I cleaned 24 Solar panels in 30 min. See before and after pictures, power gen.

I have Asphalt composition shingle roof on 1 story ranch home
slope probably 20% and easy to walk on.

I have a ladder for easy access. My detergent was generic household
dish washing detergent which is safe enough for hands.

Mop is also a $10 mop with changeable pad.

I use a trickle of water from the garden hose to rinse the panel, apply the detergent on the pad and wipe the panel, then rinse it off.

Panel before cleaning:

Panel after cleaning (about 30min for 24 panels)

Not exactly the same angle I guess. Next time I will use tripod.

2 days ago it was a completely clear sunny day like today. Panels were cleaned
between 10:30am and 11am. You can notice the difference in the next 2 pictures. Power generated was about 4% higher. Not bad for 30 min of my time.

Did you lose good tennis balls every time your were on the court? Have trouble tracking the use of your balls?

You are not alone. For years, I never figured out the way to keep track of the tennis balls.

I am really finicky about the quality of the bounce and the weight of the ball. In the past when I played with worn out balls, I ended up getting tennis elbow because I had to hit much harder. To make it complicated, the temperature and humidity does affect the bounce. Temperature more than humidity?

Here are a few interesting links
Approval Tests
The Effect of Temperature, Time, and Humidity on the Bounce of Tennis Balls
Does Temperature Affect How High a Tennis Ball Will Bounce?
The tennis ball bounce test
Does a tennis ball bounce higher in cold weather or warm weather?

So, a wise friend of mine named Kumar (last name concealed to protect the innocent:-)) suggested that sharpie can be used to mark the balls. That motivated me to look through my so called worn balls. I took the balls to my kitchen and dropped them to the kitchen floor one at a time using a new ball as a reference and then I saw how much the new ball bounced up. Then I sorted my Costco Penn Heavy Championship Heavy Duty balls used at least once by the numbers. BTW, number is just an identifier. No reference to the type of the ball. Out of 21 balls, I ended up picking up 18 as good. I took them to the court where 3 of us played today from 9:45am in Fremont, CA for 90 minutes where we rotated every 10 minutes. Temperature was about 70F on a totally clear sky.

After 90 minutes of play, we felt they still had a lot of good bounce left. We decided to mark the ball with 1 horizontal bar for every 1 hr of play for 2 peopel with 6 balls or 90 min of play with 3 people with 9 balls. These balls will get 2 horizontal bars because we used them at least once if not twice.

I did a "scientific" bounce test on 9 balls. They were all dropped 43" on to a laminate floor. The average bounce seems to be be about 50% or about 21 to 22".

I will repeat this test on the same balls after I use them for 90min with the same 3 people next week and see how much the degrade.

Here are the photos of marking the balls.

Here is how I measured the bounce.

Here is the video

 How I measured the bounce of tennis balls.

Just what do we mean by Internet of Things.

Internet first came to universities, then companies and their employees. Then came ISPs and it came to people. What that means is that devices like computers, smartphones, tablets people own connect to Internet.

Along with people came their "things" which they may not carry but wanted them to be visible or controllable from Internet.

This topic is too elaborate to make it a blog. I decided to put in a
PDF file.

Unlike my previous blogs, I asked for input from two of my close friends with the idea that this article may be something any one can make sense of rather than use a lot of techy jargon.

Feel free to ask questions or leave comments. I can add more articles on this topic based on that.