Project: Solar/Wind PIC controlled battery array

Thread Starter

nsaspook

Joined Aug 27, 2009
13,080
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Shop power without solar load sharing. (the servers have dual power supplies) One can be on the utility while the other can be on backup or solar power.
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Solar load sharing limited to ~300W because of the current solar panel capacity. I have a 4000W 24VDC inverter on order.

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Max power sharing with the current inverter but it won't run for too long pulling battery power to make up the difference from the panels.
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~6A is being supplied by the battery to the inverter @ ~600W.
 

Thread Starter

nsaspook

Joined Aug 27, 2009
13,080
I'm using the original 24VDC inverter prototype system as a excess power dump load for for the FM80 solar energy bank. AC power from the main 4000W inverter system is used to keep that buffer battery bank charged and to power the 600W inverter that's switched to computer server power duty from online or stored solar. It all works by reading data from FM80 monitor system while using my Home Assistant automation server to control things with I/O data triggers to Matter AC sockets. One thing extra that was needed was a way to tell when the dump load system battery is fully recharged after a power run.
I designed and built a MODBUS master to query the dump load systems Renogy charge controller for an earlier version of a PV system monitor.
https://forum.allaboutcircuits.com/...c-controlled-battery-array.32879/post-1488589

So all I needed was to modify that to alert the HA system to shutdown the chargers power when the charge controller entered battery FLOAT mode. I already had some cheap WiFI door/windows alarm sensors for non-critical home monitoring.
Open one up to see the sensor was an old school mag reed switch.
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So all I needed was a open-drain output from the PIC18F1320 to simulate the magnet by shorting the transistor across the reed switch 2.5 volt pull-up to the wireless module input.
C:
if (c_crc == c_crc_rec) {
                        if ((temp = cc_buffer[4])) {
                            set_led_blink(temp);
                            switch (temp) { // check charge controller mode codes
                            case 1:
                                volts = CC_ACT;
                                FLOAT = true; //true means the WiFI read switch connection is open
                                break;
                            case 2:
                                volts = CC_MPPT;
                                FLOAT = true;
                                break;
                            case 3:
                                volts = CC_EQUAL;
                                FLOAT = true;
                                break;
                            case 4:
                                volts = CC_BOOST;
                                FLOAT = true;
                                break;
                            case 5:
                                volts = CC_FLOAT;
                                FLOAT = false; // open-drain pulls sensor voltage low, reed switch connections is shorted
                                break;
                            case 6:
                                volts = CC_LIMIT;
                                FLOAT = true;
                                break;
                            default:
                                volts = CC_ACT;
                                FLOAT = true;
                                break;
                            }
                        } else {
                            set_led_blink(BON);
                            volts = CC_DEACT;
                            FLOAT = true;
                        }
                    } else {
                        crc_error++;
                        set_led_blink(BOFF);
                    }
I registered on the IoT site of the CBU retailer to get a reference design of the door sensor to verify the connection point circuit.
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It's a pretty nice module.
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Two wires from the reed switch connected to the modbus controller RA4 open-drain output pin.
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The WiFI switch was sending "low" because of power usage, After the AC load was switched off the HA software switched it to recharge for a few hours, when the CC modbus master reads 'FLOAT' from the charge controller, that triggers the WiFI switch to 'normal' on the HA, HA turns off the charger. (The CC goes to idle, causing the 'low' signal again but no AC power loads are on, so the dump load system is idle)
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