Classic water heater diversion

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  • SolarMusher
    SolarMusher Solar Expert Posts: 176 ✭✭✭
    #62
    Re: Classic water heater diversion
    Eric L wrote: »
    That's what I did. I put a 40 amp DC-DC solid state relay between the DC breaker and the dedicated inverter, and control it with the "Daylight" function on the AUX1 output of one of my Classics.



    My inverter is a PSW -- a second-hand Exceltech.

    One observation on the Magnum/Xantrex comparison. For me, it was very important to have an inverter that had a properly functioning grid support function, since my whole system was designed around a smaller battery bank. There are a lot of threads here about people having trouble with grid support and the XW line of inverters, including some really annoying issues like people being unable to get it to go completely off-grid (the XWs always draw like 100 watts or something from the grid when it is available).

    So for me, but presumably not for someone like Chris O. who I think is 100% off-grid, this was a deal-breaker. By contrast, the Magnum grid-integration worked flawlessly out of the box.

    Someone needs to make an inverter with the XW's guts and the Magnum's control system.
    Eric, could you post what were, from your experience, the Aux2 waste not width settings that gave the best results with your elements.
    It could help and save time on trials and errors when first playing with it.
    Thanks,
    Erik
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  • Eric L
    Eric L Solar Expert Posts: 262 ✭✭
    #63
    Re: Classic water heater diversion
    Eric, could you post what were, from your experience, the Aux2 waste not width settings that gave the best results with your elements.

    With the Magnum, the best setting for the pulse width was 3.0. With the Exceltech, it's 1.0. In PWM mode, if the inverters aren't delivering full voltage, they make a rattling, knocking, or other noise as the current pulses hit the transformer. By changing the pulse width setting in the Classic, you can reduce the intensity and frequency of this rattling noise, which also corresponded in my experience with a reduced voltage fluctuation at the output.

    I think I set the Magnum's voltage offset to just 1 volt. Wiith the smaller Exceltech, I've set it to 2.5v. This means the Exceltech comes on sooner and goes off later. Since the Exceltech is delivering 120 volts into a 4500 watt, 240 volt element, it's only providing 1100 watts at full on, so I want it to run longer; hence the wider offset.

    The Magnum would get my tank to 170 degrees within a few hours on a full-sun day. The Exceltech will not, unsurprisingly since it's running at lower power. However, it's at full voltage most of the time, and thus not pulsing, since once the batteries near absorb charge, my array is large enough to keep it going at 120 volts even in light cloud conditions. So after a sunny or partly-sunny day, the temp in the tank will be about 150 degrees. My top tank element is on grid power and is set to 120 degrees, while the bottom on solar and set to 170 (the max). The tank is also well-insulated. Consequently, I really don't think the top grid-connected element turns on very much. It will after a prolonged cloudy period, obviously, or if we have guests staying with us using a lot of HW.

    You've probably already figured this out, but you'll want to insulate your electric feeder tank well, as well as all the supply pipes.
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  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    #64
    Re: Classic water heater diversion
    Eric L wrote: »
    W while the bottom on solar and set to 170 (the max).
    I did not see this mentioned in a quick scan of the thread, so I want to make sure that readers remember that with a hot water temperature of 140F or higher you really need some sort of thermostatic anti-scald valve or tempering valve between the hot water tank and the point of use. The design of that is enough for a thread of its own, and I suspect they will find some good pointers if they search.
    SMA SB 3000, old BP panels.
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  • ChrisOlson
    ChrisOlson Banned Posts: 1,807 ✭✭
    #65
    Re: Classic water heater diversion

    inetdog - we put a blending valve on our water heater. It blends the hot with cold so 125 degree water comes out no matter how the hot the heaters are. We bought the blending valve for about $75.

    My PSX-240 was the problem with the pulsing when we had the 5548. Since we put in the XW I have set the width to 1.0 with no problems. I have my offset at -3.0, as that's what it takes to get full power to the element once the voltage reaches the charge stage set point. It also makes it take a little longer to get to absorb on a good day. But that's no big deal for us.

    I'd rather have the system heating at least some water on the marginal days when the RE can get the voltage up to 59.0, but there's not enough incoming to ever absorb the bank anyway. Rather than try to partially absorb the bank on those days, we just dump it into the water heaters instead. Eventually, the system catches up on a good day - and we never run out of hot water.
    --
    Chris
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  • ChrisOlson
    ChrisOlson Banned Posts: 1,807 ✭✭
    #66
    Re: Classic water heater diversion
    Eric L wrote: »
    One observation on the Magnum/Xantrex comparison. For me, it was very important to have an inverter that had a properly functioning grid support function, since my whole system was designed around a smaller battery bank. There are a lot of threads here about people having trouble with grid support and the XW line of inverters, including some really annoying issues like people being unable to get it to go completely off-grid (the XWs always draw like 100 watts or something from the grid when it is available).

