Follow Up: Bob's Solar Project
A few weeks ago we wrote about Bob's Solar Project, a blog about an individual's do-it-yourself project of installing solar panels on his house. Back then, the installation wasn't completed, so a few questions were left hanging up in the air, but now that things have progressed past the installation point, lets see how they turned out: "The good news is that all 84 shingles are connected and putting out power--lots of it. At one point on Friday, the charge controller registered over 1700 watts of solar power coming from the roof! That's over 20 watts per shingle. They're rated at 17 watts, although Unisolar says to expect higher power in the first month or two of operation."I was even getting several hundred watts during cloudy or daylight conditions when the sun wasn't shining on the roof (this time of year, the sun actually rises well north of east and sets north of west). The total power recorded by the charge controller yesterday was 8.3 kilowatt-hours--more than I use most days. It could have been substantially more, except that the power stops once the batteries are charged and nothing is running. I did everything I could to use that power--laundry, dishwasher, vacuum, and run the dehumidifier--but I still couldn't use all of the sun power available.
Which leads to the bad news. My batteries [which were bought second hand to save money] appear to be pretty bad. They were probably bad when I bought them, although overcharging them the first day the system was hooked up probably didn't help (although they shouldn't have overcharged so quickly if they were good). Basically, they have extremely limited capacity. [...] So new batteries are now on the agenda. [...] I'll probably go with 8 Rolls-Surrette S-460 batteries, giving me 460 amp-hour capacity, or around two to three days of normal use without sun.
More on the blog.