Solar Switch for Water Heater

// This sketch is for Arduino Uno, with a clock, an LCD screen, a mini sloar panel, an infrared sensor and a relais
// Solar energy is measured by a mini solar panel attached to a window, If solar energy level exceeds a threshold voltage then a relais switches on an electric water heater.
// If by the end of the daylight the duration of the water heating is insufficient,(heating < 2 hours) then the water is further heated with main grid energy  
// The IR sensor switches on the light of the LCD display
// Design by Kees Vink
// This software is open source.
//Components:
// Mini solar panel: positive on Analogue in A0
// clock: SCL op Analog in A5, SDA op Analog in A4, VCC op +5V
// LCD display: like clock (parallel to clock, both feeding and I2C)
// Relais: S on pin 10
// 
//DS3231-AT24C32-IIC-High-Precision-Real-Time-Clock-Module-p-81066.html?akmClientCountry=NL&utm_design=41&utm_source=emarsys&utm_medium=Neworder171109&utm_campaign=trigger-emarsys&utm_content=winna&sc_src=email_2675773&sc_eh=5e919a3f442cad831&sc_llid=6449160&sc_lid=105229698&sc_uid=CdRKDGHiw9&cur_warehouse=CN
//IIC-I2C-2004-204-20-x-4-Character-LCD-Display-Module-Blue-p-908616.html?utm_design=41&utm_source=emarsys&utm_medium=Neworder171109&utm_campaign=trigger-emarsys&utm_content=winna&sc_src=email_2675773&sc_eh=5e919a3f442cad831&sc_llid=6449160&sc_lid=105229698&sc_uid=CdRKDGHiw9&cur_warehouse=UK
//UNO-R3-ATmega328P-Development-Board-For-No-Cable-p-964163.html?akmClientCountry=NL&utm_design=41&utm_source=emarsys&utm_medium=Neworder171109&utm_campaign=trigger-emarsys&utm_content=winna&sc_src=email_2675773&sc_eh=5e919a3f442cad831&sc_llid=6449160&sc_lid=105229698&sc_uid=CdRKDGHiw9&cur_warehouse=UK
//5V-PIR-Motion-Sensor-Adjustable-Time-Delay-Sensitive-Module-p-1244536.html?akmClientCountry=NL&utm_design=41&utm_source=emarsys&utm_medium=Neworder171109&utm_campaign=trigger-emarsys&utm_content=winna&sc_src=email_2675773&sc_eh=5e919a3f442cad831&sc_llid=15735979&sc_lid=105229698&sc_uid=CdRKDGHiw9&cur_warehouse=CN
//Portable-Mini-5V-60mA-0_3W-Solar-Epoxy-Panel-p-1144421.html?gmcCountry=NL&currency=EUR&createTmp=1&utm_source=googleshopping&utm_medium=cpc_bgcs&utm_content=frank&utm_campaign=pla-nlg-rm-all-purchase-pc&gclid=Cj0KCQiAr8bwBRD4ARIsAHa4YyK8nkgjRuT2EZHUMS5KNWzDH5LIH1HWJv7SQh2aNpPYdD7o40G5GuQaAgu1EALw_wcB&cur_warehouse=CN

#include <Wire.h>
#include <LiquidCrystal_I2C.h>
#define DS3231_I2C_ADDRESS 0x68
#include <SPI.h>
#include <DS3231.h>  
DS3231 Clock;
RTClib RTC;
byte Year;
byte Month;
byte Day;
byte DoW;
byte Hour;
byte Minute;
byte Second;

bool Century=false;
bool h12;
bool PM;
byte ADay, AHour, AMinute, ASecond, ABits;
bool ADy, A12h, Apm;
bool Daltarief,Boiler_on,grid_time_window;
int minontime = 300;  // minimal time (s) boiler_on before it will be turned off because of too low solar light to avoid too many swaps (pendelen)
long  lastswitchtime,lastIRtime;
float V_threshold=2.35;
long starttime,sumtime,diftime,ontime,onLighttime;
int pinOut = 10;
int nswitchtimes = 0;
int solarpin = 0;  // pin number of solar 
// IR sensor:
int sensor = 2;              // the pin that the sensor is atteched to
int state = LOW;             // by default, no motion detected
int val = 0;                 // variable to store the sensor status (value)

