Friday, April 30, 2010

First Full Month of Solar

As April ends, I can now assess the results of our first full month of having solar power. Specifically, I was very interested to see if my projections for solar production were even close. If you remember, I wrote this blog entry back in October 2009 as I was trying to determine how big a system to get, what sort of output I could expect and what my savings would be. I created this Google Docs spreadsheet to help with all these calculations.

For the month of April, the spreadsheet predicted for the 3.68kW system we got, production of 513 kWH (this actually comes from the PVWatt tool mentioned in the spreadsheet). It didn't look like we'd get there as the 27th and 28th were overcast and rainy days, but the last 2 days of April turned in the highest production so far. Actual production came in at 538 kWH. Based on this, it looks like the analysis I did in the spreadsheet turned out very accurate and as a result, I'm very pleased with our purchase so far.

Monday, April 19, 2010

Dog Sitters: Don't Shortchange Customers With Automated Homes

We recently went on vacation for a few days and had a dog sitter/walker take care of our dog while we were gone. We had the sitter visit our dog during the day to walk, play with, feed and clean up after him. We chose the duration of the visits and were billed accordingly. To get to our dog, the sitter had to open the side gate, which of course, is monitored and logged by our system. I used that information to gauge when a visit started and when it ended. Our security cameras, which are recorded, could also provide an extra confirmation if needed.

Unfortunately, the results are not good. There was not a single visit where the sitter stayed for the duration we paid.

Visit #1: 18% short
Visit #2: 50% short!
Visit #3: 33% short
Visit #4: 26% short
Visit #5: 23% short
Visit #6: 28% short

Overall, we were billed for 28% more than the actual number of minutes. My wife and I were stunned by how the sitter consistently shortchanged our pooch and not just by a couple minutes. For example, a 30 minute visit was really only 15 minutes and a 1 hour visit was cut short by 20 minutes. All those 5 star reviews on Yelp must have been written by friends or completely clueless people (AKA normal people without automation systems).

Our dog is a very important part of our family, and it bothers us more that he was shortchanged on attention than us being ripped off. Needless to say, rather than confront the sitter, we are going to cut our losses and find a new service (and put up a review on Yelp). This brings up the question, is it really possible to find a sitter who actually stays for the agreed upon durations? You are really at the whim of the sitter's honesty and it seems really easy to cheat. How do you guarantee you get what you pay for?

Thursday, April 1, 2010

Overcast Day Has Greater Solar Intensity???

It seems counter-intuitive, yet on a cloudless, sunny day, our panels peaked at a lower electricity output than on a day with overcast. In fact, on the cloudy day, our panels maxed out the inverter, causing it to clip. See the graph below where I combined the charts of 2 different days.

The red line shows the nice production curve on a cloudless day, but the green line shows the output on a cloudy day. The green line maxed out earlier in the day and even later in the day than the red line.

The sunlight hitting earth must be reflecting back up to the sky, but the overcast is causing it to reflect back down again. This results in more solar energy hitting the panels. I would assume that the glass over the panels is like this as well - allowing the sunlight to pass, and some light that reflects off the panels would get reflected back to the panels by the glass.