator.
I made sure we had no big loads on, or anything that's going to come on as a surprise. I started our little Champion backup generator. It almost immediately qualified on AC1 and accepted load in AC Pass Thru. During that first five minutes, whenever I run it, we have to be careful to not turn on anything big because the inverter won't support it on AC1. For some reason it takes the Load Shaving that amount of time to work. After a five minute delay the SCP said Grid Support mode on it and the load came off our little Champion and the loads went to wind and solar power.
The five minutes is the anti islanding delay for grid support, this is normal.
My system operates similarly, you told the load shaving algorithm to draw zero amps from the grid (load shave = 0) but is drew a proportional amount from the grid. I dont run big loads like your water heater but I typically see a 70 - 30 percent split. I understand that the inverter has to draw some power from the grid but IMHO if load shave was working, the grid draw would remain around 63 watts no matter what the load (providing your bank is up to is and it stays in load shave mode).
I checked the leads from the Trace T240 (the gen is only 120V so I have to use a transformer on it) and XW was drawing .1 amp on L1 and .4 amps on L2 @ 123V. This agreed exactly with what the SCP said for AC1 input - 63 watts. I then flipped on the breakers to some of our heavier loads, that I had turned off to prevent getting the little generator spit off. The total load on the inverter went up to 4,760 watts (water heater was operating on two elements). The amount of draw on AC1 went to 1.3 amps on L1 and 2.7 amps on L2 - 488 watts shown on the SCP, which again agrees with the readings on my Fluke meter from the gen's transformer.
After awhile one of the water heater elements kicked out so the load dropped to 2,410 watts. I rechecked the AC1 input - .4 amps on L1 and .5 amps on L2 - 111 watts shown on the SCP for AC1 input, which again agrees with the Fluke.
Next, I shut off the breaker to the little generator to disconnect it (simulate a grid outage). This generated an Automatic Fault (A1 - under frequency). I waited about 5-10 minutes and reconnected the little generator. It almost immediately qualified and when it accepted load it just about got spit off. But I got AC1 Breaker Size set to 10 amps so the inverter, instead of waiting the five minutes, switched to Grid Support mode right away to help the gen out and it took just about all the load off it and it was fine. It did NOT charge the batteries even though I had the Charger Block disabled, when I reconnected the little gen. When you have Load Shaving enabled it won't use the charger on AC1 unless the battery voltage drops to LBCO +1V.
Here is where our systems differ, if I have charger block disabled and AC1 has to go through a qualification cycle from an interruption, as soon as AC1 is qualified, the grid charger goes into a bulk cycle even if the battery bank voltage is above recharge volts. This is my primary issue. It states in the manual:
During the charger block period, no charging on AC1 occurs even if the batteries
discharge below ReCharge Volts setting. However, a generator connected to
AC2 (in the absence of utility/AC1 power) or a Xantrex XW Solar Charge
Controller may charge batteries during the charger block period. AC priority must
be set to AC2 to charge batteries with a generator connected to AC2 during the
charger block period.
The other thing that the system does is if charger block is active, it will not charge from AC2 no matter what. These operational issues have been confirmed by tech support and according to them, they are working on a new firmware release to correct these issues.
Normally I set that Load Shaving to a higher value of 10 amps (identical to the AC1 Breaker Size) and this lets the system load the generator to about 2,400-2,500 watts, but only when the voltage is below 48.0 in Load Shaving. Otherwise it uses Grid Support based on the AC1 Breaker Size and it won't let the load on AC1 exceed that. But because it's support mode, and not a transfer mode, it has to draw a token amount of power from the AC1 input in order to support it. And based on my measurements that appears to be roughly 10% of the total load.
I typically see more like 30% unless my battery is right up to 100%
I think there's a misconception here that just because you have excess RE power available, does NOT mean the inverter is going to disconnect the AC1 input and not use it. The key is that it's a support mode, not a transfer mode. In order to support the AC1 input source it has to use it at all times. That's a limitation of the hardware. Otherwise you'd have to have a relay click in there and disconnect it - THEN you have a transfer mode.
Well I think you have to agree with me that if you have 2.5KW of solar available and AC1 glitches, the system should not default to drawing several KW of power from the grid and shut down the solar to recharge things. I am simply saying that the state machine that controls the charging source priorities is faulty. If a networked SCC is present and capable of producing, it should be used before defaulting to 100% grid power.