#define BACKLIGHT_PIN     13
LiquidCrystal_I2C lcd(0x27, 2,1,0,4,5,6,7,3, POSITIVE);  // Set the LCD I2C address

const uint8_t charBitmap[][8] = {
   { 0xc, 0x12, 0x12, 0xc, 0, 0, 0, 0 },
   { 0x6, 0x9, 0x9, 0x6, 0, 0, 0, 0 },
   { 0x0, 0x6, 0x9, 0x9, 0x6, 0, 0, 0x0 },
   { 0x0, 0xc, 0x12, 0x12, 0xc, 0, 0, 0x0 },
   { 0x0, 0x0, 0xc, 0x12, 0x12, 0xc, 0, 0x0 },
   { 0x0, 0x0, 0x6, 0x9, 0x9, 0x6, 0, 0x0 },
   { 0x0, 0x0, 0x0, 0x6, 0x9, 0x9, 0x6, 0x0 },
   { 0x0, 0x0, 0x0, 0xc, 0x12, 0x12, 0xc, 0x0 }

};
// Convert normal decimal numbers to binary coded decimal
byte decToBcd(byte val){
  return( (val/10*16) + (val%10) );
}
// Convert binary coded decimal to normal decimal numbers---------------------------------------------------------------------------------
byte bcdToDec(byte val){
  return( (val/16*10) + (val%16) );
}
//-----------------------------------------------------------------------------------------------------------------------------------
void readDS3231time(byte *second,
byte *minute,
byte *hour,
byte *dayOfWeek,
byte *dayOfMonth,
byte *month,
byte *year){
  Wire.beginTransmission(DS3231_I2C_ADDRESS);
  Wire.write(0); // set DS3231 register pointer to 00h
  Wire.endTransmission();
  Wire.requestFrom(DS3231_I2C_ADDRESS, 7);
  // request seven bytes of data from DS3231 starting from register 00h
  *second = bcdToDec(Wire.read() & 0x7f);
  *minute = bcdToDec(Wire.read());
  *hour = bcdToDec(Wire.read() & 0x3f);
  *dayOfWeek = bcdToDec(Wire.read());
  *dayOfMonth = bcdToDec(Wire.read());
  *month = bcdToDec(Wire.read());
  *year = bcdToDec(Wire.read());
}
//-----------------------------------------------------------------------------------------------------------------------------------
void displayTime(){
  byte second, minute, hour, dayOfWeek, dayOfMonth, month, year;
  // retrieve data from DS3231
  readDS3231time(&second, &minute, &hour, &dayOfWeek, &dayOfMonth, &month,
  &year);
  // send it to the serial monitor
  lcd.setCursor (0 ,0 );
  lcd.print(dayOfMonth, DEC);
  lcd.print("/");
  lcd.print(month, DEC);
  lcd.print("/");
  lcd.print(year, DEC);
  lcd.print(" ");    
  lcd.print(hour, DEC);
  if (hour == 0){
    sumtime = 0.;
    nswitchtimes = 0;  }  
  // convert the byte variable to a decimal number when displayed
  lcd.print(":");
  if (minute<10){
    lcd.print("0");
  }
  lcd.print(minute, DEC);
  lcd.print(":");
  if (second<10){
    lcd.print("0");
  }
  lcd.print(second, DEC);
  lcd.setCursor (0 ,1 );  
//  lcd.print(" Day of week: ");

  if ((hour>17) and (hour<20)) {        //opwarmen op netstroom  supplementair
    grid_time_window=true;}
  else{
    grid_time_window=false;}
  Daltarief=false;
  if (hour>22){
    Daltarief=true;}
  if (hour<7){
    Daltarief=true;}
  //lcd.print("hour:");
  //lcd.print(hour,DEC);
  switch(dayOfWeek){
  case 1:
    lcd.print("Sunday");
    Daltarief=true;
    break;
  case 2:
    lcd.print("Monday");
    break;
  case 3:
    lcd.print("Tuesday");
    break;
  case 4:
    lcd.print("Wednesday");
    break;
  case 5:
    lcd.print("Thursday");
    break;
  case 6:
    lcd.print("Friday");
    break;
  case 7:
    lcd.print("Saturday");
    Daltarief=true;    
    break;
    
  }
}
//-----------------------------------------------------------------------------------------------------------------------------------
void setup()
{   
  Wire.begin();
  Serial.begin(9600);  
  pinMode(10, OUTPUT);
   int charBitmapSize = (sizeof(charBitmap ) / sizeof (charBitmap[0]));

