The sun rises in the east, and sets in the west, in most places on this Earth. During our rotation, we present a different angle, at each moment. Early, the angle is acute, and the atmosphere blocks much of the available energy. At noon, of course, we reach peak output. From then, until the sun sets, the flow decreases. A cloud passing, can interfere with efficiancy.
There have been all sorts of Rube Goldberg devices to rotate panels to track the suns progress, return them to the morning poition, at dusk. But, the fact remains, that there is still a variation in the output.
I have built a number of passive homes, utilizing Trombe Wall techniques, and it's variations. It is a great way to get free heat.
I have been involved with hot water systems, since the 70's. They work, and make good bizness sense.
I do not believe the snake oil salesmen who talk about the short payback times for PV. There is too much maintainance, and loss, in the systems presently available.
Only with a massive array, could you have air conditioning, or pump water from a deep well, with PV, efficiently. I built an experimental house for some friends near Round Hill, VA. It's a weekend cabin, with both water and PV panels. They have lots of battery storage for now, because the panels generate for a week, or more, in between weekend visits. But, when they stayed for two weeks, during the winter, they ran short after four days, and had to cut back on some functionss, and use their gasoline generator to recharge the extra needed to keep the batteries.
I visit the former Solarex factory (now BP Solar), in Frederick, MD, from time to time, and have made friends with a couple of engineers there. I think I agree with them... it's too expensive yet, for general usage, and too limiting, yet, for most modern lifestyles!
Here's a place to find out about stand alone systems.
Here's a good approach to mainstreaming it...
