Series Piped Water Heaters - Opportunity Load and Propane

Anawa
Anawa Solar Expert Posts: 225 ✭✭✭
I'm finalizing installation of my off-grid installation and looking to set-up a water heating system. Currently hooking-up Outback FW500 system and will start with AC sub panel next week.

I would like to pipe a couple of 40 gallons units in series - one electrical and the other propane. I anticipate being able to frequently generate excess power for an opportunity load. I have been unable to find much info on the NAWS forum to review on such a configuration. I would appreciate some guidance on this undertaking, before I get to deep in the process and waste both time and money.

System configuration: Off-grid, 48 volt, 4.59 kW array, Outback FX3648 (2), Outback FM 80 (2), 800 Ah industrial battery bank.

Thanks
Anawa
Paul 
in Georgia

System 1: PV- 410w Evergreen, Mppt- Blue Sky Solar Boost, Batt - 225ah Deka AGM, 12v led house lighting,
System 2: PV- 215w Kyocera, PWM - Morningstar PS30, Batt- 225ah Deka GC's, 12v led house lighting, Dankoff 12v water pump,
System 3: PV- 1.5kw Kyocera, Grundfos 11 SQF well pump, 3000 gal above ground water storage, dom water & irrigation,
System 4: PV- 6.1kw Kyocera, Mppt- Outback FM80-2ea, Inverter- Outback FX3648-2ea, Batt- 804ah GB traction, Grundfos BMQE booster pump 240v, Mitsibushi mini-splits 240v, 18k and 15k
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Comments

  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Is the propane a standard tanked propane heater or tankless?

    Are you planning on using a 120 or 240 VAC heating element or a 48 VDC element for the electric heater?

    Will this be an "optional" dump load or a non-optional dump load (like for a wind/water turbine)?

    Would a heat pump type system be worth the money for you (generate 2x or more hot water during "warm" (over 55F or so) weather?

    water.nyle.com/residential/

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Anawa
    Anawa Solar Expert Posts: 225 ✭✭✭
    The propane water heater is a standard 40 gallon unit.

    Looking to use the Outback DC 48 volt power source for the load with a standard 120 volt 2400-3000 watt heating element. I am aware that using the 120 volt element will produce only about 400-600 watts.

    My system design probably prohibits the heat-pump water heating system as a cost effective alternative. I'm okay with propane being the "primary" water heating source. I am already using propane for cooking and have installed the in-ground tank.

    Are there any previous posts on the forum about opportunity loads for water heating? I've unsuccessfully tried using the search feature to no avail.

    Thanks
    Anawaf
    Paul 
    in Georgia

    System 1: PV- 410w Evergreen, Mppt- Blue Sky Solar Boost, Batt - 225ah Deka AGM, 12v led house lighting,
    System 2: PV- 215w Kyocera, PWM - Morningstar PS30, Batt- 225ah Deka GC's, 12v led house lighting, Dankoff 12v water pump,
    System 3: PV- 1.5kw Kyocera, Grundfos 11 SQF well pump, 3000 gal above ground water storage, dom water & irrigation,
    System 4: PV- 6.1kw Kyocera, Mppt- Outback FM80-2ea, Inverter- Outback FX3648-2ea, Batt- 804ah GB traction, Grundfos BMQE booster pump 240v, Mitsibushi mini-splits 240v, 18k and 15k
  • Anawa
    Anawa Solar Expert Posts: 225 ✭✭✭
    Maybe I just need someone to instruct me how to use the search function on this forum to find what I'm looking for. I'm sure something has been previously posted on this subject.

