solar tracking

are you menaing equipment efficiency? or capability utilazation rate?

taking an advertise of the tracking system, the solar surface can capture sun lignt all the time. it has good capacity utlilzation rate.

but it cannt rise efficiency.

Yes, the collection of energy will be more if the collector is tracked.

But as others have already said, it is trade off between the added cost of tracking and additional energy captured.

But, here we an differentiate the tracking in two types of tracking:

1. Tracking over the day time, which needs motorised tracking

2. Seasonal tracking: The Sun moves by 47 deg over the year. For any location, normally the collected is fixed with its facing towards celestial equator to get best (possible) energy collection over the year. (Depending up on the needs this may be different, so that collection may be more in winter.. for Solar Thermal). Means the inclination set is degrees equivalent to the latitude of the location (Southwards for north hemisphere). But if we provide some hinge and go on changing the inclination every 15 days say, the energy collection will be much more. The inclination southwards you have to set is Latitude - Declination of Sun on cetral day of your dates of adjustment.

With this tracking, no much additional cost will there nor any maintenance expense, but you achive much more energy collection.

Self tracking designs are also worth looking at. If the collector is a long strip mounted as a cord to the sun's daily path during and the concentrator is a hyperbolic mirror with its center axis perpendicular to sun's average inclination and its focus on the "backward" facing collector, then most of the reflected / collected light will fall upon the collector no mater what the sun's particular position in the sky.

Since the incident energy on the collector strip will be many times higher than in a more typical installation calculate the maximum thermal load and electrical load on the collector so as not to thermally or electrically burn it out.

Best wishes,

Mr. Gee

It will increase the energy captured over the day.
It will loose out in capital expenditure, increased maintenance and decreased reliability.

It is a trade off between those factors...are you talking photovoltaic or solar-thermal? If it's a domestic solar water heating system the added complexity would probably no be worth the trouble...although passive or solar tracking reflectors could be a good thing.

My watchword for any engineering is simplicity.

Del

It pays off for very large systems, the energy capture is slightly better, but the big benefit is in being able to maximize the available productive land area. Fixed systems with multiple arrays have what are called "shadow losses" if you get the arrays too close to each other, so you lose effective area efficiency. Tracking lets you maximize the exposure when the arrays are packed closer together without casting shadows on each other, increasing the net power yield per hectare.

By the way, the power required to track is not that much, the movements don't need to be continuous.

But if it is one or even a few arrays on your roof, the net yield increase is not likely worth it.

Hello Louwel,

Try this thread http://cr4.globalspec.com/thread/23887#newcomments

#33 will eventualy take you here http://www.redrok.com/electron.htm#led3x

Brad

Besides efficiency, this is a present worth (or life cycle) question. Will a tracked system produce enough extra energy to make it worthwhile installing and maintaining the tracking equipment?

Obviously the area seen by the solar rays is smaller as the panel (Solar Electric) becomes oblique to the rays but apart from that smaller area, do the cristals output less if the radiation is not at 90º? I want to make my 900watt array track when time is available.

do the cristals output less if the radiation is not at 90º?

Hello capblanc,

I can't say for the crystals of the solar panel, but at certain angles, far from 90 deg., the glass becomes clear or reaches maximum transmission of the light. Laser tubes sometimes have oblique angled flat lenses to minimize out put losses.

So then it comes down to conversion losses over the spectrum of absorption. That could be different for each type of doping for the crystals. And different types of cover glass would have different angles of maximum transmission per wave length.

Could be an area of improvement.

Brad

Hi Brad,

Your remark about glass transmissivity being higher at angles if incidence less than 90º doesn't make sense to me on two scores.

1. The more acute the angle of incidence the greater the apparent thickness of glass and
2. The more acute the angle of incidence the greater will be the reflection.

The question I was asking was does anybody know how the angle of incidence affects the crystal output. That is;- 90º +/- 10º will make no appreciable difference to the apparent area presented to the Sun nor will the losses mentioned above be different at those angles but if the crystals are directional then that would require that the panels direction would need updating more frequently.

Chas

Hi capblanc,

The phenomenon is known as Brewster's angle. http://en.wikipedia.org/wiki/Brewster's_angle

What I had forgotten was it has to do with polarized light. Most coherent laser light is polarized even if it is radially. At the proper angle of incidence and angle of polarization to the window, there is no reflected light or 100% transmission.

At 90 deg. some light is always reflected and at what I would call anti-Brewster's angle 100% or very close to can be reflected.

This can be different for the solar panel crystals than for the glass.

My apologies Chas for only remembering half of it.

Brad