  // Switch on the backlight
  pinMode ( BACKLIGHT_PIN, OUTPUT );
  digitalWrite ( BACKLIGHT_PIN, HIGH );

  lcd.begin(19,4);               // initialize the lcd
  //pinMode(led, OUTPUT);      // initalize LED as an output
  pinMode(sensor, INPUT);    // initialize IR sensor as an input
 
  delay ( 1000 );
  
}
//-----------------------------------------------------------------------------------------------------------------------------------
void loop()
{  
   val = digitalRead(sensor);   // read sensor value
  if (val == HIGH) {           // check if the sensor is HIGH
    delay(100);                // delay 100 milliseconds 
    if (state == LOW) {
      DateTime now = RTC.now();
      lastIRtime = now.unixtime();
      lcd.backlight();  // set lcd light on
      state = HIGH;       // update variable state to HIGH
    }
  } 
  else {
      delay(200);             // delay 200 milliseconds 
      
      if (state == HIGH){
        state = LOW;       // update variable state to LOW
    }
  }
    
  int solarvalue = analogRead(solarpin);
  float solarvoltage = solarvalue*5.0/1024.0; //between 0 and 5 volts into integer values between 0 and 1023.
  
  lcd.home ();                   // go home
  lcd.clear ();
  displayTime(); // display the real-time clock data on the Serial Monitor // set dal/piek en timewindow grid charge
  lcd.setCursor ( 0, 2 );
  if (grid_time_window)
   { lcd.print("Tijdraam Grid");}
  else
    {lcd.print("Tijdraam Solar");    }
  
  lcd.setCursor ( 0, 3 );        // go to the next line  lcd.setCursor(col, row)  
  if (Daltarief){
    lcd.print("Low  tariff");}
  else{
    lcd.print("Normal tariff");  }
  
  delay(5000); // every second
  lcd.home ();                   // go home
  lcd.clear ();
  lcd.setCursor ( 0, 0 );        // go to the next line  lcd.setCursor(col, row)
  if (solarvoltage>V_threshold) 
    lcd.print ("Sunlight sufficient");
  else
    lcd.print ("Sunlight insufficient");  
  DateTime now = RTC.now();
  diftime = (now.unixtime()-starttime);
  ontime = now.unixtime()-lastswitchtime;
  onLighttime = now.unixtime()-lastIRtime;
  if(float(onLighttime/60)>1.)  // after 1 minute light out
    lcd.noBacklight();
  if ((grid_time_window) and (!Boiler_on) and ((float(sumtime/3600.)<2.))){  
    digitalWrite(pinOut, HIGH);  // switch the heater on
    Boiler_on = true;
    DateTime now = RTC.now();
    starttime=now.unixtime();
    lastswitchtime=starttime;       
    nswitchtimes=nswitchtimes+1;
    }
   
  if (!grid_time_window){
    if((ontime>minontime) and (Boiler_on) and (solarvoltage<V_threshold)){   // Boiler is on and will be turned off  provided it has been on for longer than minontime (to avoid oscillation/pendelen in time of 5 min.)
        digitalWrite(pinOut, LOW);
        Boiler_on = false;
        sumtime=sumtime+diftime;
        nswitchtimes=nswitchtimes+1;}
    else
      if(Boiler_on){
        sumtime=sumtime+diftime;      
        starttime=now.unixtime();
        }
    if((!Boiler_on)and(solarvoltage>=V_threshold)){   // Boiler was off and is now set on
      digitalWrite(pinOut, HIGH);
      Boiler_on = true;
      DateTime now = RTC.now();
      starttime=now.unixtime();
      lastswitchtime=starttime;       
      nswitchtimes=nswitchtimes+1;
       }}
  lcd.setCursor (0 ,1 );        // go to the next line     
  if(Boiler_on)  
    lcd.print ("Boiler aan");           
  else
    lcd.print ("Boiler uit");               
  lcd.print (" Nsw: ");
  lcd.print (nswitchtimes);    
  lcd.setCursor (0 ,2 );        // go to the next line        
  lcd.print ("Laadduur dag: ");
  lcd.print (float(sumtime/3600.));
  //lcd.print (sumtime);
  lcd.print (" u");
  lcd.setCursor (0 ,3 );        // go to the next line
  lcd.print ("V: ");
  lcd.print (solarvoltage);
  lcd.print (" Vt: ");
  lcd.print (V_threshold);
  delay ( 5000 );

}