Estimating daily solar production

[Steve]

I am interested to know the time of day my PV panels should begin to produce, as well as the peak and how many hours I can expect to get useful energy from them per day for my region.

I have an iPhone which I love very much and found some very useful applications with all kinds of solar data for my region, except production estimates. I've looked and looked and looked for a solar power app for this but haven't found any at all.

I've aquired a free application designed to help prevent sunburn. It calculates the solar insulation, sun UV output, position etc for your particular region and displays how long a person can remain outside before the sun's UV rays cause damage.

It displays a bell chart with ground UV output for the day. This is a screen shot of the application:



Question:
Can I use UV data to estimate my production?
For example, can I assume peak production shuld begin around 9am, peak around 1PM and end around 4 PM according to this graph?

I assume their screen shot was taken on a summer day. Today it shows production from about 11:30am to about 2:30PM, peaking about 1pm. It's Jan 24th today and shows no red, a UV index of only 3.4 at its peak , which I would normally expect for this time of year.

Thanks in advance.

[Mike90250]

depending on how your panels are aimed, determines where the peak of the "bell curve" is. My west pointing array, peaks at 2:30 pm generally, as the sun moves to the most perpendicular position to the panels. PV cells generate in response to white light, not UV, so using a uv reference will be wrong to begin with, and cloud cover affects the 2 differently, so it may not be close at all.

[russ]

Data from my weather station which has sensors for both insolation and UV don't show one tracking the other very well this month.

Clouds can make insolation go up substantially whereas clouds seem to always reduce UV.

[Steve]

Thank you as always for the informative replies.

I am surprised to find so few real quality apps for the iPhone for those who already have a PV installation. Lots of them to caluclate potential savings, cost etc for those considering an installation.

I've tried a few iPhone PV apps and found two which I've found useful.

One is PV Master. It has (almost) every bit of solar data for a given location and two handy calculators, one for storage battery calculation which you input the daily load in WH, compensates for system inefficiencies, battery voltage, ah etc and estimates the number of battery required to meet the load and charging perameters such as bulk and absorbtion charge.
It also has a similar calculator for PV estimates. Input your daily KWH requirement, panel size in watts, your local insulation value, overall efficiency and it gives the number of panels required.

All of this can easily be done on a calculator but I find it very handy.

The other is called SunTrack and it calculates the correct panel angles for the location and you simply put your iphone on the PV panel and it shows how far off it is.
However I consider this one kind of a fun novelty, as I adjust my panel angle by output at solar noon not by a specific degree.

[solarrules]

Grandfather clock solar tracker using time-of-day

This is a post to discuss a concept. Would it be possible or practical to slightly counterbalance a single-axis mounted solar panel so that the panel was slightly balanced to fall about its axis from East to West?

Controlling the fall (east to west rotation) would be something like grandfather (or other) clock gears operated either by batteries or spring. The gears would resist the falling and only permit the panel to fall (rotate) slowly throughout the day as the clock (time-of-day) progressed.

The unit would need reset once each day between sunset and sunrise to face back to the east either manually or by some actuator. Perhaps the spring on the clock would need rewound by pulling a chain similar to a grandfather clock.

Seems like this could make for a cheap time-of-day solar tracker. Any thoughts?

[russ]

Take a look at this site - may be helpful for this (tracker) and other purposes.

http://www.redrok.com/led3xassm.htm

Russ

[cs1248]

clock drives

This is a post to discuss a concept. Would it be possible or practical to slightly counterbalance a single-axis mounted solar panel so that the panel was slightly balanced to fall about its axis from East to West?

Controlling the fall (east to west rotation) would be something like grandfather (or other) clock gears operated either by batteries or spring. The gears would resist the falling and only permit the panel to fall (rotate) slowly throughout the day as the clock (time-of-day) progressed.

The unit would need reset once each day between sunset and sunrise to face back to the east either manually or by some actuator. Perhaps the spring on the clock would need rewound by pulling a chain similar to a grandfather clock.

Seems like this could make for a cheap time-of-day solar tracker. Any thoughts?

Grand father clocks relied on weights. A pendulum in conjunction with an escapement
gradually released the weights. "rewinding" was done by simply raising the weights again.
The "axle" part of the escapement turned the clock mechanism.
Cheap? Homebrew escapepment of scrap wood and buckets of sand for weights...Keep thinking, that's where all the good ideas begin. Sometimes we get lost keeping up with other peoples ideas and concepts...Charles

[deela]

Is there a kind of doorbell intercom system can use solar energy?