In conclusion I cannot find a confounded thing wrong with the way it works. Not a single glitch, no bugs - it worked flawless even with our little underpowered Champion. And I learned something new - now that I know that enabling the Load Shaving prevents the charger from working on AC1 unless the voltage drops to LBCO +1V I'm going to use that instead of the Charger Block to keep the charger from being activated when we're running our little backup gen
Well Chris, I pretty much gave up and called tech support back when I found that this thing was not doing what the manual said it should. I never explored messing around with LBCO and load shaving. When I get some free time and the conditions are right, I will give your method a shot and see what happens. I am not sure that the tech support guys at Schneider know about this one.
Joe--
Chris -
Re: New SW and XW communication "Conext ComBoxWell Chris, I pretty much gave up and called tech support back when I found that this thing was not doing what the manual said it should. I never explored messing around with LBCO and load shaving. When I get some free time and the conditions are right, I will give your method a shot and see what happens. I am not sure that the tech support guys at Schneider know about this one.
Well, I thought I'd play with it and see what it does. Frankly, having that Sell feature in there scares me with a generator. When I reviewed the settings for that it appears that if I would inadvertently set something wrong it could backfeed my little generator with more amps than the windings could even take and blow the gen head right off the frame or torch the AVR before the breaker could trip. For off-grid I wish they had an option to switch AC1 to a second gen input so all that stuff would be disabled and not even in the menu.
I'm not sure I still totally understand it. But it appears that when it's in Grid Support mode (that's what it says on the SCP Home Screen) that it draws a split with some power from the gen and the bulk from the RE system. When voltage drops below the Grid Support Volts it then switches to Load Shaving and still draws a token amount of power from the gen that doesn't really appear to be any different than Grid Support Mode?
It actually works well with our little generator because we WANT to use the gen - that's why we're running it. It supports the generator very nicely and prevents it from getting spit off due to overload. I would have to put on a different hat to look at it from the standpoint of having grid power and NOT wanting to use the grid to maximize your solar harvest. But I don't know that I can simulate that with our little generator because if we would turn on a large load that a true grid input would not have a problem with before the inverter adjusted the ratio, our little gen just gets spit off. It HAS to be in that Support Mode or our little generator just don't work. That's why I set the Grid Support Volts so low.
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Chris -
Re: New SW and XW communication "Conext ComBoxI understand that the inverter has to draw some power from the grid but IMHO if load shave was working, the grid draw would remain around 63 watts no matter what the load (providing your bank is up to is and it stays in load shave mode).
It cannot be that precise. It does its best to prevent backfeeding to the grid. Given its measurement devices, it does very good job at keeping the draw from the grid low.
The solution to this problem would be to disconnect the grid (as if it wasn't qualified) and not use it at all unless there's a need. However, the software dosn't let you do that. There's no way to set it up to only use a grid to charge batteries when needed (same as you would use a generator off-grid). -
Re: New SW and XW communication "Conext ComBoxThe solution to this problem would be to disconnect the grid (as if it wasn't qualified) and not use it at all unless there's a need.
The old SW Plus would do that if you set it up for BX Mode. But it was glitchy because there was a momentary "blink" in the power when it did it. I think the XW designers tried to come up with a system that eliminates that "glitch" by using Support Modes instead of TXFR Modes.
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Chris -
Re: New SW and XW communication "Conext ComBox
It can be precise, it is just lousy firmware that is slow. With sell disabled in grid support mode, If I have a large load swing on the inverter, The instability WILL cause some power to be fed back on the grid momentarily.It cannot be that precise. It does its best to prevent bacfeeding to the grid. Given its measurement devices, it does very good job at keeping the draw from the grid low.
The solution to this problem would be to disconnect the grid (as if it wasn't qualified) and not use it at all unless there's a need. However, the software dosn't let you do that. There's no way to set it up to only use a grid to charge batteries when needed (same as you would use a generator off-grid).
That is exactly how I run mine. I use a Victron battery monitor to drive a contactor. When the batteries get up to about 90%, I go completely off grid. When the batteries get down to about 80%, I reconnect and run in grid support. Of course, I adjust the percentages as the seasons change. In the winter, I am rarely completely off grid. -
Re: New SW and XW communication "Conext ComBoxIt can be precise, it is just lousy firmware that is slow. With sell disabled in grid support mode, If I have a large load swing on the inverter, The instability WILL cause some power to be fed back on the grid momentarily.