    Anawa
    Paul 
    in Georgia

    System 1: PV- 410w Evergreen, Mppt- Blue Sky Solar Boost, Batt - 225ah Deka AGM, 12v led house lighting,
    System 2: PV- 215w Kyocera, PWM - Morningstar PS30, Batt- 225ah Deka GC's, 12v led house lighting, Dankoff 12v water pump,
    System 3: PV- 1.5kw Kyocera, Grundfos 11 SQF well pump, 3000 gal above ground water storage, dom water & irrigation,
    System 4: PV- 6.1kw Kyocera, Mppt- Outback FM80-2ea, Inverter- Outback FX3648-2ea, Batt- 804ah GB traction, Grundfos BMQE booster pump 240v, Mitsibushi mini-splits 240v, 18k and 15k
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    I have to go right now.... But plug the following search into Google and it should give you better answers:

    site:forum.solar-electric.com outback opportunity loads

    The "site:" tag tells Google to limit searches just to this web forum.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Blackcherry04
    Blackcherry04 Solar Expert Posts: 2,490 ✭✭✭
    Heating water is all about temperature rise, say from 50° to 115° +. Since you have no idea at this point what your solar production will be it's hard to plumb them in a hard configuration. One is the tempering tank and one the outflow tank ( Master and Slave ). It is best to use 3 way valves so you can switch them, or set up a by-pass of some kind. The propane would be the master and the solar the slave. You should leave it so you can switch their position in the summer and winter as they may change seasonally it's best. Another issue is having a tempering / mixing valve to control the temperature of the Hot water if the Solar climbs above the safe limit of say 120° or so.

    The main idea is to cut the temperature differential, how you do it is not important.
  • solorone
    solorone Solar Expert Posts: 257 ✭✭✭
    Thought I would speak to the plumbing end of this plan. Not sure if you intend to have a valve between the two tanks. seems like it would be needed due to prevent possible uneven water supply. But read up siphon draw, as I recall from some of my commercial projects the piping to multiple water heaters can be tedious and tricky, precise leveling of tanks and pipes, to make them share equally in the hot water supply.
  • solar_dave
    solar_dave Solar Expert Posts: 2,397 ✭✭✭✭
    My solar thermal system is set up that way with serial plumbed tanks, an 80 gallon for the solar thermal collector and a 50 gallon nat gas as primary. The solar thermal tank can go as high as 150F and the output of the nat gas to the house has a mixing valve to control the temp of the output water. The nat gas rare runs from Feb through Nov. and I turn down the trigger point in summer.

    Down here freezing is not an issue. In fact the controller, a Goldline, pumps warm water to the collector in the event the outdoor temp hits 40F. I see that only a couple mornings in Dec. and Jan.

  • Anawa
    Anawa Solar Expert Posts: 225 ✭✭✭
    Thanks guys, you all have been helpful in refining what I need to configure my system.

    Finally figured out how to find wiring and load information on my water heating questions by using the search feature on the forum. Using "SSR" in the search field, many threads came up.

    Anawa
    Paul 
    in Georgia

    System 1: PV- 410w Evergreen, Mppt- Blue Sky Solar Boost, Batt - 225ah Deka AGM, 12v led house lighting,
    System 2: PV- 215w Kyocera, PWM - Morningstar PS30, Batt- 225ah Deka GC's, 12v led house lighting, Dankoff 12v water pump,
    System 3: PV- 1.5kw Kyocera, Grundfos 11 SQF well pump, 3000 gal above ground water storage, dom water & irrigation,
    System 4: PV- 6.1kw Kyocera, Mppt- Outback FM80-2ea, Inverter- Outback FX3648-2ea, Batt- 804ah GB traction, Grundfos BMQE booster pump 240v, Mitsibushi mini-splits 240v, 18k and 15k
  • Photowhit
    Photowhit Solar Expert Posts: 6,002 ✭✭✭✭✭
    Anawa wrote: »
    Looking to use the Outback DC 48 volt power source for the load with a standard 120 volt 2400-3000 watt heating element. I am aware that using the 120 volt element will produce only about 400-600 watts.

    I believe the relationship is an inverse square, so half the voltage is 1/4 the wattage. I'm running a 3600 watt 240v element on 120v and it runs around 900watts. You have a good size array/system and might suggest using 120 v AC if your worried about the voltage drop and the opportunity load bouncing on and off at 240 volts.

