DIY Chatroom Home Improvement Forum

DIY Chatroom Home Improvement Forum (http://www.diychatroom.com/)
-   Green Home Improvement (http://www.diychatroom.com/f97/)
-   -   PV Solar electricity tied directly to a DC Water Heater (http://www.diychatroom.com/f97/pv-solar-electricity-tied-directly-dc-water-heater-158982/)

JStofik 10-04-2012 06:14 PM

PV Solar electricity tied directly to a DC Water Heater
 
There are DC heater elements available for use in electric water heaters. Therefore, can PV Solar panel output (DC) be directly wired to a DC Water Heater of the matching voltage (assuming a thermal controller is installed to prevent over heating). Any ideas or brain storming?

Thanks,
Joe

Missouri Bound 10-04-2012 08:41 PM

Why not? What heats the water when it's cloudy?:eek:

JStofik 10-05-2012 09:15 AM

On cloudy days, the existing gas hot water heater will supply hot water. It will be plumbed so the DC electric is a feed tank to the existing gas water heater.

Missouri Bound 10-05-2012 09:24 AM

Got it!:thumbsup:

Thunder Chicken 11-09-2012 09:50 PM

You can do this, but energy-wise it is a waste of panel area. You would get more heat into the water using indirect solar thermal instead of PV.

You generally only get about 10% of your incident solar into the form of electricity in PV. Solar thermal is far more efficient if your goal is to make hot water.

Solarboy 08-23-2013 05:16 PM

There are some situations where a PV to thermal might be considered...the collectors are lighter and easier to anchor. Wire is easier to run than pipe, especially if you have a long and complicated pipe run. PV system doesn't need freeze protection. There should be some efficiency gain without an inverter, and no batteries or grid tie is needed.
But you are right, Thunder Chicken...last I checked, it took 5X's the money and 7X's the collector area for PV's to match thermal solar.

Oso954 08-24-2013 11:35 AM

Quote:

There should be some efficiency gain without an inverter, and no batteries or grid tie is needed.
Wiring PV directly to a heating element is not efficient. In fact, it may not work at all. The resistance of the heater will drive up the panel voltage. When you hit open circuit voltage, there will be no current flow.

You will need at minimum some type of heater controller, or a solar charge controller and a battery.

beenthere 08-24-2013 03:32 PM

Quote:

Originally Posted by Oso954 (Post 1233552)
Wiring PV directly to a heating element is not efficient. In fact, it may not work at all. The resistance of the heater will drive up the panel voltage. When you hit open circuit voltage, there will be no current flow.

You will need at minimum some type of heater controller, or a solar charge controller and a battery.

So 1 ohm of resistance is too much?

Solarboy 08-24-2013 08:37 PM

While PV is not my field (thermal solar is my thing) my gut instinct says that PV panels producing DC, into DC heating elements...without an inverter should be more efficient overall. I don't know "what it would take", but the fewer conversions the better, as a general rule. A charge controller and battery? Ok....so the PV's charge the battery and the battery runs the heater?

ehoez 08-27-2013 10:59 PM

any links?


All times are GMT -5. The time now is 09:20 AM.


Copyright 2003-2014 Escalate Media LP. All Rights Reserved