Anotherpower.com Forum
Renewable Energy Questions/Discussion => Automation, Controls, Inverters, MPPT, etc => Topic started by: ChrisOlson on March 10, 2012, 05:21:54 pm
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I hope I can get this set up properly. That's why I'm asking.
I got Aux 1 set up on my solar Classic to turn on a single phase 2,000 watt water heater element powered off the inverters. I want it to come on when the bank is in float stage, then shut off when the controller drops out of float.
The purpose is to keep the panels at full power, and use the power, instead of having the controller "throttle them back" because the bank gets charged up. I set Aux 1 to come active in Float. But what happens there is that if the sun goes under a cloud the controller switches from "Float" to "Float MPPT" and it starts cycling the relay on and off real fast.
So I decided to try a different setting.
The following photos show the settings in the controller:
This is the charge voltages:
[attachimg=1]
I'm using this Aux function to activate the port:
[attachimg=2]
This is where it gets confusing. I set the trigger voltage at 30.0, which is the same as absorb voltage. I haven't set the offset yet.
[attachimg=3]
I put a delay time of 1 hour on it so the Aux 1 port doesn't become active unless the bank has been absorbing for one hour. I put a hold time on of 180 seconds, which the way I understand it, will hold the port active for 3 minutes after it drops out of this charge stage.
[attachimg=4]
What I don't understand is what I should set the offset at? The way I read the manual, it will bring the Aux 1 port active after the one hour timer expires if the voltage is above the high set point, minus the offset.
Or it's possible I'm not understanding this Aux function at all.
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Chris
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Chris
I've tried all sorts of different settings trying to utilize the solar when the bank is full but have failed it seems. I don't have time to play as much as I want with the system but what I have found is using P&O legacy and even Wind with the solar seems to allow me to do as I wish to use excess energy.
Sorry I can't help you but hopefully Ryan or Bob will chime in to give some advice.
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Well, here's another one I came up with. And this I'm pretty sure will work. It says in the manual that the Aux trigger voltages are temperature compensated. So.......
I use the Aux 1 port in Diversion Mode:
[attachimg=1]
I set the trigger voltage at 30.0 and the off voltage at Float (maybe I should drop this a couple tenths below float so it stays on in Float):
[attachimg=2]
Then I set a one hour delay so the port doesn't become active until the bank has been absorbing for one hour and it's actually starting to "throttle the panels back" at that point, so I need to add the extra 2 kW load to keep them at full power. And I added the 3 minute hold before it drops out in case the sun would go under a cloud, or a heavy starting load would cause a temporary dip in bank voltage:
[attachimg=3]
I dunno. I THINK this scheme will work to do what I want.
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Chris
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Chris, You were on the right track with "Waste Not" mode. That's the one you want I'm pretty sure.
It allows diversion to be used that follows the charge stages as well as battery temperature
compensation.
I think you are using Aux 2 for Clipper control, which for the moment is the only Aux output with PWM (around 500 Hz).
I do know that Aux 2 Waste Not mode works very well for what you are trying to do when it is used with a SSR.
OK, so Aux 1 works the same way but instead, will not switch nearly as fast.
The offset voltage is voltage offset relative to whichever charge stage the Classic is in now. EQ, Absorb or Float.
Since in normal operation, the Classic will raise the input voltage (throttle) in order to keep the battery voltage
from rising above the charge stage voltage, setting the Waste Not Offset voltage just below the charge stage
voltage set point will cause the Aux output to turn on your diversion load to instead keep the voltage regulated.
In this mode, the normal charge stage set point voltage is more of a fail safe set point. The idea is for your load
to keep the battery voltage regulated rather than the throttling of the input voltage of the Classic.
What I recommend is to bring the offset down below the wanted set point by a tenth or two of a volt and
raise the normal set point votlage a tenth or two tenths of a volt above the desired set point voltage.
That should give just a little bit of separation in voltage so the diversion load has more of a chance of doing
the work than the throttling of the Classic input voltage to keep the battery voltage constant.
For the example just below here, assume the Classic is in the Absorb stage.
