With the fantastic monitoring tools available today, we can see exactly how much energy production drops on cloudy days and when storms pass by. Tropical Storm Isaac just passed by Southwest Florida, and I’ve been reviewing energy output from many of the systems we have out there. Saturday and Sunday were completely cloud covered days. Sunday August 26, 2012 was not only cloudy, but it was dark and rainy virtually all day long.
Despite the cloud cover, photovoltaic systems continued to put out significant amounts of energy. In general, most systems across Southwest Florida had production cut in half on Saturday and lost almost 3/4ths production on Sunday. Here are a couple of examples:


The last two days were extraordinary, of course. It is interesting to see the performance of the systems during a storm, because there would definitely be an impact on battery backup systems if a power outage were to occur during a storm. Fortunately, there is usually plenty of sunshine to recharge batteries the day after a storm. We still have off and on rain today, but I have seen glimpses of blue sky already. Go Sun!