    I think I found more info at Midnite's forum, so I suspect Outback's forum might have some info as well...
    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.
  • jonr
    jonr Solar Expert Posts: 1,386 ✭✭✭✭
    I'm curious - what device will detect that you have excess power available and modulate the current flow to the water heater accordingly?

    I am available for custom hardware/firmware development

  • Anawa
    Anawa Solar Expert Posts: 225 ✭✭✭
    Good question, jonr and it brings me to my next post. I, too, would like some thoughts on which device to select for the programming.

    If I understand the Outback FP1 system correctly, the Mate3 communication port is programmed to close (or open) a low voltage auxiliary port based upon high/low battery voltage and/or battery SOC. Auxiliary ports are available on both FM controllers, both FX inverters, and the FlexNet DC monitor and all these devices are connected to the Mate3 thru the Hub communication device. I'm not sure which would be the most appropriate aux port to use and would like some advice on the selection from forum contributors. Perhaps it does not matter which device you use for the sending the high/low aux signal becuase the battery status info comes from a single source and the Hub can send that data to any of the devices. Is this logic accurate or am I off?

    The "selected" aux port is then wired to a Solid State Relay (SSR) that opens and closes the circuit to the water heater. More questions then arise for me on this circuitry. Such as; Is it better to power the circuit with DC to avoid using the inverters?,
    If DC, what is the maximum voltage, 48-59? (my battery bank is 48 volts),
    Is the maximum amperage determined by element selection?
    What are the primary considerations to properly spec a SSR?

    Anawa
    Paul 
    in Georgia

    System 1: PV- 410w Evergreen, Mppt- Blue Sky Solar Boost, Batt - 225ah Deka AGM, 12v led house lighting,
    System 2: PV- 215w Kyocera, PWM - Morningstar PS30, Batt- 225ah Deka GC's, 12v led house lighting, Dankoff 12v water pump,
    System 3: PV- 1.5kw Kyocera, Grundfos 11 SQF well pump, 3000 gal above ground water storage, dom water & irrigation,
    System 4: PV- 6.1kw Kyocera, Mppt- Outback FM80-2ea, Inverter- Outback FX3648-2ea, Batt- 804ah GB traction, Grundfos BMQE booster pump 240v, Mitsibushi mini-splits 240v, 18k and 15k
  • jonr
    jonr Solar Expert Posts: 1,386 ✭✭✭✭
    You could probably get close to optimal by sensing array voltage and when it is consistently above V-MPP, add some load. Perhaps direct from the panels to the load. Note that SSRs are too slow to modulate current flow effectively and most don't handle DC. But a mosfet would work.

    I am available for custom hardware/firmware development

  • Photowhit
    Photowhit Solar Expert Posts: 6,002 ✭✭✭✭✭
    jonr wrote: »
    I'm curious - what device will detect that you have excess power available and modulate the current flow to the water heater accordingly?

    While it won't "modulate the current flow" the midnite classic also can turn on and off a load. Usually people choose to do this once the batteries reach the 'float' stage or fully charged, but I believe you can choose to start loads earlier. I don't have mine setup yet. While there are past discussion here, check out the Midnite forum for more complete information.

    The reason I suggested using 120v heating element is that this should be able to run just on the excess energy without drawing from the battery. At 240v 3000watt + energy will be drawn from the battery dropping the voltage to a point that it would likely change/restart the charging cycle.
    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.
  • Anawa
    Anawa Solar Expert Posts: 225 ✭✭✭
    I've been researching SSR's and found that Crydom has mosfet units that are designed for DC output. I'm wondering if this may be an option for my situation.

    Here is a link: http://www.crydom.com/en/Products/Catalog/d_06d.pdf

    They cost about $90 bucks (without heat sink). Anyone familiar with this product in this application?