On the delay and hold time, these really should be set pretty fast responding. It has nothing to do
with how long the Classic has been in the Absorb (or EQ or Float) stage itself... Just how long
after the voltage has risen above the set point till it turns on your diversion load.
The Aux1 output should turn on (HI) when the Classic sees the battery voltage rise above the
Absorb voltage setpoint -minus- the offset voltage HIGH AFTER the delay time amount.
i.e., the delay time is the amount of time that the Aux1 will take to turn on after it sees the battery
voltage rise above the Absorb voltage -minus- the small amount of Offset voltage HIGH setting.
So as soon as the battery voltage rises above the High voltage, the Aux 1 output should start the diversion so
the throttling doesn't happen and so you can use the power to heat water of whatever.
So when the Aux turns on, your battery voltage will start to fall.
Then, when the battery voltage falls below the Absorb voltage setpoint -minus- the offset
voltage LOW setting, the Aux 1 should go low again AFTER the HOLD time amount.
Then the battery voltage will rise again and the battery voltage game should repeat again.
The Aux 2 Waste Not when used with an SSR will be "smoother" than the slower (non PWM)
Aux 1 version of the same thing which makes sense.
The reason that Aux 1 doesn't use the 500 Hz PWM is because it has that relay option which would
cause a buzzing as well as giving an option for Bang-Bang external relay operation for all of the
Aux1 modes. That being said, we ARE planning on adding a 500 Hz PWM mode as well to Aux 1
as soon as I get one of them round to-its.
This mode is somewhat hard to explain so I hope I didn't mess it up too badly !
boB
PS. Ooops ! It looks like you have an extra digit and decimal point on the Delay time setting.
I better make sure I fix that ! It IS adjustable to tenths of a second though.
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Thanks boB. I think I understand it a little better.
Let's see if I got this right (this is my solar controller BTW - not the wind one):
I got the absorb voltage set at 30. So I should change that to like 30.2 and set the offset V HIGH to -0.2 so the diversion kicks in right at 30.
Now, let's say that the load is just right - the bank is holding right at 30.0 and the load is just enough to to keep the panels at full power. But a cloud passes over and the power drops. The voltage falls to 29.9. If I set the offset low to -0.2 it will allow it drop to 29.8 before the hold timer starts its countdown to shut off the diversion load.
Do I have this right?
Now - let's say the bank gets thru absorb and it's floating. The float is set at 27.5 volts. Will it do the same thing, and use the same offsets in float mode too, except now using the 27.5 for the set point?
If so, this is what I was looking for. During absorb it will heat water intermittently if there is available extra power from the panels. During float it will heat water continuously to keep the panels running at wide open throttle as long as there is enough solar power to do it.
EDIT:
Here's what I did:
I raised the absorb set point to 30.1 volts. I didn't change float because I got that set plenty high anyway. I like to float my Surrette's so they're bubbling just a tiny bit to keep the electrolyte mixed good. The Surrette's are low specific gravity batteries and they require these high voltages for proper charging or they'll die an early death:
[attachimg=1]
I set the high offset to -0.1 so the diversion comes on at 30.0 and the low at -0.5
[attachimg=2]
[attachimg=3]
I set the delay timer to the lowest it will go and the hold time to 180 seconds so the relay will only cycle a max of once every 3 minutes when the bank is in absorb and still requiring a fair amount of amps for charging:
[attachimg=4]
I hope this works. I'll find out tomorrow :)
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Chris
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Thanks boB. I think I understand it a little better.
Let's see if I got this right (this is my solar controller BTW - not the wind one):
I got the absorb voltage set at 30. So I should change that to like 30.2 and set the offset V HIGH to -0.2 so the diversion kicks in right at 30.
Now, let's say that the load is just right - the bank is holding right at 30.0 and the load is just enough to to keep the panels at full power. But a cloud passes over and the power drops. The voltage falls to 29.9. If I set the offset low to -0.2 it will allow it drop to 29.8 before the hold timer starts its countdown to shut off the diversion load.
Do I have this right?
Yes
Now - let's say the bank gets thru absorb and it's floating. The float is set at 27.5 volts. Will it do the same thing, and use the same offsets in float mode too, except now using the 27.5 for the set point?
