Author Topic: Power 48v heating elements directly with Kid?  (Read 114 times)

openplanet

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Power 48v heating elements directly with Kid?
« on: April 21, 2020, 11:33:08 PM »
A friend is planning to power the "48 volt d.c." 1200 Watt heating elements in his hot water tank with the Kid. (I put the quotes around 48 volts because it's a silly specification for a heating element; resistance makes far more sense.)   As this will be the only load, he asked me whether he can forgo a battery bank that would normally power the controller, and instead power it with a 48vdc power supply, run off his grid connection.  I said....that's an interesting question.  I'll run it by the brilliant folks who frequent the Midnite Solar Forum!

Thx
« Last Edit: April 21, 2020, 11:40:59 PM by openplanet »
_____________________________________
The Sun is but a morning star.  --  H.D.Thoreau
https://www.youtube.com/watch?v=cIANk7zQ05w

Two 1.5 kW arrays --> two Classic 150s --> WbJr. --> four parallel 100 Ah/48 volt rack mount LiFePO4 --> Outback FXR3048 inverter.

ClassicCrazy

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Re: Power 48v heating elements directly with Kid?
« Reply #1 on: April 22, 2020, 01:39:11 AM »
If your friend has grid power why not put a regular heating element in and just run the heater off of that ? 
Does he have a 1500 watt 48v power supply ?
What he wants to do doesn't make any sense because it would be more efficient to replace the heating element and run it off either 120v or 240 grid instead of heating up a power supply( 90 something % efficient )  and heating up the Kid ( 90 something % efficient ) to run 30 amps through it. You would be loosing power in the conversions.

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

openplanet

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Re: Power 48v heating elements directly with Kid?
« Reply #2 on: April 22, 2020, 11:43:44 PM »
He wants to test this kind of setup in anticipation of going fully off grid at another location.  If he has success with this arrangement, he will power the Kid with a very small 48 volt battery bank. 
Not sure why you asked about a 1500 watt 48 volt power supply.  The power supply would only need to power the controller itself.
_____________________________________
The Sun is but a morning star.  --  H.D.Thoreau
https://www.youtube.com/watch?v=cIANk7zQ05w

Two 1.5 kW arrays --> two Classic 150s --> WbJr. --> four parallel 100 Ah/48 volt rack mount LiFePO4 --> Outback FXR3048 inverter.

ClassicCrazy

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Re: Power 48v heating elements directly with Kid?
« Reply #3 on: April 23, 2020, 12:26:02 AM »
okay that is what I was wondering about.
If someone wants to direct heat water from PV you don't need a controller at all. You just connect the PV directly to the heating elements. You need something like SSR to turn off the power to the heating elements to keep the water from over heating but that is it. There would be no other conversion of power required. The trick is to try and match the resistance of the heating elements to the maximum power of the PV panels.
If you do what is suggested and use the Kid controller you loose energy because of the inefficiency of controller converting the power.
This winter I hooked up a PV direct to water heating element and it works.
Here is some info on direct PV water heating .
http://waterheatertimer.org/Photovoltaic-water-heater.html

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