    Thanks
    Anawa
    Paul 
    in Georgia

    System 1: PV- 410w Evergreen, Mppt- Blue Sky Solar Boost, Batt - 225ah Deka AGM, 12v led house lighting,
    System 2: PV- 215w Kyocera, PWM - Morningstar PS30, Batt- 225ah Deka GC's, 12v led house lighting, Dankoff 12v water pump,
    System 3: PV- 1.5kw Kyocera, Grundfos 11 SQF well pump, 3000 gal above ground water storage, dom water & irrigation,
    System 4: PV- 6.1kw Kyocera, Mppt- Outback FM80-2ea, Inverter- Outback FX3648-2ea, Batt- 804ah GB traction, Grundfos BMQE booster pump 240v, Mitsibushi mini-splits 240v, 18k and 15k
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    In general, I believe that Crydom is a good manufacturer... However, be very careful, there are apparently a lot of fake units on EBay/etc... If you find a price that is too good to be true--It probably is.

    http://www.instructables.com/id/The-inner-workings-of-Counterfeit-FOTEK-SSRs/?lang=de

    http://www.ebay.com/itm/261125660922?rmvSB=true
    This Fotek SSR was bought on ebay from a counterfeiter in china along with several others, every one has been a knock off to this date. as you can see from the pictures
    there is no way it could be a 40 amp relay with what is inside. the heat speader is thin and the actual "ssr" in side is way to small.
    This one fried in 10 minutes under 2/3rds load even with a massive heat sink and fan on it.
    and there was no control of amperage going through it with a 500k pot on it.
    If your looking for an ssr, don't waste your time with these ones.
    This listing is posted to save others from wasting money on P.O.S.'s
    When I confronted the seller for this item with emails I didn't get a response.
    I have bought from several different sellers in china and have yet to find a real fotek ssr
    notice the generous application of hot glue inside to give it some weight!
    If anyone has an issue with this listing or complains it's probably because they are
    selling fakes.
    To make this a "legal" auction I'm "selling" information, the info contained in this auction
    and recommendation on which ssr's would be better if your looking to buy cheaper ones than
    american made. you can look at my feedback and see who I purchased from recently, this is in no
    way endorsement to the other seller but I've bought from them a few times and did full rating
    stress test with no failures yet. good luck with what ever your building and happy hunting(parts hunting that is).
    update: I noticed that my feedback does not show the last set I bought, which was from this last week
    since no feedback has been left yet. I buy the Kyotto SSR's from Taiwan. The ones that I have gotten
    have all heald up to a full hr. at max rating with only a heat sink on them. The test specs are as follows:
    2 - 5500watt 240v water heater elements
    amperage and voltage meter with current transformer and clamp meter for measuring.
    1 Kyotto 40amp resistants controlled SSR with a 500k pot. and 1 lb. heatsink.
    test time: 1hr 15minutes - 10 minutes at 1/2load, 1hr at max 40amps as meassured from both meters, then 5 minutes of varying from 1-40amps testing it's ability to control the current
    after 1hr. burn in. and yes two 5500watt elements are capable of drawing 45amps, I wanted to have the ability of testing them at max +, the ammeter w/current transformer has a 5:1 ratio
    and has a range of 0-50amps, clamp meter is a fluke with 0-1000, set to 200 range while testing. 40amps is set on the lowest reading between the two(fluke meter) and the other is within
    a couple tenths.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Photowhit
    Photowhit Solar Expert Posts: 6,002 ✭✭✭✭✭
    Not sure why you would want to run 48 volts DC? Will you run a dedicated 48 volt line from your batteries to the water heater? You likely have 120 v AC there already(or 1 leg of a 240), you could run minimal wiring to run the relay and run AC. You have close to enough array to not worry about drawing from the battery and you could move to a 1500-1800watt element if need be... Less wiring, quicker heating, looks like a win-win to me. Perhaps you have some large loads running during the day?
    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.
  • westbranch
    westbranch Solar Expert Posts: 5,183 ✭✭✭✭
    search for posts by Keyturbocars and Crymdon...
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • jonr
    jonr Solar Expert Posts: 1,386 ✭✭✭✭
    You could PWM it at around 1Khz, but I'd expect the amp rating to go down (more heat). If simple on/off is OK, then up to 60VDC and 100A.

