Hello
i have been trying to read on how to use aux to hook up a water heater and use excess PV power to heat water instead of wasting it during absorb and float stages of charge.
after reading and reading i think i understand the concept of hooking up the water heater:
I understand that i can hook up Aux 1 to a SSR and set the diversion settings in the aux 1 control and tell the SSR when to turn on and off depending on my specific voltage settings.
i think that SSR i need to use depends on the heating element i want to use. (this is where i get confused and am not sure to determine how to size/pick the correct heating elements. im not exactly understanding the ohms thing involved)
am i getting those correct?
i however cannot understand how i can regulate the excess power while in absorb mode.
for example;
my system has enough power to complete a full absorb cycle. At the start of the absorb cycle the required power is 30.5V @ 31A = 950 watts. my system can produce 1.5kw in peak sun so i have about 550 watts of excess power when the absorb stage starts (obviously more as absorb goes farther along). problem is once the clouds come out i drop below the 950 watts and come out of absorb. i cannot understand how this would work with the SSR. will the heating element only pull the "extra" power that the absorb stage is not using or will it start trying to pull power off the battery bank also dropping the voltage? and if so wouldn't that just keep taking me out of absorb and not letting me complete a full charge cycle?
thanks
Another dummy wants to know :)
There are some settings in AUX called Waste Not that may be what you are looking for - you may want to search the forum for WATER HEATING and also using SSR with AUX and search for Waste Not too.
Lots of past discussions on these topics that will give you some detailed information.
Larry
ksman, sigp,
We've been preheating water with "opportunity load" with our Classic and a 3.2 kW PV array for several years now. It works very well in the summer period especially for us. We're using a 40 gal Marathon tank, with 1,200w 48VDC elements. We replaced the stock elements with DC elements and pulse those elements via SS relays. My preference is to use Aux2, if available, and use the Waste Not Hi feature as Larry suggests (aka 'use-it-or-lose-it, you might google that too). This lets you program settings relative to your normal charge settings, allowing the typical 3-stage charging to be maintained.
Some cautions - the stock thermal/discs won't break the higher DC current, so don't try that. You'll want 24V elements if that is your bank voltage. DC breakers need to be sized for the wire & elements, and solid state relays need to have heat-sinks or they will not last.
One suggestion you might also consider is to raise the temp settings on the tank. The allowable upper limit temp for this tank is 170F. If you put a mixing/tempering valve on the outlet it allows you to effectively store more BTUs when available. This goes against conventional thinking - to avoid mixing cold, and unnecessary heat losses we normally set lower ~120F) - but with PV/diversion the energy source is free, and otherwise untapped. Ours goes to a LPG instantaneous water heater and we set the outlet temp from the Marathon to meet the max inlet to the LPG unit.
Here is a couple of albeit dated links, but offer some good descriptions of the goal & logic:
http://www.fieldlines.com/index.php/topic,130053.html (http://www.fieldlines.com/index.php/topic,130053.html)
http://outbackpower.com/forum/viewtopic.php?f=29&t=2865&hilit=electron&start=25 (http://outbackpower.com/forum/viewtopic.php?f=29&t=2865&hilit=electron&start=25)
There are other ways. This is only one. Good luck, ks
thank you again for all the replies.
So i have been reading more and my next question would be:
Why choose Aux 2 (waste not PWM) vs Aux 1 (diversion)?
I have whizbang Jr on Aux 2 and dont want to have to remove it.
i seen another post where they switched from using aux 1 diversion to aux 2 PWM so that they could utilize full PV power even when in absorb mode but i cannot understand why they did this and why it cannot be done with aux 1 and diversion.
i would like the dump load (water heating elements) to always be able to use the excess power when available even when in absorb mode, but i dont want it to take away power and limit the absorb charge (only want it to go on when there is excess power and not take anything from the batteries).
any explanation on why using aux 2 waste not is better than aux 1 for this kind of application
Aux1 will work. The main difference is that Aux1 is a relay action (on- or off), whereas Aux2 uses pulse width modulation (PWM), so it can pulse much faster (hundredths of times per second I believe). There's a pretty good explanation in the Classic manual, in part:
Aux 1 diversion mode is similar to Aux 2 diversion mode except that it does not PWM, Pulse or buzz at
hundreds of Hz rate. Instead, Aux 1 diversion goes Active at or above the "High" voltage setting, after a
programmable "Delay" time, and goes Inactive when the voltage drops below the "Low" voltage setting
after a programmable "Hold" time. These Delay (or Attack) and Hold times are adjustable in 0.1 Volt
increments.
Our experience has been that Aux2 is more responsive and yields a bit higher "harvest" of available energy. With Waste Not, it is working relative to your charge settings and only burns off what's available above the battery needs.
~ks
Here's a bit more up to date discussion on some of our experiences with both Aux1 & Aux2. I'm sorry I couldn't recall where this was posted yesterday. Maybe something of use:
http://www.fieldlines.com/index.php/topic,148575.msg1032997.html#msg1032997 (http://www.fieldlines.com/index.php/topic,148575.msg1032997.html#msg1032997)
thank you for the reply kitestrings.
now i can understand the difference between using aux 1 and aux 2.
next question would be abut using AC heating elements vs DC heating elements. I understand that when using the AUX 2 PWM a DC element is preferred because of the rapid on/off state of the element. Is there any way i can use aux 2 PWM with AC?
only reason for asking is my how water tank is about 40-50 feet away from my battery bank and i dont want to have to run large wiring if i don't need to.
another question is if you were to use aux 1 diversion is there any way to get it to go into divert only after float has been reached? reading the ouback forum it seems the newer outback controllers have this option. only reason is my folt voltage is 26.7V and absorb is 30.5 so if i set the diversion voltage to the float voltage it will start diversion before reaching the absorb stage.
if i cannot get the PWM aux 2 route to work i would like to know if there is a possibility to divert in float mode only?
thanks again. really helpful info.
after i gather all info needed i will try to do a step by step so others can know exactly how to accomplish this.
