Solar Power and The Raspberry Pi/Arduino New Results

The new additional solar panels have now been installed for a few days on the Project Curacao box.

The ideas was to increase the power to the Arduino by about 50% and the power to the Raspberry Pi about 25%.  There was one panel on the Arduino BatteryWatchdog previously.  Why does it not increase the power by 100%?  It is because I changed the angle of the panels to the sun. Looking at the result, we should go up by about 50%.

The Arduino should be much more reliable now that we have added a WatchDog board.

Arduino and about 25% for the Pi. So far the results look about right.  The full system is shown on the right.  You can see the box, the old solar panels (new ones on top) and the WeatherRack in the background (as well as the wind power turbine – more on that as we get data from the new system).

 First Days of Data

I use my excellent control panels (built using RasPiConnect on my iPad) to see the performance of the new panels.  RasPiConnect allows you to put graphs, meters, charts and photos on your iPad / iPhone without any iPad / iPhone programming.

The first two days of solar power on the Raspberry Pi is below:

Lots of current being generated.  The voltage curves look like this:

Note that the solar power voltages are going about 5V.  This means that the batteries are fully charged.  Good news, considering the days have been partly cloudy.

The Arduino Battery Watchdog is also showing higher than 5V.  That battery is being fully charged as well.

Finally, no posting about Project Curacao is complete without a new picture from the Box.

Angle to The Sun

Angle to the sun is very important.  The difference between 12 degrees (pointed at the sun) and 90 degrees (flat on such in this picture) is about 50%.  At this time of year the maximum energy flux on the panels over a 24 hour period from the sun will be when the panels are pointed straight at the sun when it crosses the meridian about noon. That’s pretty much straight overhead at 12 degrees latitude at this time of year. With the camera
pointed at the ocean the box is about 15-20 degrees from vertical the flux will be (sin x)*flux (max), where x is the angle (angle(max)-angle(box)), certainly less than half of what it gets if pointed straight up.

Upgrades

Below you can see the two more solar panels on the top of the Box, to give the system some extra margin.

I want the Battery Watchdog to run 24/7 and I found in the case of a cloudy week, the Arduino would run out of power and quit.  I fixed this in three ways:

• Adding a Watchdog board (soon to be a SwitchDoc Labs product) to reset the Arduino if it goes down
• Adding a new solar panel that should add 70% more power to the system
• Replacing the flaky DS1307 RTC with a more reliable DS3231 RTC

This is the inside of the box showing the new Watchdog board, the WeatherArduino board (with the DS3231 RTC in the foreground attached to the WeatherArduino board).

 

The box is in it’s new holder.  The last problem with reading the power supply voltage on the Arduino turned out to be a wiring mistake.  I wired the current meter in the ground line instead of the power line, so it always read 0.0V.  Fixed!