Are you sure about that? I have NEVER noted that when running our little generator because it would wreak all holy havoc with the gen.
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Chris -
Re: New SW and XW communication "Conext ComBoxThe instability WILL cause some power to be fed back on the grid momentarily.
That's bad. I haven't tried it myself, but as I remember tech support told me that it won't backfeed to the grid if the sell mode is disabled. I decided that I'd better not risk it, and it turns out I was right. -
Re: New SW and XW communication "Conext ComBoxChrisOlson wrote: »Are you sure about that? I have NEVER noted that when running our little generator because it would wreak all holy havoc with the gen.
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Chris
If grid support is enabled and the inverter is running at around 800 watts or so and a large load like my well pump comes on, the SCP indicates that power is being fed to the grid. Normally in grid support mode, the negative sign on the grid load indicates that it is using power FROM the grid and when the battery is near full, that number can be as mentioned around 70 watts. When my well pump comes on, the "bounce" in the loop will allow it to bounce into positive territory for a second or two. I have also seen this on the meters display.
When I spoke to tech support I was told that this was a normal phenomenon but it is real. For me it does not make much of a difference because it seems to be a transient related thing and it doesn't bother the grid and I am not sure that it would bother a generator much either since it would essentially unload the generator and maybe even make the head act like a motor for a brief second. -
Re: New SW and XW communication "Conext ComBoxFor me it does not make much of a difference because it seems to be a transient related thing and it doesn't bother the grid and I am not sure that it would bother a generator much either since it would essentially unload the generator and maybe even make the head act like a motor for a brief second.
It depends on how big the surge is. The generator has a rotating field with the intensity of the field set by the AVR. When you backfeed a generator it can induce a voltage and current spike in the field winding and exciter winding and smoke the AVR. Which is not good.
Now you got me scared again and I'm going to have to check this out because I'm afraid of smoking the head in my little Champion generator. If this is indeed the case I'll unwire it from AC1 and wire into another transfer switch that selects either the Honda or Champion on AC2.
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Chris -
Re: New SW and XW communication "Conext ComBox
There is probably a race between back driving current and driving the genset rpm out of frequency for the hybrid inverter.
-BillNear San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset -
Re: New SW and XW communication "Conext ComBoxThere is probably a race between back driving current and driving the genset rpm out of frequency for the hybrid inverter
I've spent the last hour or so trying to verify that it does that with my Fluke meter on capture using the Honda temporarily jumpered into the AC1. The Honda don't have an AVR, nor does it have an exciter winding, so it can't hurt that gen head. I haven't gotten it to backfeed even one milliamp by spiking it with various high-draw loads. It just seamlessly switches to supporting the generator from the batteries.
So there could be something wrong with Joe's inverter, or I'm not doing it right. But I think I'm satisfied that it doesn't backfeed the gen here the way I'm using it. The old SW Plus would sometimes backfeed its AC power source too, as a way to control over-DC voltage. That would sometimes trip the breaker on the Champion. But this XW is different because it has the capability to feed SERIOUS power back to its power source, and I needed to insure that it's not going to do that to my little Champion. A big surge would blow the AVR before the breaker tripped. And that would be bad.
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Chris -
Re: New SW and XW communication "Conext ComBoxChrisOlson wrote: »I've spent the last hour or so trying to verify that it does that with my Fluke meter on capture using the Honda temporarily jumpered into the AC1. The Honda don't have an AVR, nor does it have an exciter winding, so it can't hurt that gen head. I haven't gotten it to backfeed even one milliamp by spiking it with various high-draw loads. It just seamlessly switches to supporting the generator from the batteries.
So there could be something wrong with Joe's inverter, or I'm not doing it right. But I think I'm satisfied that it doesn't backfeed the gen here the way I'm using it. The old SW Plus would sometimes backfeed its AC power source too, as a way to control over-DC voltage. That would sometimes trip the breaker on the Champion. But this XW is different because it has the capability to feed SERIOUS power back to its power source, and I needed to insure that it's not going to do that to my little Champion. A big surge would blow the AVR before the breaker tripped. And that would be bad.