In my mind the biggest reason for using DC is that with AC your tying up more capacity from your inverter, and adding losses which may be be of lesser concern. I'm old school but prefer not to put loads thru the inverter that can be served directly.
I'll defer to others on the float trigger. It may be something that's been added, I just don't know.
Lastly, a guy named "Crewser" wrote a similar white paper if you look for it in the OB thread above. We started this on an OB MX60 and transitioned over to the (superior;>) Classic.
~ks
If you wait until it goes to float you could be missing out on a lot of available power - since it takes a long time to get to float and the current cuts down so much.
Most people don't use AUX 2 because they have a Whizbang on their system. It will give you a much better understanding of your battery health and also control. If you have the Whizbang there are AUX settings that let you turn on a load at for example 90% SOC and off at another SOC. If you have Whizbang you can set up ending amps to terminate your absorb instead of using time.
What kind of batteries do you have ? I have lead acid 24v system and 30v is my equalize voltage . Why do you have your absorb voltage set at that ?
Larry
thanks again guys.
I don't mind running AUX 2 PWM with AC off my inverter as long as its ok for the inverter going on/off like that to satisfy the PWM pulses. (i thought that was the main reason for going DC?)
I am running a set of Interstate GC2 batteries from costco setup for 24V 416AH checked everywhere online and even called interstate to verify the charge voltages. i am currently using the WBjr to end absorb at 8amps as specified by the manufacturer.
can i run a SSR (AC/DC W/PWM) and WBjr off aux 2 at the same time?
will the PWM SSR Aux 2 route work with 2 CC in Follow Me? i know kitestrings has a 2 CC setup but from what i can understand from reading the other forum posts the issues are from the wind part of the setup.
if i have 2 CC with 2 seperate PV arrays doing follow me (to my 24V battery bank) will this AUX 2 PWM SSR "waste not" mode (so you can allow excess dump while in absorb and float mode) work and dump the excess from both seperate arrays?
Quote from: ClassicCrazy on October 27, 2016, 06:24:03 PM
If you wait until it goes to float you could be missing out on a lot of available power - since it takes a long time to get to float and the current cuts down so much. just wanted to know if that was an option. ideally i want to setup AUX 2 PWM "waste not" with SSR so i can start using excess power during the absorb stage and not take away from battery charging
Most people don't use AUX 2 because they have a Whizbang on their system. It will give you a much better understanding of your battery health and also control. If you have the Whizbang there are AUX settings that let you turn on a load at for example 90% SOC and off at another SOC. If you have Whizbang you can set up ending amps to terminate your absorb instead of using time. if i dont use AUX 2 with the above stated setup how will it just use the Excess power while in absorb mode?or is that not possible with this route
Larry
thanks for the input
You can only use Aux2 for Whizbang or for controlling - not both at the same time.
I looked up your batteries and the manufacturer does say to have those voltages that high . That is much higher than most other battery manufacturers have for their batteries. Interesting .
http://www.batteries-faq.com/activekb/questions.php?questionid=1
Larry
A question: In a multiple Classic system on the same battery bank, is it not possible to use the Follow Me and use the Aux2 in the slave to run the opportunity load?
yes my thoughts exactly.
is it possible to use AUX 2 "waste not HI/opportunity load" on the slave CC in a follow me setup on the same battery bank? will the opportunity load be taken from both the different arrays that the CC's are hooked up to or will it only get opportunity load from the CC that aux 2 is being used?
I would bet on the Slaves power being used to supply the '' WN Hi'' demand.
That being correct, the array that has the higher output latest in the day should be the one to tap... Do you agree?
too bad only would be taking power from 1 array.
here's another question about the heating element.
if you have a AC 240V 4800 watt heating element can you just hook that to your 120V inverter and still work? i know it will not use the entire 4800 watts but just want to know if that is possible or do you need a 240V capable inverter for that to work?
just trying to determine the best route for choosing to power the heating element AC vs DC. i like AC just because i can use the stock thermostat/wiring that came with the heater, only problem is the heater is AC 240V and my inverter is only 120V capable. i'm assuming this is possible as if you can run it off other lower voltage power sources i dont see why not 120V also.
in this thread it seems they are running AC power using AUX 2 Waste Not HI PWM and it seems the inverter is fine with the SSR pulsing on/off not letting the element pull full power but only the excess power that the panels are providing. can anyone confirm this is OK?
http://www.fieldlines.com/index.php/topic,147132.0.html
can i assume for a 240VAC 4500 watt heating element powered by 120VAC source
240V/4500W = 18.75A
240V/18.75A = 12.8 ohms
120V/12.8 ohms = 9.37A
120V x 9.37A = 1125 watts
so can someone confirm i can use my 120V inverter with this 240V heating element and the heating element will have a max draw of 1125 watts!
sorry 2 questions 1 post
I do AC diversion using an SSR. I found with the Magnum inverters I have that the Classic PWM frequency was so fast that the Magnums could not keep up and my lighting etc flickered like a discoteque (sp?). I ended up dedicating an inverter to only diversion and battery charging but then ran into other issues that caused me to search for a different method. Bob has posted that the Midnite PWM frequency can be dropped in a wind mode of some kind but I had already built my own diversion control when I learned that.