    I am available for custom hardware/firmware development

  • Anawa
    Anawa Solar Expert Posts: 225 ✭✭✭
    Jonr, your're way over my knowledge level on this issue. Please bare with me, I going to need help in understanding your last post. I'm not sure what you're telling me. What would I do to get "1khz" from which "PWM"? Does this have anything to do with the Crydom SSR, or are you suggesting another option?
    Thanks
    Anawa
    Paul 
    in Georgia

    System 1: PV- 410w Evergreen, Mppt- Blue Sky Solar Boost, Batt - 225ah Deka AGM, 12v led house lighting,
    System 2: PV- 215w Kyocera, PWM - Morningstar PS30, Batt- 225ah Deka GC's, 12v led house lighting, Dankoff 12v water pump,
    System 3: PV- 1.5kw Kyocera, Grundfos 11 SQF well pump, 3000 gal above ground water storage, dom water & irrigation,
    System 4: PV- 6.1kw Kyocera, Mppt- Outback FM80-2ea, Inverter- Outback FX3648-2ea, Batt- 804ah GB traction, Grundfos BMQE booster pump 240v, Mitsibushi mini-splits 240v, 18k and 15k
  • Dave Angelini
    Dave Angelini Solar Expert Posts: 6,728 ✭✭✭✭✭✭
    Anawa wrote: »
    Jonr, your're way over my knowledge level on this issue. Please bare with me, I going to need help in understanding your last post. I'm not sure what you're telling me. What would I do to get "1khz" from which "PWM"? Does this have anything to do with the Crydom SSR, or are you suggesting another option?
    Thanks
    Anawa


    My humble opinion is that you can waste more money, time, and possibly damage your system trying to heat water this way. The sun is out there, I would use it to heat the water directly.
    "we go where power lines don't" Sierra Nevada mountain area
       htps://offgridsolar1.com/
    E-mail offgridsolar@sti.net

  • Photowhit
    Photowhit Solar Expert Posts: 6,002 ✭✭✭✭✭
    My humble opinion is that you can waste more money, time, and possibly damage your system trying to heat water this way. The sun is out there, I would use it to heat the water directly.

    For the most part you can't heat water directly in areas that Fall much below freezing, So it involves heat exchangers and specialized water heaters and still requires a back up heater.

    I looked at running DC direct and decided it was too much to do a stand alone system and plan on running a 120volt AC water heating element as an opportunity load. I do wish the OP would explain why it is better to run DC wires, run an element that will require such long heating times, when he has a sizable system and 120 wires available. just run some network wires to run the relay and every thing is in place for the most part.

    Not sure how he could damage his system? I guess if the waste not or aux modes didn't work he might drain his battery, but haven't heard of that...
    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.
  • Anawa
    Anawa Solar Expert Posts: 225 ✭✭✭
    Photowhit, not sure who or what the "OP" is, but if it's me, I'm not dedicated to DC or AC for that matter. I'm just trying to figure out a cost effective and sensible solution to heating water with the system I have. You make a very convincing argument for going with AC and it seems no one is supporting the DC alternative with any definitive information.

    I'm a novice with this stuff, but too me, it seems that a direct DC load that acheives the intended goal (heat water) and not utilize the inverters is more efficient and would conserve energy. I agree with you that a stand-alone and dedicated array just to heat water is not an economical approach. I'm not trying to do that. Maybe I'm dead wrong about this, but I thought it was possible to wire the circuitry to draw directly from the batteries in my current configuration and by-pass the inverters. This is the approach I'm exploring. Any help to flesh-out such a configuration would be greatly appreciated. Likewise, if this approach is not practical, I would like to know that too.

