A Forum run by Enthusiasts of MidNite Solar

Charge Controllers and Clippers => The "KID" charge controller => Topic started by: openplanet on April 21, 2020, 11:33:08 PM

Title: Power 48v heating elements directly with Kid?
Post by: openplanet 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
Title: Re: Power 48v heating elements directly with Kid?
Post by: ClassicCrazy 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
Title: Re: Power 48v heating elements directly with Kid?
Post by: openplanet 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.
Title: Re: Power 48v heating elements directly with Kid?
Post by: ClassicCrazy 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