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Chris
Chris, It may be that some obscure combination of settings creates the problem. Let me ask you this, when you are running your generator feeding AC1 and you are in grid support mode, does the AC1 load reading jump all over the place? Tech support told me that the hunting was to "tug on the line" to verify grid impedance. Which resulted in the instability I am referring to. -
Re: New SW and XW communication "Conext ComBoxChris, It may be that some obscure combination of settings creates the problem. Let me ask you this, when you are running your generator feeding AC1 and you are in grid support mode, does the AC1 load reading jump all over the place? Tech support told me that the hunting was to "tug on the line" to verify grid impedance. Which resulted in the instability I am referring to.
Yep, it varies by some. But nothing radical that I can see. It depends on the load as to how much it pulls from the generator. But when our loads were running at 500-600 watts earlier the Fluke showed .2-.3 amps per leg on the gen and the SCP said 66 watts, varying by maybe 5 watts or so either way. When I threw on a big load (air compressor) it went to 2.05 kW load and the Fluke said .8 amps on L1 and .9 amps on L2. The SCP said 419 watts on the gen but it still varies by maybe 10 watts either way then.
Is that what you see too?
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Chris -
Re: New SW and XW communication "Conext ComBoxChrisOlson wrote: »Yep, it varies by some. But nothing radical that I can see. It depends on the load as to how much it pulls from the generator. But when our loads were running at 500-600 watts earlier the Fluke showed .2-.3 amps per leg on the gen and the SCP said 66 watts, varying by maybe 5 watts or so either way. When I threw on a big load (air compressor) it went to 2.05 kW load and the Fluke said .8 amps on L1 and .9 amps on L2. The SCP said 419 watts on the gen but it still varies by maybe 10 watts either way then.
Is that what you see too?
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Chris
No, I see much bigger perturbations. Right now my system is in grid support with a pretty full battery and the SCP AC1 load display is jumping between 130 and about 290. The load on the inverter is about 830 watts right now. Maybe my stuff is broken?? -
Re: New SW and XW communication "Conext ComBoxNo, I see much bigger perturbations. Right now my system is in grid support with a pretty full battery and the SCP AC1 load display is jumping between 130 and about 290. The load on the inverter is about 830 watts right now. Maybe my stuff is broken??
Gosh, I dunno. I think I would suspect your grid power before I'd suspect a problem in the inverter because I don't think it would work at all if the inverter was looney. Have you put a volt meter and freq meter on your grid power lately? You mention it "glitches" several times a day. That makes me highly suspect of your grid stability. Our Honda generator is VERY stable because it has an electronically controlled engine and voltage/freq regulation. Bad grid power could cause it, I think.
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Chris -
Re: New SW and XW communication "Conext ComBox
Just a thought: the transformer feeding Joe_B's house may be undersized. -
Re: New SW and XW communication "Conext ComBox
well, i think that's along the lines of why chris wanted him to check his utility power to see if it's alright. -
Re: New SW and XW communication "Conext ComBox
Yep, there is no question that my grid connection is relatively high impedance as grid connections go. It's funny but although I live out in the stix, there is a hydroelectric plant about 5 miles from here. I suspect that my glitches come from there but one of the reasons I put this system in was the grid crapping out regularly and for extended periods of time.
This may explain the difference between our two systems and also why the tech support folks say it is normal. I don't think my hardware is a problem since it seems to be working the same since day one and has not crapped out or degraded.
In any case, I have work around hardware in place to make things work the way I want it to so "it is what it is". I just got my latest energy survey from national grid and they tell me I am the second most efficient energy user out of 100 customers within a half of a mile, and the house across the street is vacant and I am happy with the $20 - $30 electric bill each month. -
Re: New SW and XW communication "Conext ComBox
Joe - I got everything hooked back up "normal" here now since I was fiddling around with generators this afternoon. So I went out and pulled the rope on the Champion and let it qualify. It hasn't been run much so I figured I'd run it an hour or so tonight anyway.
I think I might see what you're talking about.
I need to qualify what I did because I wanted to see your problem. I normally set the Grid Support Volts really high (60.0V) so the inverter uses Load Shave. That way it loads the little generator to what it can put out and supports it above its loading capability. But I set the Grid Support Volts to 52.0 for this because I suspect that's about what you might be using.
To review the settings I'm using - I got AC1 Breaker Size set to 10 amps (matches the little generator). I got Load Shaving set to 10 amps (also matches the little generator). Charger Block is disabled. Grid Support Volts is 52.0
We got about 600 watts of PV power coming in yet, and the turbines are shut down. Our bank is fully charged and in Float MPPT (below Float voltage but not to Rebulk voltage yet). Loads were .48 kW as shown on the info panel on the inverter. The SCP says it is operating in AC Pass Thru after it qualified the little generator, but it did the 300 second countdown on the display before it started Grid Support Mode.