The power used by heating elements is dependant on ( among other things) the voltage. If you half the voltage you will use 1/4 the power. So that means 4000 watt 240 V elements will use 1000W at 120 V. This is one of the problems with diverting power - the heating elements must match the voltage supplied reasonably closely. You can source 120V elements and could put a lower element with a suitable wattage rating in your tank. Install a 120V thermostat to control this element. Leave your upper as a 240. Set the temperature on the 120 higher than the 240. When diverting using the 12O the HW will rize to top of the tank and "push" your 240 element off. I have a large collection of heating elements now. I found what worked for me when using the Midnite AUX 1 system waste not Hi was an element that was about 1/2 or less of my array STC rating.
Will
More - If you are using AC diversion from your inverter then you will be using the excess power from both arrays as both Classics are wired into common + & - buses on the output side. These buses supplies both your batteries and the inverter. So the diversion controlled by one Classic will effectively divert the excess power from both arrays.
Will
Today there is a guy out here doing a workshop on connecting series solar panels directly to an ordinary AC water heater so you don't need any inverter or batteries, etc. You would only need an SSR to turn off DC power to lower heating element if water gets too hot . He keeps upper heating element connected to AC . Makes sense in a lot of ways for heating water - I know it is a bit off topic to this diversion subject. Though maybe it makes more sense to take a string of panels off the batteries in the summer when there is extra power and send it directly to hot water heater using this method.
Larry
Larry, like Joe Friday (Dragnet) said.... Facts, mam, we just need the facts.... Let us know a link or two if you get them...
that array 'diversion'' in summer would be simple. Just need a lock out switch setup to keep the 2 DC/Ac separate
Quote from: WillEert on October 29, 2016, 11:13:25 AM
I do AC diversion using an SSR. I found with the Magnum inverters I have that the Classic PWM frequency was so fast that the Magnums could not keep up and my lighting etc flickered like a discoteque (sp?). I ended up dedicating an inverter to only diversion and battery charging but then ran into other issues that caused me to search for a different method. Bob has posted that the Midnite PWM frequency can be dropped in a wind mode of some kind but I had already built my own diversion control when I learned that.
The power used by heating elements is dependant on ( among other things) the voltage. If you half the voltage you will use 1/4 the power. So that means 4000 watt 240 V elements will use 1000W at 120 V. This is one of the problems with diverting power - the heating elements must match the voltage supplied reasonably closely. You can source 120V elements and could put a lower element with a suitable wattage rating in your tank. Install a 120V thermostat to control this element. Leave your upper as a 240. Set the temperature on the 120 higher than the 240. When diverting using the 12O the HW will rize to top of the tank and "push" your 240 element off. I have a large collection of heating elements now. I found what worked for me when using the Midnite AUX 1 system waste not Hi was an element that was about 1/2 or less of my array STC rating.
Will
thanks for the reply.
i am using a cheap samlex 2000W inverter so i hope that it can handle the SSR pulse guess i will have to just try and find out myself.
what method did you end up going with since the AC inverter route was giving you problems?
I understand that i will not get the Full 4500W out of the 240V heating element if i only put 120V to it, but my question is, is it possible to connect my 120V inverter to this 240V heating element? i actually only need about 1000W of diversion power anyway.
would i need to change the thermostats/wiring to make it happen or can i just plug and play with the black and red wire? i was planning to only hook up the bottom heating element.
thanks again for any help
I would NOT PWM an SSR on either the A.C. or the D.C. side of an inverter as it would likely not work as expected and may well release the magic smoke they put into the equipment at the factory. It can be expensive getting it all back in after a catastrophic release of said smoke.
Tom
You've just reinforced for me why DC makes more sense. It's worked well for us since ~2007. If you only need 1,000 watts then your only talking 40A when it is fully engaged. Much of the time it will be something less than that. They are readily available in the 900-1200 w range IIRC. With DC elements you're not affecting the inverter at all, and you can use excess power from both of your arrays - well, assuming they are both tied to the one bank - you really are just taking would be lost energy once the bank is satisfied. I can imagine buzzing LED lights, and potential noise on audio & electronics with AC, not to mention what toll it might take on the inverter long-term.
For us, on a sunny weekday when the kids are off to school and my wife and I are working, the batteries might be well into absorb cycle by late morning. If they're calling for only ~500 watts, there is another 2.5 kW available for diversion. There's something to be said for the KIS approach IMO.
The direct array approach sounds promising, and should be interesting to follow, but in my mind it's more of an alternative approach, say like considering a solar (thermal) water heating system. Here you already have the investment in panels based on the electrical needs, and you're just looking to leverage more of the available energy.
~ks
Quote from: Westbranch on October 29, 2016, 02:02:09 PM
Larry, like Joe Friday (Dragnet) said.... Facts, mam, we just need the facts.... Let us know a link or two if you get them...
that array 'diversion'' in summer would be simple. Just need a lock out switch setup to keep the 2 DC/Ac separate
Attached is an article Pete wrote about direct PV to AC hot water heater element - he may have more up to date info - email him - his address is at end of paper.
He had a paper today with equivalent ohm ratings of various AC hot water heating elements. I was not able to stay for his whole talk.
Larry
Quote from: kitestrings on October 29, 2016, 07:47:35 PM
The direct array approach sounds promising, and should be interesting to follow, but in my mind it's more of an alternative approach, say like considering a solar (thermal) water heating system. Here you already have the investment in panels based on the electrical needs, and you're just looking to leverage more of the available energy.
~ks
True what you say about if you already have PV electric system in.
One of the presenters at the talk didn't have any PV and wanted to see if it was less to install PV direct to water heater than to install solar thermal system. He showed all the numbers he crunched and PV was less and do it yourself easier. The big benefits for him were just being able to run a wire in to the house instead of insulated pipes full of glycol , pumps, etc.
So he ended up buying a kilowatt of panels and making his own rack in the back yard to put them on. He had some data he collected from past summer. So without the cost of batteries or inverter it does seem to make sense for water heating.
