Does any one out there in cyberspace have any experience/advice about using a dual voltage 12vdc and 115vac water heater element for their onboard heater? Some background. I am installing 2 115 watt solar panels with two victron MPPT 75 15 smart controllers. Each panel goes to each controller, operating independently of each other. Each controller has a load output that can be programmed via bluetooth. According to Victron the load can be a water heater element. Basically, once the batteries (four T105 trojans deep cycle wired in series parallel for 450 amps) are charged the control output shifts from the batteries to the load output hopefully heating the water. There is also a 100 watt panel on the dodger goes to a gensun mppt controller that goes directly to the trojans and to the start battery via an ACR. The load output voltages (cut in and cut out) will have to be programmed in consultation with Rolls Battery company. The heater element will be powered from the excess power from the solar panels, not the batteries. Apologies for the long background for a simple question, however I am trying to foresee any reasonable basic questions that might be asked. Thanks to all and I look forward to a good discussion.
dual voltage water heater element
- Thread starter east coaster
- Start date
Your plan could work, but won't be very efficient with the size panels you have. The typical 6 gallon HW tank element is ~1400w @120vac. At best you'll be putting in 230w at 12vdc. The heating element won't get very warm, as it will only be receiving about 16% of the energy required to heat the element
Your thinking about this in a linear form.
With the solar panel as the center the batteries and the solar panel work together to provide power to the water heater "WH".
Solar panels supply power to the batteries. As you need heated water with the WH connected to the battery, the Batteries give up power to the WH. Should the load demand from the WH be less than the output of the panel then the panel sends power to the WH and to the batteries till full. At this point if WH is not needed the controler shuts the solar charger down. If the WH demands more than the panel then the panel and the battery work to meet the WH load.
This is accurate if the water heater is connected to the load bus for the batteries. The OP specifically stated the batteries are not connected to the HW tank thus, the OP is correct in his thinking and planning, except about the amount of energy being produces would have any noticeable effect on the water temp in the HW tank.
While I doubt this would work out powerwise, Tempco would be a good source for heating elements. They're selection is huge and is used extensively in the temperature control industry
I apologize for my delayed response to your replies. An out of town family health issue intervened and required rather immediate medical attention. That situation is stabilized for now. To the matter at hand, both victron and rolls battery contacted in separate emails and phone calls agree that it can be done. However it's not an effective use of my resources to heat the water adequately, therefore I am dropping this part of the project. I thank the respondents for their advice and sharing their experiences to my query. These forums continue to be a wealth of information and pragmatic advice based on the diverse and eclectic nature of all of its experienced members, again thank you.
