PV Hot Water Controller Build From Inverter Board part 6 

This project is for those with some soldering skills and a real understanding of solar. It can be accomplished by anyone with motivation and the patience to learn. Order a minimum of two boards. You can not even replace the IC for the price of a second board. Have one to make mistakes with. Build a second board to have one as a spare. Boards from China change and become unavailable. ALWAYS READ ALL COMMENTS. They include information that may have been left out of the video or changes. MINIMUM MODIFICATIONS FOR ARRAY VOLTAGE LESS THAN 50V Cut traces at both power pins. Connect a minimum of two wires to the center common of the board for negative high current connection to the capacitor bank negative. DO NOT USE the negative screw terminal as the high current path. Jumper the two large traces together on the single FET used as ideal diode. Remove resistor at the end of the IC that goes from pin 16 to pin 2. Place that resistor on underside of board from pin 16 to pin 1. Lift resistor lead at pin 2 side. The other end of the resistor goes to common and remains. Lift resistor lead that goes from common to pin 1. The side that goes to common is lifted. Connect the two extened leads together. There should now be a resistance of 4K from common minus to pin 1. Remove soft start 1uF capacitor from pin 8 at the end of IC. Solder 1 uF capacitor to underside of two terminal connector. Banded side of capacitor to the negative. Solder the other end of capacitor to adjacent terminal. This is the pot input. Solder wire from pot input to pin 1. That pin goes to an easy large pad eith capacitor and resistor. Lift 100 ohm resistor at side of pot from pin 5 to pin 7. This is the deadband control. Put 100 ohm resistor in series or replace with 200 ohm resistor. Add two 1N4007 diodes to the three terminal connector. Almost any general purpose diode will work. The unbanded side goes to the outside pins. The banded sides go to the center pin. Center pin is the PV positive. Add a compensation capacitor from from comp pin 9 to common. Pin 9mdoes not have a pad and you need to flatten the pin and solder to it. This is delicate soldering operation and will not have much strength. Use capacitor value from .001 to .0047 uF. Build a capacitor bank with at least 10 capacitors, more capacitors the better. Consumer grade capacitors are aonl good for abour 1A each. Minimum total value should be 4700uf. For low voltage it should be 10,000uf OPTION A Solder a resistor from the center pin of connector to the positive of the two 470uF electrolytics. The resistance varies depends on the array voltage. Usually from 1K to 1.5K. A resistor dropping supply has the highest immunity to lightning spikes. Series resistors inprove that even more and prevent flash over. Ordering a 200 ohm 1/4W resistor for deadband, Just put a number of these in series to reach the correct resistance and place them in heat shrink tubing. Solder a 13V zener diode across that electrolytic capacitor. Banded end goes to positive. OPTiON B Use an isolated switching power supply to supply 12V to the two electrolytic capacitors. The power supply shown is 12V 300ma 100-380V DC / 70-270. At as low as 20V it will work with small loads like 20ma. I use capacitors thru mounting holes to create a good termiination to wires. This is the beast low voltage capability that I have seen with any power supply. Suggest minimum of 40V. Other supplies may require modification.