Larry
I run my AC PWM diversion system at 10 hz and the MS4448 PAE inverter just happily hums along as the load changes. It did not like the fast frequency of the Midnite PWM at all - it seemed very unhappy. I think the magic smoke would have leaked out quite quickly at the high PWM frequency. The inverter could fail tomorrow I guess but so far it seems ok after 14 months or so. I vent the heat generated from the efficiency loss into my garage and do not worry too much about efficiency. I run two 2kw 240V elements in my tank using simultaneous control - first the lower element PWMs up to full load and then the upper one turns on and takes any additional power available. Fun. The standard thermostat gave me problems as it did not turn on quickly enough after it opened. This meant that the tank would have to cool down about 15F before I could divert again. So I configured an electronic thermostat which I run at 5F differential. The thermosdisc thermostats I turn the set point up above the electronic one as backup in case my system decides to try to run amok. If the electronic thermostat stops diversion by the next day the tank has cooled down the 5F and the diversion starts as soon as power is available.
Will
Quote from: ClassicCrazy on October 29, 2016, 08:28:37 PM
He had a paper today with equivalent ohm ratings of various AC hot water heating elements. I was not able to stay for his whole talk.
Thankfully the ohm value of an element is easy to calculate, just divide the wattage rating by voltage to get current draw, so a 120v 2Kw element is 2000/120 or 16.66 amps, the ohm value is then 120/16.66 or 7.2ohms
A problem with using a 120 vac rated element with lower voltage DC is that the power of the element is significantly reduced. So the 2Kw element connected to a 48v battery would take 48/7.2 or 9.26 amps of current from the battery
Power output would then be 48*9.26 or 445 watts.
That would take a long time to heat a 200 litre tank.
Hence the need for a 48v rated element, although these tend to be rated 300 to 600watts and be expensive.
OTOH if a higher DC voltage direct from PV array can rerouted to the element then lower cost AV rated elements can be used and respectable watts power used to heat water.
In my home system I use 90volt mpv PV strings (either 5 by 18v 140W or 3 by 250W 30v PVs).
To keep things simple when float is reached two 750w PV strings are diverted to the element using AUX1 float high to enable an SSR that connects the element to the PVs outputs. A diode commoned 3phase rectifier between the SSR and Classic prevents the Classic trying to feed power to the element.
dgd
DGD, how or why does a 3 phase rectifier work on a single phase setup?
Quote from: TomW on October 29, 2016, 05:11:07 PM
I would NOT PWM an SSR on either the A.C. or the D.C. side of an inverter as it would likely not work as expected and may well release the magic smoke they put into the equipment at the factory.
Tom
sorry tom i dont understand exactly what you are referring to. are you recommending not running a SSR with either AC or DC power? i though the only way for AC is through the inverter and only way for DC was directly from the battery bank?
what exactly do you mean by "A.C. or the D.C. side of the inverter"?
Quote from: dgd on October 30, 2016, 05:43:37 PM
Quote from: ClassicCrazy on October 29, 2016, 08:28:37 PM
He had a paper today with equivalent ohm ratings of various AC hot water heating elements. I was not able to stay for his whole talk.
OTOH if a higher DC voltage direct from PV array can rerouted to the element then lower cost AV rated elements can be used and respectable watts power used to heat water.
In my home system I use 90volt mpv PV strings (either 5 by 18v 140W or 3 by 250W 30v PVs).
To keep things simple when float is reached two 750w PV strings are diverted to the element using AUX1 float high to enable an SSR that connects the element to the PVs outputs. A diode commoned 3phase rectifier between the SSR and Classic prevents the Classic trying to feed power to the element.
dgd
dgd - Could you elaborate on that wiring from two of your PV strings to the water heater element ?
Is it like this
PV strings to rectifier to SSR to water heater element ?
You tie all the input on 3 phase rectifier together and use it only on the positive wire ?
Could you sketch up a schematic for this ?
Thanks
Larry
QuoteHe showed all the numbers he crunched and PV was less and do it yourself easier. The big benefits for him were just being able to run a wire in to the house instead of insulated pipes full of glycol , pumps, etc...
So without the cost of batteries or inverter it does seem to make sense for water heating.
Larry, I expected it would only be a matter of time before this started to make sense. The price of the panels has really dropped a lot over the past few years, and as you say it is a much simpler install. The cost and dead weight (and they are) is still the batteries in a system, so if you can avoid having to add more batteries as in this application, I can see where that would have appeal. Hope to read this soon. Thanks for sharing this article.
Quote from: ClassicCrazy on October 30, 2016, 08:24:32 PM
Quote from: dgd on October 30, 2016, 05:43:37 PM
Quote from: ClassicCrazy on October 29, 2016, 08:28:37 PM
He had a paper today with equivalent ohm ratings of various AC hot water heating elements. I was not able to stay for his whole talk.
OTOH if a higher DC voltage direct from PV array can rerouted to the element then lower cost AV rated elements can be used and respectable watts power used to heat water.
In my home system I use 90volt mpv PV strings (either 5 by 18v 140W or 3 by 250W 30v PVs).
To keep things simple when float is reached two 750w PV strings are diverted to the element using AUX1 float high to enable an SSR that connects the element to the PVs outputs. A diode commoned 3phase rectifier between the SSR and Classic prevents the Classic trying to feed power to the element.
dgd
dgd - Could you elaborate on that wiring from two of your PV strings to the water heater element ?
Is it like this
PV strings to rectifier to SSR to water heater element ?
You tie all the input on 3 phase rectifier together and use it only on the positive wire ?
Could you sketch up a schematic for this ?
