In the past few months I was forced to slow down a little due to the arrival of Christmas, the New Year, house painting, home Spring cleaning, and, last week, the Lunar New Year celebrations. The weather also compounded the slow down with temperatures dropping to +5 Celsius which is cool for Hong Kong.
The weather this morning is around + 13 Celsius and I am about commence making up a sun follower circuit that may well end up with forumite Sparweb.
Notice the use of the words sun follower rather than sun tracker because the former is a more correct description.
Let me assure readers that I do not have a perfect sun follower circuit and it has limitations which make it less than perfect. These limitations are quite simply “clouds.†Any light based sun follower/tracker circuit which works from LED's, LDR's, Infra-red, or equivalent light based components will always be at the mercy of clouds interrupting the way the system works.
For those who want ‘perfect' sun following electronic circuits the only way to go is with programmable logic using a real time clock. Sun following by this method is almost guaranteed irrespective of rain, clouds, snow, typhoons, water spouts and anything else nature can supply.
Today I shall start with an experiment to upgrade my sensor unit so that two LDR's (East and West) can be housed in one weatherproof box rather than two. Initial testing this will take about five minutes and then I shall place it on my own photo-voltaic assembly for testing over a few days. I am optimistic that this experiment will be successful, and, if so, it will lead to a substantial reduction in hardware and construction time.
For those interested in how my system performs in different weather conditions I hope the following one-line descriptions will be adequate:-
Pure blue sky, no clouds all day – system works perfectly from sunrise to sunset. Cannot be faulted.
Dark morning with thick heavy grey cloud – moves to the noonday position and stays there all day until light fades and it parks in the East.
Overcast morning, full cloud cover, but looks as if the sun may come out later - moves to the noonday position and stays there all day until light fades and it parks in the East.
Overcast in the early morning and the sun appears – the system may track a short way at first, and as the sun power increases it will track in the required way all day.
Sunrise for a nice day and the system will follow as required, but then thunder clouds arrive at midday and the sky become so black that the street lights turn on. The system will stop tracking and park in the East.
These are just some on my observed examples and I suspect that other forumites using similar circuits will have similar stories to tell.
The thing I like about this circuit is that it only ‘tracks' from East to West. It is not like other well known circuits that track for the brightest spot in the sky and, depending on winds and clouds, can result in an actuator whirring endlessly hunting for the ‘brightest' spot.
I shall do my best to upload a photograph of the latest – all in one - sensor box with early comments in the next few days.
Spring is on the way!
David in Hong Kong.