    Thanks
    Anawa
    Paul 
    in Georgia

    System 1: PV- 410w Evergreen, Mppt- Blue Sky Solar Boost, Batt - 225ah Deka AGM, 12v led house lighting,
    System 2: PV- 215w Kyocera, PWM - Morningstar PS30, Batt- 225ah Deka GC's, 12v led house lighting, Dankoff 12v water pump,
    System 3: PV- 1.5kw Kyocera, Grundfos 11 SQF well pump, 3000 gal above ground water storage, dom water & irrigation,
    System 4: PV- 6.1kw Kyocera, Mppt- Outback FM80-2ea, Inverter- Outback FX3648-2ea, Batt- 804ah GB traction, Grundfos BMQE booster pump 240v, Mitsibushi mini-splits 240v, 18k and 15k
  • Photowhit
    Photowhit Solar Expert Posts: 6,002 ✭✭✭✭✭
    Anawa wrote: »
    Photowhit, not sure who or what the "OP" is, but if it's me, I'm not dedicated to DC or AC for that matter. I'm just trying to figure out a cost effective and sensible solution to heating water with the system I have. You make a very convincing argument for going with AC and it seems no one is supporting the DC alternative with any definitive information.

    I'm a novice with this stuff, but too me, it seems that a direct DC load that acheives the intended goal (heat water) and not utilize the inverters is more efficient and would conserve energy. I agree with you that a stand-alone and dedicated array just to heat water is not an economical approach. I'm not trying to do that. Maybe I'm dead wrong about this, but I thought it was possible to wire the circuitry to draw directly from the batteries in my current configuration and by-pass the inverters. This is the approach I'm exploring. Any help to flesh-out such a configuration would be greatly appreciated. Likewise, if this approach is not practical, I would like to know that too.

    Thanks
    Anawa

    OP is forum abbreviation for original poster.

    I was only considering a DC stand alone because I'm over paneled already and have 2600watts of new panels, that I got for $1000. I guess I've given up on the idea and will continue with a 3rd CC (charge controller) wired into my system and limit current so I can have better charging on overcast days. I already run AC water heating as an opportunity load on sunny days, just switching it on when I head into work and it shuts off via thermostat. The 3600watt 240V element runs at about 900watts at 120 volts.

    My current plan is to run the water heater off a relay controlled by the Midnite classic CC. I would let it start once the batteries had reach float. With my current 4,000 watt array I have enough wattage available to run my inverter(1800watts) on sunny days at full capacity with out worrying about voltage drop, but the only thing on other than the water heater would be my fridge and a few ghost loads maybe 1100watts max. If it becomes cloudy the charge controller will shut down the relay and start back up after a short period of time. I think you have to set it up for this, can't recall. I think you have a similar size array and though I'm not familiar with the Outback system, I would think it works similar.

    Manually turning it on I don't have trouble maintaining warm enough water to shower 7-8 months of the years, I will still have issues in the fall and long cloudy periods in the winter. With the water at under around 40 degrees it took over 6 hours for the thermostat to shut off this winter(after returning from vacation) But normally 2-3 hours when I have water in the 70+range, I actually have the thermostat set pretty low still, legacy from having this place on the grid almost 2 years ago. Also note I'm a single guy, Using 2-3 gallons in a camp shower off the wood heater in the winter time won't cut it for some/most! ...but I want to avoid gas if possible...
    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.
  • Anawa
    Anawa Solar Expert Posts: 225 ✭✭✭
    Photowhit, Thanks for the info on your set-up. What are the primary considerations that determine how much time delay before re-starting the relay?
    Anawa
    Paul 
    in Georgia