    Admittedly I don't know much about grid-tie (as in nothing at all). I've always figured they build an inverter with dual AC inputs so you can hook two generators up to it :D

    The Magnum's primary market was RV's. And then they changed a few specs on them and started marketing them for off-grid or RE applications. The off-grid market is not that big. So few manufacturers are going to spend a lot of money on building a real off-grid inverter. I think the Magnums moved into the off-grid market because it was another marketing opportunity for them. And they do have a good reputation in the RV industry. But an inverter designed for RV application does not necessarily make an ideal off-grid inverter.

    The transformer in the XW weighs more than a whole Magnum inverter. So I think this power fluctuation problem that folks are having with the Magnums is probably the difference between "light duty" and "heavy duty".
    --
    Chris
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  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    #67
    Re: Classic water heater diversion
    ChrisOlson wrote: »
    Admittedly I don't know much about grid-tie (as in nothing at all). I've always figured they build an inverter with dual AC inputs so you can hook two generators up to it :D

    And "sell mode" was in case your neighbor wanted to hook up to your system? :-)
    SMA SB 3000, old BP panels.
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  • Photowhit
    Photowhit Solar Expert Posts: 6,006 ✭✭✭✭✭
    #68
    Re: Classic water heater diversion

    OK I've very late to the party, but am going back off grid next month (after threat of frost, wood stove will be installed over summer) I have lots off array, the 4000 watt that's up is about what is reasonable for my 24V 800Ah battery. I have another 2.6Kw off array and saw the same listing as "solar Musher" for the 1kw 48V element.

    I am willing to throw a few dollars and try it in my 30(maybe 40) gal water heater, before i switch to a 10-12 gallon water heater and run it off 120v ac.

    The element is solar by Missouri wind... since I was given bad info when I called them about a diversion CC, I'll have to cut off 3 fingers just to buy the element. They of course give no range of voltages, their video says you can just hook up panels directly....

    ...So what is going to happen if I hook up 1440 watts (8 - 185 watt suntech) panels so I have roughly the correct amount of amperage on a 'normal' day run in pairs at 70 volts (true 24 volt panels) Will I destroy the element? Should I use less panels? If recover for the hot water heater is 40 minutes with 5500watts, will a 1000 watts heat the water over the course of a sunny day?

    I'm a single guy and I usually run the WH once every couple days and get 3 events - showers, a wash dishes before I have to heat water again. I also thought about putting a 110 - 1500 watt element in the top of the WH, top run off the inverter... The solar would likely be an ungrounded system at least during a trial. I can shower at work, work security in a uniform so before work is my normal time.

    I would be willing to do the SSR and a inverter, but not until they have the battery monitor module, since I'll be running A/C's over summer I can't imagine what info my poor Classics will be looking like. I usually can figure out what the profile would look like but this will be interesting with so much going on. Really feel since our heat comes with sun that I should be fine with my minimal storage (can't imagine having said 9+Kwh of storage as minimal even 2 years ago)

    It's late any ideas would be helpful. I guess the heating elements are pure resistance so I could use the 220v elements that exist, but the math hurts my head anymore...
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
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  • SolarMusher
    SolarMusher Solar Expert Posts: 176 ✭✭✭
    #69
    Re: Classic water heater diversion

    Hi Photo,
    The element is solar by Missouri wind... since I was given bad info when I called them about a diversion CC, I'll have to cut off 3 fingers just to buy the element. They of course give no range of voltages, their video says you can just hook up panels directly....
    I would not trust in that 48V element sold by MWS, as Solarvic said at the begining of this thread it seems that they just forget that one needs to tight the element to make it works...
    ...So what is going to happen if I hook up 1440 watts (8 - 185 watt suntech) panels so I have roughly the correct amount of amperage on a 'normal' day run in pairs at 70 volts (true 24 volt panels) Will I destroy the element? Should I use less panels? If recover for the hot water heater is 40 minutes with 5500watts, will a 1000 watts heat the water over the course of a sunny day?
    I will go with AC elements rather than DC, they are cheaper and it doesn't matter if the source is DC or AC. With 1440W/70V PV, you could go with 2x 3000W/120V elements, you'll have at the end 2x 750W on 70V at the elements, roughly 25%.
    Here are the maths: 1.5kw at120v=12.5amps=9.5ohms element, 60v puts 6.25amps into 9.5ohms giving 375watts (from Dgd post on MN forum).
    Mtdoc used a Geyser heater pump to heat a 40Gal tank (Nyle, 800$) and had very good results (grid-tie), this pump draws 600/800W on your inverter. With all the PV you have, you could use it on Aux float of your Classic for off-grid use. I'm sure that it could work great for you!
    Good luck with your project and don't forget to report,
    Erik
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  • SolarMusher
    SolarMusher Solar Expert Posts: 176 ✭✭✭
    #70
    Re: Classic water heater diversion
    Eric L wrote: »
    With the Magnum, the best setting for the pulse width was 3.0. With the Exceltech, it's 1.0. In PWM mode, if the inverters aren't delivering full voltage, they make a rattling, knocking, or other noise as the current pulses hit the transformer. By changing the pulse width setting in the Classic, you can reduce the intensity and frequency of this rattling noise, which also corresponded in my experience with a reduced voltage fluctuation at the output.

