Coffee Space

Solar Panel

Specifications:

• 18V (in reality it actually seems to be lower than this - depending on light conditions)
• 2.5W
• 19.5 x 12 x 0.3 cm

Implementation:

0001  ________
0002 |        |     ____
0003 |  SP   +|----| WM |
0004 |       -|----|____|
0005 |________|

• SP - Solar panel
• WM - WeMos

Experience:

• Connects fine with large solder pads.
• Voltage is high enough in decent levels of sunlight (>10V).

Voltage Regulator

Specifications:

• 6-20V input
• 5V output
• 2A current

Implementation:

0006  ________
0007 |        |     ____      ____
0008 |  SP   +|----| VR |----| WM |
0009 |       -|----|____|----|____|
0010 |________|

• SP - Solar panel
• VR - Voltage regulator
• WM - WeMos

Experience:

• Too inefficient to be used on a solar panel of this size.

WeMos D1 R2

Specifications:

• >15mA current usage
• 5V (USB) or 9-24V (power jack)

Implementation:

0011 #include <ESP8266WiFi.h>
0012 extern "C"{
0013   #include "user_interface.h"
0014 }
0015 
0016 const char* ssid = "WIFI_NAME_HERE";
0017 const char* password = "PASSWORD_HERE";
0018 
0019 unsigned long startTime;
0020 WiFiServer server(80);
0021 
0022 #define TRUE 1
0023 #define FALSE 0
0024 #define DEBUG TRUE
0025 
0026 void setup(){
0027   /* Store data about starting conditions */
0028   startTime = millis();
0029   /* Begin the serial communications */
0030   #if DEBUG == TRUE
0031     Serial.begin(115200);
0032     Serial.println("There is life");
0033     delay(10);
0034   #endif
0035   /* Turn off WiFi LED */
0036   wifi_status_led_uninstall();
0037   /* Stop the WiFi completely dying */
0038   wifi_set_sleep_type(LIGHT_SLEEP_T);
0039   /* Start the Wifi connection */
0040   WiFi.begin(ssid, password);
0041   /* Wait until the WiFi is up */
0042   while(WiFi.status() != WL_CONNECTED){
0043     delay(500);
0044     /* Display attempt to connect */
0045     #if DEBUG == TRUE
0046       Serial.println("Connecting...");
0047     #endif
0048   }
0049   /* Begin the server on the WiFi */
0050   server.begin();
0051   /* Display local IP address */
0052   #if DEBUG == TRUE
0053     Serial.println(WiFi.localIP());
0054   #endif
0055 }
0056 
0057 void loop(){
0058   /* Wait until we find a client */
0059   WiFiClient client = server.available();
0060   /* Make sure we have a valid client */
0061   if(!client){
0062     return;
0063   }
0064   /* Wait until the client is available */
0065   while(!client.available()){
0066     delay(1);
0067   }
0068   /* Get all data from client */
0069   client.flush();
0070   /* Write the page */
0071   String s = "";
0072   s += "HTTP/1.1 200 OK";
0073   s += "\r\n";
0074   s += "Content-Type: text/html";
0075   s += "\r\n";
0076   s += "\r\n";
0077   s += "<h1>Data</h1>";
0078   s += " </br>status: alive";
0079   s += " </br>up_time_ms: ";
0080   s += (millis() - startTime);
0081   s += " </br>os_chip_id: ";
0082   s += system_get_chip_id();
0083   s += " </br>os_free_heap_size: ";
0084   s += system_get_free_heap_size();
0085   s += " </br>os_time_us: ";
0086   s += system_get_time();
0087   s += " </br>os_rtc_us: ";
0088   s += system_get_rtc_time();
0089   s += " </br>os_boot_time: ";
0090   s += system_get_boot_version();
0091   /* Output to client and then close */
0092   client.print(s);
0093   delay(1);
0094   client.stop();
0095 }

Experience:

• Lower power operations do not perform very well. The amount advertised do not match achievable values in reality. This could be for multiple reasons, but much more debugging is required.
• Solar panel was not able to provide enough power to get the WiFi started, despite the surface mount LEDs being activated.