If Float is set for 27.5, since Offset is set to -0.2, the it should turn on at about 27.3 (25.7 - 0.2)
You may want to add a tenth or two to that 27.5 as well as the Absorb and/or EQ voltage.
I think I am remembering correctly be stating that the voltage has to rise above that offset voltage
by 0.1V and not just being equal to the offset voltage but I may be off by 0.1V.
The Offset LOW should (or won't?) be set at exactly the same as Offset HIGH. I think there
has to be a tenth or two of difference at least. The closer they are together, the faster
they Aux1 ~should~ toggle I believe.
Chances are slim that the dump load will be right dead nutz on to balance things.
BTW, are you using a contactor / relay or a solid state relay for this particular load ??
Or, maybe the load is on the AC side of the inverter which can also be done.
If so, this is what I was looking for. During absorb it will heat water intermittently if there is available extra power from the panels. During float it will heat water continuously to keep the panels running at wide open throttle as long as there is enough solar power to do it.
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Chris
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Thanks boB. I think I understand it a little better.
Let's see if I got this right (this is my solar controller BTW - not the wind one):
I got the absorb voltage set at 30. So I should change that to like 30.2 and set the offset V HIGH to -0.2 so the diversion kicks in right at 30.
Now, let's say that the load is just right - the bank is holding right at 30.0 and the load is just enough to to keep the panels at full power. But a cloud passes over and the power drops. The voltage falls to 29.9. If I set the offset low to -0.2 it will allow it drop to 29.8 before the hold timer starts its countdown to shut off the diversion load.
Do I have this right?
Yes
Now - let's say the bank gets thru absorb and it's floating. The float is set at 27.5 volts. Will it do the same thing, and use the same offsets in float mode too, except now using the 27.5 for the set point?
If Float is set for 27.5, since Offset is set to -0.2, the it should turn on at about 27.3 (25.7 - 0.2)
You may want to add a tenth or two to that 27.5 as well as the Absorb and/or EQ voltage.
I think I am remembering correctly be stating that the voltage has to rise above that offset voltage
by 0.1V and not just being equal to the offset voltage.... I may be off by 0.1V.
The Offset LOW should (or won't?) be set at exactly the same as Offset HIGH. I think there
has to be a tenth or two of difference at least. The closer they are together, the faster
they Aux1 ~should~ toggle I believe.
Chances are slim that the dump load will be right dead nutz on to balance things.
BTW, are you using a contactor / relay or a solid state relay for this particular load ??
Or, maybe the load is on the AC side of the inverter which can also be done.
If so, this is what I was looking for. During absorb it will heat water intermittently if there is available extra power from the panels. During float it will heat water continuously to keep the panels running at wide open throttle as long as there is enough solar power to do it.
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Chris
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BTW, are you using a contactor / relay or a solid state relay for this particular load ??
Or, maybe the load is on the AC side of the inverter which can also be done.
On the solar controller I'm using a contactor and the load is on the AC side of the inverter. It's a 2 kW water heater element. When there is just solar and no wind the load will be too much and the relay will cycle quite a bit during absorb. When there is wind I basically don't even need the solar because the turbines put out WAAAAY more power than the solar does. So under those circumstances the solar can be used to heat water continuously all day, which keeps the MPPT turbine charging batteries instead of running Balls Out up against the clipper.
Thanks again, man. I'm pretty sure I have it close enough to work the way I want. And I can tweak it a few tenths from there to tune it. At least I now understand the setup of this Aux function. I hope this helps Watt too to figure out a way to use his.
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Chris
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Excellent ! I'll try to get some of this text (or something like it) incorporated into the manual, too.
It couldn't hurt. Thanks for presenting the question and/or opportunity to explain this further.
boB
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Thanks boB, I think I now understand a lot more about this also.
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I'm happy to say that the Waste Not Hi Aux 1 function is working beautifully.
It cycled the water heater on and off as required during absorb - it would turn it on and it would stay on for about 3-4 minutes, then it would turn off for about five. As the bank got done with absorb it was turning it on and leaving it on for up to 10-15 minutes.
