PV Hot Water For Your Camp, Simply The Best
Efficient hot water at your camp using existing solar panels and charge controller. Does not
reduce charging capability. It only uses power that would be wasted. Uses previous, Wind Dump Load, 300W inverter board. Requires existing solar panels to be a 36V or 60V grid tie panel array. Board power should not exceed 15V and limited by a 6.2K resistor and zener. Source voltage should be less than 65V. See just prior for modifications. Higher voltages, just use TL494 board.
Diode isolates system from charging to prevent damage tp PWM controllers and tracking of MPPT.
Heating water any other way is just wrong! Do not connect heaters to batteries. Inefficient and the batteries will never charge properly. If using less than a 36V array, don't even think about heating water.
A capacitor bank is required to store energy as is done in any MPPT controller. Diode isolation must be included to prevent possible damage to an existing charge controller. Power consumption is small enough that a 6.2K 1W resistor and a 12-15V zener is sufficient to power board from a 60V array of grid tie panels. A precharge resistor keeps capacitor bank near full voltage while drawing very little current. Capacitor bank prevents arcing when temperature control contacts open. Difference between the switch contacts will always be less than 30V due to capacitor bank
preventing extreme voltage drop.
Suggest using a 4-6 gallon water unit for fastest water heating. Check out ECCOTEMP EM-4.0 and WAIWELA WM-6.0 as examples of wall mount units under $200. Having hot water at the sink is nice and likely enough for a shower. If there is enough power available, use a 9 gallon tank. Add extra insulation to any tank. Try to start off with 85F water in the morning.
(1) L1392 board, ebay -- Inverter Driver Board Power Module Drive 300W
See prior post for modification details
(10) 10,000-12,000uF 200V capacitor bank
(1) 12V to 15V 1W zener
(1) 35A diode Additional parallel diodes prefered.
(1) 50K pot
(1) 180K for 50V, 180K for 50V scaling resistor
(1) 1K ohm 3W resistor, precharge
(1) 2.2K ohm resistor
(1) 6.2K ohm 1W resistor