Author Topic: Yet another (Ughh) hot water question...  (Read 161 times)

openplanet

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Yet another (Ughh) hot water question...
« on: April 04, 2019, 12:17:26 AM »
I have two 2kw arrays and two Classics.  In the summer a single array+Classic is sufficient for battery charging.  So for summer I'd like to connect the other array+Classic directly to a hot water heater. 

1. Am I right that this will simplify the configuration (vs leaving both Classics connected to the battery bank)?
2. Can anyone point me to relevant forum posts?  I've hunted for info about this specific approach, without success.

Thanks, as always.

ClassicCrazy

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Re: Yet another (Ughh) hot water question...
« Reply #1 on: April 04, 2019, 12:33:40 AM »
You could hook the second array directly to the hot water heater element  but you will need to make a DC rated temperature control using a temperature control of some sort ( lots of inexpensive ones on ebay ) and you need to use a heat sinked DC solid state relay rated at sufficient voltage and amps to handle the PV current.

Larry
system one
Classic 150 , 5s4p  Kyocera 135watt , 12s Soneil 2v 540amp lead crystal for 24v pack , Outback 3524 inverter
system two
Classic 150 ,5s 135 watt Kyocero , 16s Calb 100AH LiFePO4 , Outback VFX 3648 inverter
system three
Midnite KID MPPT 24 DC in to  12 volt AGM batterie

ClassicCrazy

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Re: Yet another (Ughh) hot water question...
« Reply #2 on: April 04, 2019, 12:36:43 AM »
system one
Classic 150 , 5s4p  Kyocera 135watt , 12s Soneil 2v 540amp lead crystal for 24v pack , Outback 3524 inverter
system two
Classic 150 ,5s 135 watt Kyocero , 16s Calb 100AH LiFePO4 , Outback VFX 3648 inverter
system three
Midnite KID MPPT 24 DC in to  12 volt AGM batterie

openplanet

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Re: Yet another (Ughh) hot water question...
« Reply #3 on: April 05, 2019, 04:16:00 PM »
Thank you.

openplanet

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Re: Yet another (Ughh) hot water question...
« Reply #4 on: April 10, 2019, 07:23:41 PM »
Larry--Given that during the summer I don't need my second array for battery charging, is there any reason you can think of NOT to connect it directly to the water heater (w temp control and SSR) rather than involving my second Classic?
Another question: As we all know, PV arrays are not to be disconnected under load.  But in the scenario where the array goes to the hot water tank via a (temp controlled) SSR, doesn't the SSR opening amount to disconnecting the array "under load?"
Thank you.

ClassicCrazy

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Re: Yet another (Ughh) hot water question...
« Reply #5 on: April 10, 2019, 10:24:42 PM »
I think the only reason you don't disconnect the PV under load is because then you will get an arc across the contact points of the switch - or of the end of wires if you pull them apart. You can disconnect PV using DC rated breakers.  A solid state relay is not like a mechanical switch and a DC rated SSR is designed to disconnect DC loads.

I guess if you don't need the PV in summer to take care of your batteries properly there is no harm to run them to water heating instead.

Larry
« Last Edit: April 10, 2019, 10:28:45 PM by ClassicCrazy »
system one
Classic 150 , 5s4p  Kyocera 135watt , 12s Soneil 2v 540amp lead crystal for 24v pack , Outback 3524 inverter
system two
Classic 150 ,5s 135 watt Kyocero , 16s Calb 100AH LiFePO4 , Outback VFX 3648 inverter
system three
Midnite KID MPPT 24 DC in to  12 volt AGM batterie

Westbranch

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Re: Yet another (Ughh) hot water question...
« Reply #6 on: April 11, 2019, 05:29:21 PM »
how do you get hot water in the winter?
KID FW1811 560W >C&D 24V 900Ah AGM
CL150 29032 FW V.2126-NW2097-GP2133 175A E-Panel WBjr, 3Px4s 140W > 24V 900Ah AGM,
2 Cisco WRT54GL i/c DD-WRT Rtr, NetGr DS104Hub
Cotek ST1500 Inv  want a 24V  ROSIE Inverter
OmniCharge3024  Eu1/2/3000iGens
West Chilcotin 1680+W to come

OffGrid Wanabe

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Re: Yet another (Ughh) hot water question...
« Reply #7 on: April 15, 2019, 03:09:22 PM »
I used a Fotek SSR digital relay dc controlled to switch AC and left the Midnite hooked up to the array and used the Aux 1 in diversion mode to control the digital relay that way my batteries are always charged and I get hot water. I bought the biggest one I could find 80amps and only use 15 amp AC breaker on the 1500 watt 120 ac element but it makes hot water. I know the 80 amp digital is a fake so I oversized it also I have it on a large heat sink and in a metal electrical box I have monitored it for heat and the highest it has got is 90 Fahrenheit.
Good luck
« Last Edit: April 15, 2019, 03:19:35 PM by OffGrid Wanabe »