Thanks
Larry
yes please elaborate on this if possible.
this link shows solar panels running direct to water heater element, but no 3 phase rectifier in the schematic.
http://waterheatertimer.org/Convert-AC-water-heater-to-DC-water-heater.html
Quote from: kitestrings on October 29, 2016, 07:47:35 PM
You've just reinforced for me why DC makes more sense. It's worked well for us since ~2007. If you only need 1,000 watts then your only talking 40A when it is fully engaged. Much of the time it will be something less than that. They are readily available in the 900-1200 w range IIRC. With DC elements you're not affecting the inverter at all, and you can use excess power from both of your arrays - well, assuming they are both tied to the one bank - you really are just taking would be lost energy once the bank is satisfied. I can imagine buzzing LED lights, and potential noise on audio & electronics with AC, not to mention what toll it might take on the inverter long-term.
For us, on a sunny weekday when the kids are off to school and my wife and I are working, the batteries might be well into absorb cycle by late morning. If they're calling for only ~500 watts, there is another 2.5 kW available for diversion. There's something to be said for the KIS approach IMO.
The direct array approach sounds promising, and should be interesting to follow, but in my mind it's more of an alternative approach, say like considering a solar (thermal) water heating system. Here you already have the investment in panels based on the electrical needs, and you're just looking to leverage more of the available energy.
~ks
thanks for the input KS. are you running the DC off your batteries with AUX 2 PWM connected to SSR for dumping during absorb and float, or are you just setup for voltage connect and disconnect?
can you specify how you have your system setup?
does AUX 1 have the same PWM and wast not HI as AUX 2?
Quoteare you running the DC off your batteries with AUX 2 PWM connected to SSR for dumping
Yes, that's right. We're using Waste-Not Hi on Aux2 on one of our two Classic's. Aux1 does not PWM. It is just a relay action.
Minor correction, but diversion, which is what we're collectively trying to do with hot water, is not really dumping. Not to split hairs, but folks sometimes consider them to be the same. Dump loading is usually a method of charge control, very often used in wind applications, but also solar with certain types of controllers. Here we are letting the Classic do it's normal three-stage charging, but setting a voltage hysteresis relative to the set-points where we can divert energy when available.
~ks
Quote from: kauaisolarman on October 30, 2016, 06:56:34 PM
sorry tom i dont understand exactly what you are referring to. are you recommending not running a SSR with either AC or DC power? i though the only way for AC is through the inverter and only way for DC was directly from the battery bank?
what exactly do you mean by "A.C. or the D.C. side of the inverter"?
Just saying that pulse width modulating the DC into an inverter is not going to work like you might think. Same with the AC out. An inverter is much different than a heating element in how it works.
This does not apply to a simple on / off switching of an SSR or mechanical relay.
Maybe you should research a bit into how a PWM and SSR work.
It may not matter but I just would not do either. I can't even imagine what pulsing an AC source with an SSR would actually do.
I just have to comment when I see statements that don't seem to make sense.
Its your gear so best of luck with it.
Tom
Tom,
I agree that there may be some unintended consequences of switching AC elements out of an inverter. I'm not sure that I agree that we're switching DC "into an inverter", but maybe I missed the reference. At least in our case, we're switching/pulsing the heating (DC) elements in our water pre-heat tank. This is no different than PWM on the bank, or circuits in any number of applications, such as PWM lighting, charging, dumping/clipping for wind...I don't see where it involves the inverter.
~ks
I have located the SSR between the inverter AC output and the HWT element. All the instrumentation shows is the amps to the tank element gradually changing as the SSR pulse on / off width alters. The voltage remains constant. I am just a learner but it seems OK to me.
Will
Will,
It sounds like you've work thru the obstacles, but I guess every approach has some. With your set-up you have were not able to use the MS PWM. I'm not sure as you mentioned what you went to - was it something homemade, or another diversion controller? You also used a dedicated inverter and custom, electronic thermostats. Sounds like no small challenge.
We originally kept the stock, inter-locked control sequence of the original tank, but eventually switch it to where both elements are pulsed (as I think you've done) so when more power is available it can be used.
as to my experience with pwm- ing after the inverter:
my solar controller is speed controlling a 100w pump for the solar hot water circulation between tank and the collector. this regulates between 100% and 30%, which probably alludes to the speed. on the lower sides of the percentage it will definitively flicker an incandescent lightbulb hooked to the inverter. but does not seem to create problems for the computer, monitors, etc.
the inverter is a small 2000w victron inverter. and i agree, it is probably not a good thing to do it. having said that the inverter has been running it for the last two years or so. i do not know the frequency of the pwm of the solar controller.
Quote from: Westbranch on October 30, 2016, 06:54:09 PM
DGD, how or why does a 3 phase rectifier work on a single phase setup?
The 3 phase bridge rectifier is used to prevent current flowing out of the Classic into the element.
The 3 AC inputs are commoned together and the PVs +ve output connected to them.
The rectifier's DC +ve output goes to Classic PV+input
This means three power diodes are used to protect the Classic's +ve pv input.
Usually the rectifier's body has a bolt hole, making it easy to mount in a box or on heatsink if necessary.
dgd
again thanks for the input everyone.
next question.
i have my absorb stage set to end with ending amps from the WBjr shunt connected to aux 2. but, I want to use aux 2 to run a pwm so i can connect the SSR and have "opportunity" load available to be during absorb stage.
should i disconnect the WBjr and just run a timed absorb stage and use AUX 2 with SSR and "waste not HI" to allow for harvesting of opportunity load,
or,
should i leave aux 2 with WBjr so my battery bank can end absorbtion stage on a set amps and run a seperate PWM controller (morningstar tristar ts-60) off the battery bank to control the SSR for my needs? IS THIS EVEN POSSIBLE?
will both these options provide the same results and allow me to start harvesting opportunity load during the absorb stages?
of course assuming we are using water heating elements to use the load
thanks again
Hi Kitestrings,
I started a topic in the Arduino section of the forum in order to build my own controller. Dgd and Paul Alting were very helpful to me as I learned Arduino C coding and put the hardware togeather. I do not want to highjack this topic but you can read about my learning and progress in the topic in that section of the forum.
