2.18 Summary and Final Tasks

So far, we have delved deep into the world of angles, time, and shading. Why have we done this? The solar resource is all about timing and placement of the SECS relative to the Sun, and the use of angles as coordinates in time and place are fundamental building blocks to the solar expert. We now have computational tools that make the work of calculating details trivial, but one must always know what the foundations are underneath those tools.

Who knows, maybe you will be the next open software developer to create a simple solar tool for resource assessment. You now have the keys to access many of those computational tools. More to the point, these fundamentals are not shrouded in mystery, and you don't necessarily need to pay for software to get access to them!

Looking ahead, I can tell you that students in residence at Penn State have already found a solar systems design plugin for Trimble SketchUp called Skelion, which does shading analysis just like you performed, but on the fly inside of the SketchUp design software. Both are free to use, and I'd recommend you take a look at each in preparation for your end of semester design projects! This is an untapped resource for you to explore, now that you know "how" the shading calculations work.

Knowing these principles of angles and time also exposes us to the strengths and potential weaknesses of purely geometric relations in the solar resource. As we shall see in the next lesson, the role of the atmosphere and meteorology will tend to muck up our ideal angles of beams of light, and produce anisotropic (uneven) intensities of irradiance over the day, which will of course influence our solar resource estimations.

On to the next lesson--let's learn about the role of weather and the sky dome in estimating the solar resource!

The Goal of Solar Design and our Three New Mechanisms

The Goal of Solar Design is to:

1. Maximize the solar utility
2. for the client
3. in a given locale.

Given the goal of solar design, we have learned of three mechanisms to leverage during the design process that will increase the solar utility for our client in their locale of interest:

1. Reduce the cosine projection effect on an aperture/receiver (the extreme angles of incidence, $\theta$ or low glancing angles $\alpha$),
2. Reduce the angle of incidence on an aperture/receiver (refinement on minimizing $\theta$),
3. Reduce losses from shadowing on an aperture/receiver.

In order to leverage these three tools, we have demonstrated that one needs to know where and when the Sun will be relative to our collector system.