    System 1: PV- 410w Evergreen, Mppt- Blue Sky Solar Boost, Batt - 225ah Deka AGM, 12v led house lighting,
    System 2: PV- 215w Kyocera, PWM - Morningstar PS30, Batt- 225ah Deka GC's, 12v led house lighting, Dankoff 12v water pump,
    System 3: PV- 1.5kw Kyocera, Grundfos 11 SQF well pump, 3000 gal above ground water storage, dom water & irrigation,
    System 4: PV- 6.1kw Kyocera, Mppt- Outback FM80-2ea, Inverter- Outback FX3648-2ea, Batt- 804ah GB traction, Grundfos BMQE booster pump 240v, Mitsibushi mini-splits 240v, 18k and 15k
  • Anawa
    Anawa Solar Expert Posts: 225 ✭✭✭
    BTW, I've been called worse things than an "OP".
    Anawa
    Paul 
    in Georgia

    System 1: PV- 410w Evergreen, Mppt- Blue Sky Solar Boost, Batt - 225ah Deka AGM, 12v led house lighting,
    System 2: PV- 215w Kyocera, PWM - Morningstar PS30, Batt- 225ah Deka GC's, 12v led house lighting, Dankoff 12v water pump,
    System 3: PV- 1.5kw Kyocera, Grundfos 11 SQF well pump, 3000 gal above ground water storage, dom water & irrigation,
    System 4: PV- 6.1kw Kyocera, Mppt- Outback FM80-2ea, Inverter- Outback FX3648-2ea, Batt- 804ah GB traction, Grundfos BMQE booster pump 240v, Mitsibushi mini-splits 240v, 18k and 15k
  • SolarMusher
    SolarMusher Solar Expert Posts: 176 ✭✭✭
    Anawa wrote: »
    Photowhit, not sure who or what the "OP" is, but if it's me, I'm not dedicated to DC or AC for that matter. I'm just trying to figure out a cost effective and sensible solution to heating water with the system I have. You make a very convincing argument for going with AC and it seems no one is supporting the DC alternative with any definitive information.

    I'm a novice with this stuff, but too me, it seems that a direct DC load that acheives the intended goal (heat water) and not utilize the inverters is more efficient and would conserve energy. I agree with you that a stand-alone and dedicated array just to heat water is not an economical approach. I'm not trying to do that. Maybe I'm dead wrong about this, but I thought it was possible to wire the circuitry to draw directly from the batteries in my current configuration and by-pass the inverters. This is the approach I'm exploring. Any help to flesh-out such a configuration would be greatly appreciated. Likewise, if this approach is not practical, I would like to know that too.

    Thanks
    Anawa

    As others said, what do you want to do with this preheater? Just warm it? If that's what you want, DC is a good choice if the heater is not too far from your batteries. 3000 watts/120V elements are the most powerful that you can find but they'll only give you 650 watts when used at 60Vdc (absorb) or 1300 watts if used simultaneously with 2x thermostats and 950/1000 watts when in Float at 53/54Vdc. You'll have better results with real 60V elements (1265 watts) non-simultaneous but they are pricey. As Photowhit said, it works great on Aux with a Classic or Outback FM controller and crydom SSR D1D40 on heatsink but it's will take 6 hours on abs/float to heat a 40Gls tank to 120°F (if you don't use hot water when heating...). I'm pretty sure that you won't be satisfied with the result and that you'll want a system that can heat seriously in less than 3 hours even if you have to use some hot water. Then, you'll have no other choices to make it AC with 2000 watts/120V elements through an inverter and you will need to use a PWM Aux (don't recall the Outback name for that but you have it in the FM menus). Problem #1! It will make your lights and other eletronics to flicker because of the PWM signal (Pulse With Modulation). Problem #2, you will need to get another cheap (2500 watts) 48V MSW inverter to make it work (not easy to find) or buy a Classic and use Aux1 wastenot non PWM to get it through your VFX x2. You'll find quickly that this Classic Aux1 is not that great (full power or nothing).
    My advice: You've a powerfull array, follow the AC road, buy a cheap MSW inverter, use FM PWM aux with a Crydom AC SSR/heatsink or from another good quality manufacter.
    Good luck and be safe.
    Erik
  • Anawa
    Anawa Solar Expert Posts: 225 ✭✭✭
    SolarMusher, this is exactly the information I've been looking for! Very succinct and only essential commentary. Thanks.

