Solar Power Devices

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I still haven't found my Tmp102 sensor, but I did find a DHT22 (RHT03) temperature and humidity sensor that uses a single-wire interface.

 

DHT22

DHT22 temperature sensor

 

I don't think that I'll use this sensor in my final installation, but it will allow me to work through any issues with my 8266 program.  I've found that the 18B20 temperature sensor is available with a waterproof housing and a 2 meter cable, so I think I'll get that from Amazon.  Unfortunately, I lost a delivery from Amazon today.  USPS claimed to have delivered to my locked mailbox - hopefully I can find who they delivered it to.....

 

18B20

18B20 temperature sensor

 

The 18B20 also uses a single-wire interface, but it is the Dallas One-Wire which isn't code compatible with the DHT22.  Luckily there are libraries available so swapping should be quick.

 

Logging

My original plan was to log the temperature and irradiance data to Google sheets, but I'm having some problems getting the HTTPSRedirect library to work.  I'll need to work this out later, but since time is short I decided to fall back to initially logging to ThingSpeak.  I added the ThingSpeak library to the Arduino IDE and a new Solar SPEC channel to my ThingSpeak account.  I tested the logging and it's all working.

 

ThingSpeak channel

Thingspeak channel

 

Now I need to calibrate my irradiance readings with the Daystar meter.  To expedite the program I am currently just using a linear fit to about a dozen data points.

 

LiPo circuit:

I plugged in the LiPo battery and got that all charged up.  I am using a single cell 3.7V 1200mAh battery.  My original thought was that I could connect the solar cells to the VIN input on the 8266 Thing, but looking at the schematic realized that VIN is on the wrong side of the battery charging circuit.  To be able to power the 8266 and charge the battery, I'll need to connect at VUSB.  Think that I'll need to hack up a micro USB cable.

 

LiPo charger

 

And as genebren pointed out to me earlier - the LiPo charger is set up for fast charging @500mA via the 2K programming resistor.  I'll probably want to restrict that charging current to 100mA.  It appears that the 8266 Thing is averaging about 40mA including the WiFi bursts, so I'm probably okay until winter shows up.  I should put some power management in the program.

 

The Heat is On.....

My wife and I are taking a long 4-day weekend in Chicago, so it's going tough to get everything finished by the end of next week.