When the controller dropped into float it's got the water heater on constantly now. The panels have been running at wide open throttle all day, even in float.
A guy couldn't ask for a slicker setup.
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Chris
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Thanks for bringing this up in the forum. I'll be referencing this thread very soon. Nothing like doing things the right way. ;D
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I have the two jumpers on the lower left of the Classic's board (by the ethernet connector) set for 12 volt output from the Aux 1. I run a little 12 volt ice cube relay with it, used as a pilot relay. The ice cube relay tuns on 24 volt power to the 24V coil in a 20 amp two pole fan center contactor, which in turn flips on the 240 volt power to the water heater element.
I could have jumpered the Classic's Aux 1 as a switch and eliminated the pilot relay. But when handling 240 volt power I like the extra step of isolation that the pilot relay provides from the DC control to the AC power.
My final settings after "tweaking" were to set the absorb back to 30.0, the V HIGH offset to +0.1, the V LOW offset to -0.4, the delay to 9 seconds, and the hold to 180 seconds.
The 2 kW aux load is too much for the absorb stage unless there's decent wind power coming in to provide the power to keep the load engaged. But in float stage it's about perfectly matched on a nice sunny day like it was yesterday. Yesterday I dumped 2 kW from the solar panels into the water heater for about 5-6 hours during float and it got the primary water heater (55 gallons) up to 168 degrees. All that power from the solar panels would've been "throttled back" by the controller, and never harvested, without this aux load function.
It works perfect.
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Chris
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This is how it starts...
Someone yaks about how nice a device is then it gets on your "must have" list.
Chris just did it with the Battery Monitor by Midnite. Now with the Classic.
I just can't afford it yet. :o
Tom
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Other folks have controllers that could do something like this too. But I don't think they can do it to the same level of sophistication. It appears to me that boB and Robin dumped all the features into the Classic that everybody always wanted in the MX/FX, but never made it in there for whatever reasons.
For a lot of folks those features are not necessary. But when you're trying to achieve a level of sophistication and control of your power system to where the system "takes care of itself" to a degree of reliability that approaches 100%, the extra money spent on this kind of equipment is well worthwhile. Things like HyperVOC where you can wire panels to run at 141 Voc on a 150 volt controller, and don't have to worry about blowing the caps in your controller on really cold days, is pretty darned nice.
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Chris
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Yes the Classic is on my must have list also, but wont be for a while. :-\
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I wanted to report back on using the Waste Not Hi Mode in the Classic for water heating, mainly for Watt.
I've had this set up for a few weeks now, and it works totally awesome. This is not a voltage-based "dump". The Classic is smart enough so that it will only turn on the water heater if there is excess power available from the RE system for the particular charge state it's in.
In Bulk MPPT I never see the water heater come on. But once it gets to Absorb voltage the Classic looks at what the batteries are taking for current vs what it determines is available from the panels. If there's more power available than what is being used by the bank it activates the Aux port and we start heating water. In the initial stages of Absorb when the bank is still pulling up to 80 amps it will cycle the water heater on and off to maintain the Absorb voltage. As the bank gets charged up it leaves the water heater on more. At the end of the Absorb stage the water heater is on all the time.
I have the ending amps for Absorb set at 30 amps. So when the batteries are pulling 30 amps it drops into float and finishes the last 5% of the battery charging. Once in float the water heater is always on until the stat kicks it out at 190 degrees.
The solar Classic interacts beautifully with the wind Classics. Even if there is little or no solar power, if the wind system gets the bank up to the Absorb level and holds it there for the max Absorb time set in the solar Classic, it activates the Aux1 port and starts heating water with wind power.
Both of our 55 gallon water heaters are up to 190 degrees by mid-afternoon for the whole last two weeks. We have so much hot water heated with free electricity (well, not "free", when you figure in equipment costs, but still.....) that my wife has been using her dish washer just to use it up and cool the water heaters down a bit so we don't get burned when we take a shower or something.