    Now, if y'all will 'cuse me for a while, I'll just step behind the barn and ponder my water heating situation.

    Anawa
    Paul 
    in Georgia

    System 1: PV- 410w Evergreen, Mppt- Blue Sky Solar Boost, Batt - 225ah Deka AGM, 12v led house lighting,
    System 2: PV- 215w Kyocera, PWM - Morningstar PS30, Batt- 225ah Deka GC's, 12v led house lighting, Dankoff 12v water pump,
    System 3: PV- 1.5kw Kyocera, Grundfos 11 SQF well pump, 3000 gal above ground water storage, dom water & irrigation,
    System 4: PV- 6.1kw Kyocera, Mppt- Outback FM80-2ea, Inverter- Outback FX3648-2ea, Batt- 804ah GB traction, Grundfos BMQE booster pump 240v, Mitsibushi mini-splits 240v, 18k and 15k
  • SolarMusher
    SolarMusher Solar Expert Posts: 176 ✭✭✭
    Anawa wrote: »
    SolarMusher, this is exactly the information I've been looking for! Very succinct and only essential commentary. Thanks.

    Now, if y'all will 'cuse me for a while, I'll just step behind the barn and ponder my water heating situation.

    Anawa

    If you want to take the DC road, use the manufacturer's mecanical thermostat to switch the positive aux wire only (12V signal) and use one or two ssr to switch current to the elements at 60V. I've done it with 2x eco thermostats for safety and 2x ssr/heatsink for cooler operation. Each load has its own 30A breaker located in a remote Midnite combiner box close to the water heater. Some will add a diode between pos/neg of the loads to protect the controller.
    As said, works nice but slow. Take water from a frozen lake and its a looong way to get it warm . It will be better with longer sunny days when the lake will be a bit warmer :cool:.
    Always great to see that propane heater resting at sunset!
    Erik
  • Photowhit
    Photowhit Solar Expert Posts: 6,002 ✭✭✭✭✭
    My advice: You've a powerfull array, follow the AC road, buy a cheap MSW inverter, use FM PWM aux with a Crydom AC SSR/heatsink or from another good quality manufacter.

    Eirk, I'm not following you, why can't he just use his existing inverter? Switch on the ac via relay off the controller? I'm working day time hours now so may get off my backside and set this up shortly. May families and individuals aren't around during the day and might get by with day time charging. I had no problem keeping hot water much of the year when working 2nd shift manually turning on the water heater. I am a single guy and the water, even with cold inrush in winter would be hot enough for showers 2 days if sparse other uses off my 30 gallon tank.


    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.
  • Anawa
    Anawa Solar Expert Posts: 225 ✭✭✭
    Erik, I'm still contemplating DC vs AC, as well as, some of the issues you mentioned in prior post. Your thoughts on:
    1- Setting the controller aux relay to start on absorb, or float? Is the difference 60v vs. 50v+, or other considerations?
    2- If I'm running AC mini-splits simultaneously with the water heating load (which is reality), what kind of issues will I expect to encounter?

    Anawa
    Paul 
    in Georgia

    System 1: PV- 410w Evergreen, Mppt- Blue Sky Solar Boost, Batt - 225ah Deka AGM, 12v led house lighting,
    System 2: PV- 215w Kyocera, PWM - Morningstar PS30, Batt- 225ah Deka GC's, 12v led house lighting, Dankoff 12v water pump,
    System 3: PV- 1.5kw Kyocera, Grundfos 11 SQF well pump, 3000 gal above ground water storage, dom water & irrigation,
    System 4: PV- 6.1kw Kyocera, Mppt- Outback FM80-2ea, Inverter- Outback FX3648-2ea, Batt- 804ah GB traction, Grundfos BMQE booster pump 240v, Mitsibushi mini-splits 240v, 18k and 15k