Will
again thanks for the input everyone.
next question.
i have my absorb stage set to end with ending amps from the WBjr shunt connected to aux 2. but, I want to use aux 2 to run a pwm so i can connect the SSR and have "opportunity" load available to be during absorb stage.
should i disconnect the WBjr and just run a timed absorb stage and use AUX 2 with SSR and "waste not HI" to allow for harvesting of opportunity load,
or,
should i leave aux 2 with WBjr so my battery bank can end absorbtion stage on a set amps and run a seperate PWM controller (morningstar tristar ts-60) off the battery bank to control the SSR for my needs? IS THIS EVEN POSSIBLE?
will both these options provide the same results and allow me to start harvesting opportunity load during the absorb stages?
of course assuming we are using water heating elements to use the load
thanks again
Did you ever find out if you can use Whizbang on one Classic and use the AUX 2 from the other Classic - assuming you are going to be using two Classics in Follow Me mode ?
If it was me I would use ending amps with the Whizbang to make sure my batteries were full so any power diversion didn't affect that.
Larry
no still trying to figure all that good stuff out.
its hard for me because i am setting up more than 1 system so 1 system will most likely have 2 controllers in follow me and the other is a single controller.
just want to find out exactly how to harvest that "wasted power" which both systems will have. thats why the multitude of questions.
really want both systems (single and dual CC) to be able to harvest wasted power and use WBjr as it seems to be the best route for best battery charge, but i am torn as i understand WBjr can only be on AUX 2 which i need for PWM use to control the SSR for harvesting that wasted power during absorb and float mode.
exact how do i set the start and end parameters using a SSR on AUX 1 and WBjr on Aux 2? I read that with WBjr (on AUX 2) you can setup AUX 1 SSR to turn on when a certain SOC% is reached and turn off when another lower SOC% is reached all based on the more accurate SOC% that WBjr gives you. Just can't find anywhere that tells you how to set this up. can anyone help or point me in the right direction to make this happen?
this seems to be another viable option for harvesting wasted power vs the PWM aux 2 method
Quote from: kauaisolarman on November 03, 2016, 02:28:05 AM
no still trying to figure all that good stuff out.
its hard for me because i am setting up more than 1 system so 1 system will most likely have 2 controllers in follow me and the other is a single controller.
just want to find out exactly how to harvest that "wasted power" which both systems will have. thats why the multitude of questions.
really want both systems (single and dual CC) to be able to harvest wasted power and use WBjr as it seems to be the best route for best battery charge, but i am torn as i understand WBjr can only be on AUX 2 which i need for PWM use to control the SSR for harvesting that wasted power during absorb and float mode.
exact how do i set the start and end parameters using a SSR on AUX 1 and WBjr on Aux 2? I read that with WBjr (on AUX 2) you can setup AUX 1 SSR to turn on when a certain SOC% is reached and turn off when another lower SOC% is reached all based on the more accurate SOC% that WBjr gives you. Just can't find anywhere that tells you how to set this up. can anyone help or point me in the right direction to make this happen?
this seems to be another viable option for harvesting wasted power vs the PWM aux 2 method
You'd better use Aux1 waste not rather than SOC% for this WH, about the same as waste not aux2 but without pwm, just like an On/Off switch on absorb/float only.
A+
Erik
I use aux 1 to turn a 24 volt relay on using waste not hi. The relay is also controlled by the thermostat on the cylinder. The relay turns on an 80 amp SSR which supplies a 24 volt 900 watt element directly from the batteries. The element draws about 35 amps I think from memory. 900/24=37.5A.
It works very well.
Quote from: ClassicCrazy on October 30, 2016, 08:24:32 PM
dgd - Could you elaborate on that wiring from two of your PV strings to the water heater element ?
Is it like this
PV strings to rectifier to SSR to water heater element ?
You tie all the input on 3 phase rectifier together and use it only on the positive wire ?
Could you sketch up a schematic for this ?
Almost right.
The PV strings connect to the commoned AC input side of the rectifier, the pos rectifier goes to pos Pv input in Classic.
Also connected to commoned AC input is the input to SSR, the ouput goes to the element.
The controls on the SSR go to AUX1 in Classic via a small on/off toggle switch and a 70degC temperature switch on HWC.
There is also a 10,000uF 200V cap on same commoned connector.
All of this and heatsinks for SSR and rectifier are mounted in an MNDV Ali box.
There are also an ac756 DC current sensor, ltc12000 dc voltmeter sensor in there that connect to a web monitor.
I will get a nice looking circuit diagram together soon.
dgd
do the classic-SL's have the same functions in aux 1/2 as the regular classics?
when i try to scroll through the different options that aux 1 has all that comes up is on/off/diversion i do not have the option for anything else on aux 1. (there is currently nothing connected to the aux 1 terminals so i don't know if that has anything to do with it).
i want to try the aux 1 route and keep WBjr in operation. what other options are there for aux 1 and taking advantages of diversion load other than diversion/waste not?
I don't know anything about that Classic SL model except for what I just looked up on the Midnite site.
So it has no ethernet connector - no way to use the Local Status App or other monitoring software ?
I use the Local Status App for setting everything up - and when I go into Config menu there are 16 options for AUX 1 .
I just tried it on the MNGP and found out I have to go to AUX 1 then there is a Setup button you need to push to see all the options.
Larry
ok so i installed the SSR today with the AC heating element taking power from my inverter.