    I think I set the Magnum's voltage offset to just 1 volt. Wiith the smaller Exceltech, I've set it to 2.5v. This means the Exceltech comes on sooner and goes off later. Since the Exceltech is delivering 120 volts into a 4500 watt, 240 volt element, it's only providing 1100 watts at full on, so I want it to run longer; hence the wider offset.

    The Magnum would get my tank to 170 degrees within a few hours on a full-sun day. The Exceltech will not, unsurprisingly since it's running at lower power. However, it's at full voltage most of the time, and thus not pulsing, since once the batteries near absorb charge, my array is large enough to keep it going at 120 volts even in light cloud conditions. So after a sunny or partly-sunny day, the temp in the tank will be about 150 degrees. My top tank element is on grid power and is set to 120 degrees, while the bottom on solar and set to 170 (the max). The tank is also well-insulated. Consequently, I really don't think the top grid-connected element turns on very much. It will after a prolonged cloudy period, obviously, or if we have guests staying with us using a lot of HW.

    You've probably already figured this out, but you'll want to insulate your electric feeder tank well, as well as all the supply pipes.
    Eric and Chris, thanks a lot for sharing your experiences with details. I'm sure that it will give ideas to many of us who would like to stop wasting energy while keeping our batteries healthy.
    Erik
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  • ChrisOlson
    ChrisOlson Banned Posts: 1,807 ✭✭
    #71
    Re: Classic water heater diversion
    Eric L wrote: »
    One observation on the Magnum/Xantrex comparison. For me, it was very important to have an inverter that had a properly functioning grid support function

    Someone needs to make an inverter with the XW's guts and the Magnum's control system.

    Eric, your needs for grid-tie are equivalent in importance to me for off-grid. The one anomaly I've found with the XW is in Load Start for the generator. I've adjusted our loads to be pretty nicely balanced on L1 and L2. But there are some situations involving a Multi-Tasking Woman that can cause my blood pressure to rise.

    L2 will overload if my wife turns on her Super Turbo Pro Megawatt Hair Dryer, the microwave, the water heater, and the washing machine all at the same time. I never thought this was possible. But she went to the basement and put clothes in the washer. Then takes a shower and cause the water heater to kick in for recovery due to high hot water demand. Then she gets out of the shower and decides she's hungry. So she puts me into a near-death coma by walking out in the kitchen with nothing on and puts food in the microwave. Then she goes back into the bathroom and fires up the Super Turbo Pro Megawatt.

    Now the inverter is overloaded on L2. Big Time. The inverter has to endure this punishment for five minutes before it can give XW-AGS the go ahead to fire the generator up and help out. That time is not adjustable like it was in the SW Plus. My wife spends five minutes giving her hair the Wind Blown Blonde Babe look, and finally the XW-AGS starts the generator. Just as it starts it my wife turns off the Super Turbo Pro Megawatt. The Load Amps drops below the shutdown threshold. The inverter loads the generator for about 30 seconds. The shutdown delay is 1 minute (again, not adjustable like it was in the SW Plus). 30 seconds of load time on the generator and it disconnects it, goes into cool-down and shuts it off.

    It would be nice if they would make those Load Start times adjustable.
    --
    Chris
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  • NorthGuy
    NorthGuy Solar Expert Posts: 1,913 ✭✭
    #72
    Re: Classic water heater diversion
    ChrisOlson wrote: »
    It would be nice if they would make those Load Start times adjustable.

    I've heard that XW Config tool may be used to adjust lots of things that are not normally adjustable, bu I'm not sure what exactly you can adjust.
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  • ChrisOlson
    ChrisOlson Banned Posts: 1,807 ✭✭
    #73
    Re: Classic water heater diversion

    I'll ask my dealer about that. But I thought XW Config Tool was merely a PC interface to what you got in the SCP, that makes it easier and quicker to set up multiple inverters.
    --
    Chris
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