I have used various relay type voltage based controllers to do this, from Coleman Air ones to Morningstar RD-1's. This is the first time I have had a smart enough controller to properly charge the bank, and use the excess power to operate a water heater without using PWM schemes for "dump". The PWM schemes are fine, but it requires an SSR and driving water heater elements at part of their rated power with PWM does not provide efficient water heating. Using a simple contactor and powering the element at it's full rated 2,000 watts @ 240 volts is about 95% electrically efficient, and it works to actually get LOTS of hot water.
If we get some poor power days, our two water heaters can store enough hot water for about five days if we cut back on the excess use (like the dish washer) before the water gets too cold to take a comfortable shower. And on a good we can heat them both from well temp to 190 with this system in one day. I have figured out that it takes about 36 kWh of power to heat both of our heaters from well temp to 190.
I have to giggle with this system. When all the energy saving folks are promoting turning the thermostat down in your electric water heaters to save on power, we got ours cranked to the Max. And when we turn on the faucet we get hot water with a good head of steam on it ;D
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Chris
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Chris, thank you for the update. I am very interested in this setup of yours. I am going to lowes this evening to get an additional water heater and will start gathering the parts to ' copy ' you. :P
I will go back and read the thread to get a better understanding of what you have there before I begin the million questions to you. Anyway, thanks again.
Mike
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Well, before you start with the million questions, I'll just tell you. It's really simple.
The water heaters come with 4500 watt elements. You replace those with what fits your RE system output. I'm using 2 kilo watters. The primary heater is the one that has the hot water pipes coming out of it and going to the house. The pre-heater is the other one that has the cold water line coming into it. You can use one, or two, or three - whatever you want. We got two 55 galloners
The top element in the primary heater has a thermostatical thing with a swapping relay on it. You set that at 125° and when it gets to 125 the swapping happens and it sends the power to the bottom element. You crank the stat wide open on the bottom one. Ours goes up to 165 but it really heats up to 180-190 at Max Dawg.
You replace the bottom relay thingy with one of them swapper ones like what's on the top element. So when the bottom gets to Max Dawg it clicks and the swapping thing happens. Except the swapping thing now sends the power to the top element in the pre-heater, which is set at 125. When the top in the pre-heater gets to 125 the swapping thing happens for the last time and it sends the power to the bottom element, which is set at Max Dawg.
When the bottom element in the preheater reaches Max Dawg you're all done heating water.
The Aux 1 port on the Classic outputs 200 mA 12 volt DC. You run a little ice cube relay with that, using the ice cube relay as a pilot to turn on a contactor with a 24 volt (or whatever voltage system you got) coil. The contactor turns on the power to the water heaters.
And finally you put a manual switch in to engage your contactor to heat water in the event your RE system don't make enough power and you have to emergency heat some with the genset.
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Chris
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Chris;
I just love it when you talk dirty like that! ;D :o
Tom
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The Aux 1 port on the Classic outputs 200 mA 12 volt DC. You run a little ice cube relay with that, using the ice cube relay as a pilot to turn on a contactor with a 24 volt (or whatever voltage system you got) coil. The contactor turns on the power to the water heaters.
This is photo of my water heater relay box. I actually got contactors in there and I got a switch for ON, OFF and AUTO:
[attachimg=1]
[attachimg=2]
The top right contactor is a 25 amp Honeywell with a 24 volt coil in it. That's the one that the Classic runs with the ice cube relay. The Allen-Bradley three poler has a 120 volt coil and that one is the one that closes when I flip the switch to ON.
You only have to switch one leg of the split phase because that's all them swapper relays do in the water heaters, and there's only three wires going to these 240 volt domestic water heaters. One leg is hot all the time and they switch the other leg to swap from element to element. The neutral, which isn't really neutral in the water heater, is used for ground.
You only need one relay. I got two in there just because when I flip my big transfer switch to take my inverters and battery bank offline and power stuff just with the genset, I got no 24 volt power available to run the coil in that 25 amp Honeywell. But the Allen-Bradley one still works.
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Chris
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I just love it when you talk dirty like that! ;D :o
Yeah. Them water heaters are tricky business. Before I figured out a way to use all them thermostatical things in there on two heaters, we popped the steam valve on the primary heater twice in one week. My wife was not impressed.
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Chris