Aux 1 does seems to have all the same options as the regular classics.
so i hooked the SSR to AUX 1 and tried waste not HI (was in float already battery 100%) but i am sot sure how to set it up as the SSR never turned on this way.
next thing i did was set it to turn on with Float HI and that worked. it turned on the ssr and power flowed to the heating element. when the voltage dropped below the float voltage the SSR would turn off and the CC would go into float MPPT to try to bring the voltage back up and battery back into float.
this was great but i still need to wait for float stage and wasting all the power during absorb.
can someone please tell me the best option for Aux 1 when using SSR diversion while in absorb stage? if it is waste not HI how do i program it? for example my absorb voltage is 30.6V and float is 26.7V what is the best way to choose the voltages for waste not HI?
There are four other setpoints in Waste Not High - what did you set those for ?
Larry
thanks for the reply I just figured out how the aux 1 works.
1st voltage is set to when you want the SSR to turn off relative to the charge voltages (absorb/float) you set in the controller. so if your absorb voltage is set at 30.6 and want the SSR to turn off when the voltage drops to 28.6 you set the low voltage parameter to -2.0.
2nd voltage is set to when you want the SSR to turn on. it is also relative to the charge voltages you set in the controller. so if your absorb voltage is 30.6 and you want the SSR to turn on at 30.5 V you set the high voltage to -0.1.
the delay time is how long you want it to wait after it hits the high voltage setting berfoe turning on the SSR. the hold time is how long you want it to wait to turn off after it hits the low voltage setting.
this does not work fast enough and seems to keep me jumping in an out of absorb mode as my heating element can pull 1125 watts and there is only 200 excess watts when the absorb stage starts, so aux 1 turns on the element when the absorb stage starts and the element tries to pull 1000 watts and starts to drain the battery taking me out of absorb mode and not allowing a full charge cycle to be completed.
i am going to try the AUX 2 PWM waste not HI method but i am not sure how/what to set the parameters at.
it asks for "volts" and "width"
what should i set in these parameters and what to they mean?
sorry for the dumb questions but i know it will help another dummy like me in the future.
Say you start with an off-set of -0.5V, and a width of 1V. If the absorb is say 29.6V, the PWM will start to become active (pulsing) at 29.1V, and become fully active - no longer pulsing, full on - at (29.1 + 1.0 =) 30.1V.
It will take a little trial and error to find the sweet spot. The higher your diversion load the less "width" you will need.
thanks again for the helpful info.
got working on it today an heres the settings that i came out with. only had a chance to work on it while in flow mode today so well have to wait and see how absorb does tomorrow.
anyway.
my factory float setting is 26.8V the classic will stay in float mode within .4V then goes into Float MPPT.
my volt setting to keep me in the float parameters was 1.0
and my width setting to keep me in float was 1.0V
with these settings the classic keeps me at a constant 26.6V and stays in FLOAT. it seems that the lower i set the "voltage" the classic wanted to keep me at a voltage too low for float and was keeping me in float MPPT. the only setting that kept me within 0.2V of float was 1.0 "voltage".
also tried 1.0 "width" and worked well with the 1.0 "voltage" setting. tried 2.0 "width" but it just kept on aux 2 the entire time without pulsing on/off?
anyway conclusion is that the PWM waste not works great for harvesting that extra power (during float anyway). well see tomorrow if the setting i put in for float will work just as good for absorb.
all this got me thinking that this PWM diversion waste not is great but i do miss having WBjr to see my SOC%.
will i get the same result if i use a diversion controller (morningstar tristar 60) and just run everything straight DC?
i would like to have this "diversion" feature and still be able to use my WBjr with aux 2 from the classic, seems a diversion controller is the way to achieve both. any opinions on this? anyone try this out?
Maybe instead of putting money into another controller to do diversion you could buy more PV's and just connect them directly to heating element of water heater. That way you get 100% of power to water heater unless the water temperature gets to temp setpoint .
Larry
thanks larry looked into that route also, but, i cant seem to find a high voltage DC thermostat that can work with the setup so the water doesn't boil over.
i was looking into this but not sure if its even needed (looks like just need it to run the AC thermostat)
http://www.ebay.com/itm/302133928592?_trksid=p2055119.m1438.l2661&ssPageName=STRK%3AMEBIDX%3AIT
anyone think it's worth it or should i just connect the PV direct to the heating element and not worry about thermostat control?
but this still wouldn't solve the problem of the wasted power and being able to use the WBjr and PWM "waste not" at the same time!
looking into the tristar 45. going to try to use it in diversion mode directly off the batteries to the heating element and see if it can do the same as Aux 2 PWM "waste not hi". this would free up aux 2 for WBjr use!
these controllers would be perfect if you could just hook WBjr to AUX 1!
Inexpensive temperature controllers might work - you would run the small relay to higher rated SSR .
http://www.ebay.com/itm/DC12V-W1209-Temperature-Controller-Control-Switch-Waterproof-Digital-Display-/201315706969?hash=item2edf59e859:g:zjwAAOSw~otWfgyp
Larry
Quote from: kauaisolarman on November 09, 2016, 10:41:54 PM
thanks larry looked into that route also, but, i cant seem to find a high voltage DC thermostat that can work with the setup so the water doesn't boil over.
You need a temperatre controlled switch. These usually have a flat sensor area that presses onto the heat area to be measured such as copper pipe from tank top where hot water is supplied from.
This switch controls an ssr that connects the pvs to the heating element
These switches come in preset temperatures, I use a 65degC one.
The switch is normally closed and opens when preset temp is reached
Dgd
thank you sir.
any link to show what you mean? possibly where to purchase 1?
Quote from: dgd on November 10, 2016, 01:55:01 AM
Quote from: kauaisolarman on November 09, 2016, 10:41:54 PM
thanks larry looked into that route also, but, i cant seem to find a high voltage DC thermostat that can work with the setup so the water doesn't boil over.