While all this was taking place, the generator had assumed the loads, which took the load off the PV and batteries, so they popped right back up to Float (53.0), which is above the Grid Support Volts. So the thing went to Grid Support Mode and took the load off the generator and it was only putting out about 55 watts because the inverter took over most of the load. But that made the voltage drop to Load Shaving (below Grid Support Volts) and then the generator took over the load again while the voltage recovered back above the Grid Support Volts again. It kept doing this, varying all over the place and loading and unloading the generator. The only way I could get it to stop the yo-yo thing was to set the Grid Support Volts back up to 60.0 where I normally have it.
I had experimented earlier with the Grid Support Volts set to 48.0 (forcing it to use Grid Support Mode). But that don't use the generator at all unless there's a really big load on the system that exceeds the AC1 Breaker Size setting. This big swing starts to happen when the bank voltage is right around that Grid Support Volts setting, as far as I can see.
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Chris -
Re: New SW and XW communication "Conext ComBoxthey tell me I am the second most efficient energy user out of 100 customers within a half of a mile, and the house across the street is vacant and I am happy with the $20 - $30 electric bill each month.
Do you realize that it don't take a lot of PV power to generator $30 worth of electricity in a month anymore? Thrown in a little more PV capacity and disconnect from the utility. Then instead of being #2 most efficient on the block you can be an Outcast like me
Yeah, it'll work your batteries a little harder. But batteries are a "use 'em or lose 'em" thing anyway. And you might burn a little more gas in the Honda. But that will keep it from getting rusty
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Chris -
Re: New SW and XW communication "Conext ComBox
Chris,
First of all, I don't use load shave at all. Back when I got this system I saw some really strange behavior when load shave was enabled so I just never use it. I disconnect AC1 when I want to "load shave". But the instability that you described is similar to what I see on my SCP whenever I am in grid support mode. I will say that when I am not connected to the grid through AC1, my inverter readings are very stable +/- a few watts. As for my grid support voltage settings, I modify mine depending on the seasons and really have not seen a major effect on the instability issue. I am pretty convinced that I have a relatively high impedance grid connection and that really does have a major effect on how the loop hunts around. The next time I have occasion to speak with the tech support guys, I will get their thoughts on it.
What this discussion tells me is that there are indeed settings that can interact and cause varying degrees of loop instability in grid support modes. I think at this point I am going to just live with it and hope that this new firmware they are working on will solve some of the problems without creating any new ones. -
Re: New SW and XW communication "Conext ComBoxChris,
First of all, I don't use load shave at all
Oh, sorry about that. I didn't catch that part. As I found out yesterday, though, enabling the Load Shave feature effectively disables the charger on AC1 unless the battery would happen to discharge to LBCO +1V. It has not tried to use the charger at all on AC1 with all my fiddling around with it yesterday with that enabled, but it still works fine on AC2.
You could try setting the Grid Support Volts down to as low as it will go (48/24V), enable Load Shave, set the Load Shave Amps to a reasonable level that will take over loads if the battery would discharge to 48/24V, leave it run for a couple days without disconnecting it from the grid and see what it does. That will maximize your solar harvest I think by discharging the batteries a little deeper at night because it will be forced to support the grid 24 hours a day unless the battery would get below 48/24V where it would switch to Load Shave. That would minimize the use of Load Shaving and possibly prevent having to disconnect the inverter from the grid with your relay.
My tests show that it draws about 10% of the power from the grid/gen (AC1) when it's in Grid Support Mode with Load Shave enabled. You can limit the peak draw by setting the AC1 Breaker Size to the max you would want it to ever pull off the grid. So my theory is that if you generate 90% of your power from RE sources as it is now, it should work.
It should -
- fix the problem with the charger coming on on AC1 when the grid power comes back after a glitch
- prevent your MPPT60's from being shut down when they should be going full bore so you get maximum solar harvest
- cycle your batteries a little more (which I think they will like anyway)
- be fully automatic and your standby gen will take over and charge the batts on AC2 if the voltage falls below 48/24V for more than 2 hours - without having to use the battery monitor to disconnect it from grid power.
That's my theory, anyway, based on my fiddling around with it yesterday. It was actually quite educational because I learned some new things by messing with it
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Chris
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