You need a temperatre controlled switch. These usually have a flat sensor area that presses onto the heat area to be measured such as copper pipe from tank top where hot water is supplied from.
This switch controls an ssr that connects the pvs to the heating element
These switches come in preset temperatures, I use a 65degC one.
The switch is normally closed and opens when preset temp is reached
Dgd
Do you use this type Dgd ?
http://www.ebay.com/itm/Plastic-Head-40-130-Temperature-Control-Switch-Thermostat-Normal-Open-Closed-/371646622367?var=&hash=item5687dd6a9f:m:mN5KhKkwM3U1m7Fm_I6B-hw
Or this round type ?
http://www.ebay.com/itm/2-Pcs-149F-65C-KSD302-Normal-Close-NC-Temperature-Control-Switch-Thermostat-/231326554859?hash=item35dc231aeb:g:rlkAAOSwcLxYDjHd
Larry
hard thing is to find high voltage DC type thermostats.
i have read that if you put DV voltage through those AC thermostats they will burn up.
i see the 12-48VDC thermostats, but is you want to wire your panels in parallel for higher DC voltage they dont seem to be able to handle that.
thats the only reason i was looking at the DC-AC converter so i can run high voltage DC direct to the AC heating element/thermostat.
Quote from: kauaisolarman on November 10, 2016, 06:08:52 PM
hard thing is to find high voltage DC type thermostats.
i have read that if you put DV voltage through those AC thermostats they will burn up.
i see the 12-48VDC thermostats, but is you want to wire your panels in parallel for higher DC voltage they dont seem to be able to handle that.
thats the only reason i was looking at the DC-AC converter so i can run high voltage DC direct to the AC heating element/thermostat.
Dgd said he uses the little thermostat to a SSR - so the SSR is handling the higher DC voltage and current - not the thermostat . The thermostat would be able to work with a DC control voltage like 12v or lower .
Larry
Quote from: ClassicCrazy on November 10, 2016, 09:12:02 AM
Or this round type ?
http://www.ebay.com/itm/2-Pcs-149F-65C-KSD302-Normal-Close-NC-Temperature-Control-Switch-Thermostat-/231326554859?hash=item35dc231aeb:g:rlkAAOSwcLxYDjHd
Thats it. Very reliable too, i bought a few but the original is still working 2 years..
Dgd
so you wire the thermostat to the AUX side of the SSR inline with AUX 2 ?
and run the high voltage DC on the other end of the SSR connected directly to the PV array?
sorry i'm just not exactly sure how you have the AC thermostat connected to the DC power.
Dgd can correct me if I am wrong - you would wire Aux + in series with thermostat switch to + control contacts of SSR ( the other side of control contacts goes to ground for Aux. ) So if power is available on Aux it has to go through closed thermostat to activate the SSR. If water gets hot the normally closed contact of thermostat opens and shuts off SSR .
Your PV + goes to SSR load contacts to one side of the water heater element . The other side would go to PV negative. Depending on how you are feeding that PV if from system with Classic Dgd says he isolates it with the diode rectifier he described. If direct from a PV you wouldn't need any diode protection but should have it go through appropriate sized breaker.
Larry
thanks for clearing that up larry , but at that point what would "turn on" aux 1 to tell the SSR to send send power?
if the panels were connected directly to the heating element wouldn't you want them to always be putting power to the element and only stop when the tank reaches desired temperature? wouldn't you want the SSR to be "on" all/most of the time only turning off for max temps? what aux 1 for?
should SSR be connected in series to the battery (12V) and the temp sensor for continual "on" power? that way when sun is shining all power from solar panels go to heating element and only when temps are reached thermostat would stop power to SSR turning "off"solar panels?
is that correct way to do it? obviously with OCP between panels and heating element.
thanks again for the inputs
I should have clarified. If you are going direct from PV to water heater then you would not use AUX but use some other battery powered source of voltage to go through the thermostat control circuit. If you have a 12v battery that would work but could be less if SSR will operate on less. You could use any source of voltage for that - example wall wart as long as voltage and current is sufficient to operate SSR. And you would of course want to fuse the control circuit as well as have a breaker in the load circuit.
These are general wiring - read up in Arduino section for some other controls people have made.
Your original questions were about using Aux on Classic and Dgd described earlier how he has his wired up to take power from PV that is also connected to Classic.
Larry
I have used one of those 1.5 watt 12v solar trickle charge PVs, the type you often see for mounting in a car window and with cable/cig lighter connector. These tend to cost a couple of dollars.
Just connect thru ssr controls and temperature switch, include a 12v switch if you want manual control as well.
It will produce enough power to enable the SSR and only does this when there is sunshine!
dgd
thanks again everything making more and more sense every day.
so i currently am running AUX 2 "waste not HI" and here is where my dilemma is.
when i set the settings to 1.0V and 1.0 "width" the absorb stage work great for diverting excess power. it keeps me right at absorb voltage and can complete the entire absorb stage with this setting, however the problem comes when is Float.
with the 1.0/1.0 settings during absorb the most current that can be pulled is about 850 watts, but, there is more than this to be had. if i move the settings to 0.6V/1.0"width" during float then the controller can use the entire 1190 watts that the element can pull.
problem is if i leave the settings to 0.6/1.0 the next day the controller does not want to stay in absorb voltage. when absorb voltage hits aux 2 is putting too much power to the element and dropping voltage not allowing for absorb stage to start. then i need to reset to 1.0/1.0 for charging to be completed.
any thoughts on this?
i am currently running an AC heating element off my inverter with a max power of 1190W @ 120V.
kauaisolarman,
Did you get your water heater working with dgd's setup?
Hi David,
You might want to send a PM to kauaisolarman, as it looks like he has not been here for about six months.
FWIW, Vic