Interesting. I guess I've heard it all now. Some places pay more for the energy you produce than what you pay for it. Some pay the same, and obviously as your case is, they pay less. Oh, I guess there are places that still don't pay anything, so at least you get something! :)

One additional note: Early in the design phase of this project when we were first working with the sellers of the panels, I spoke of my desire to build a tracking array based on calculations that showed I could achieve a 25% gain in generation over a fixed array. We were told that it would be easier to simply increase the number of panels by 25%. It would have been easier, true, but it would have added another $6k to the project, and we were out of room because the array was already planned to be 65' long and a tight fit as it was.

For two years now, we've generated an average of 24kWh per day. The normal maximum generation on a clear day is about 4800 watts even though the array is rated at 230 x 24 = 5520 watts. It has gone as high as 6000 watts on certain days when a strange "edge-of-cloud" phenomenon happens, and the sun's light seems to be concentrated or focused by shining past the edge of passing clouds. I'm imagining pouring a concrete pad in front of the array on which I'll place reflective mylar to boost the generation during winter months while the array is in a fixed, steep angle as the sun is in a low arc. The array is wired in three strings of eight panels each, so I'll start with an experimental reflector on one of the strings in order to compare the efficacy of the reflector to the panels without a boost. The generation rate of the panels rises as the temperature falls and vice versa, so boosting generation via reflected light may not work in summer, but it has a good chance of working in cooler weather as the additional heat on the panels would be more easily dissipated.

I have a "Kill-a-watt" type device on the generation loop, so I can see instantaneous generation, and it keeps a record of daily watt-hour totals.

I've always heard of people wanting to experiment with reflective surfaces to increase output of solar panels, but I've never seen anyone actually DO it. I look forward to seeing what you come up with!

I'll see what I can do to satisfy your curiosity. mm


I just noticed that I put in the youtube search name incorrectly. The instructions should have been to search TrackingQT1 on youtube.

Michael,

I thought, I gave a lot of thought to my install. My install.

Out standing job!

I wanted a one axes system, just did not have the time. I did come up with a manual North / South tilt, it helps a little, not like yours. Once I built the platform, I had a company that installed Sun Power panels for $5k, included under ground 1 1/2" pipe to electric panel.

I have observed the magnifying effect of the clouds and the sun also. Very cool when it happens.

Had my system this Feb, 2013 for full 3 years. Last month 'Feb' bill was $2.00. I really don't pay for electricity. :eek:

With Sun Power you get free monitoring, here.

Check out, month and year values on link, cool.

Vern

Do you get any shadows during part of the day and/or year? If so, how much shadow on a group of three panels can occur until you lose the output from that group?

Since your panels are probably much cooler than roof mounted systems, you can then probably tolerate a bit more heat gain from using a reflector. I missed how the tracking is controlled - is it real time, or is it on a timer?

Another thought: does the tracking motor typically end the day at the same angle as the beginning of the next day will need? Can you "park" the angle as steep as possible in the winter overnight to minimize snow - if you ever get snow?

Hello Vern2, Nice installation! While visiting in Vemont a couple years ago, I stumbled across a utilities company that had a large array of solar panels with a seasonally adjustable north-south orientation. A couple of workers with wrenches could change the tilt of these huge arrays. You can see it from above if you go to Google Maps and look for the point where Westminster Heights Road exits going north from I-91 near Bellows Falls.

Thanks for the links. mm

Hello NeilBlanchard, The array gets a few shadows early in the morning during a short part of late fall and early spring as well as some late in the day shadows during summer when it is awake until late. The panels are in groups of eight, and it takes only a little bit of shadow on the corner of one panel to knock out the whole group. If I were doing it again, I would look more seriously into panels that have individualized inverters attached to the panel so that each panel's reaction to shadows would not affect any other panel. In our situation, shadows are only present at the very beginning or end of the day, so the loss is quite minimal.

The tracker is based on real time, that is, it connects to a GPS satellite each morning to collect the time and date, and it continues to check throughout the day. We don't have snow here...well, once every ten years or so we might get an inch or two, but in general there's no snow. The tracker parks the panels at night in a near vertical position to limit the collection of dust from cars passing on the nearby gravel road. In the morning, each day's setting comes from a look-up table based on the date and time string from GPS and varies by season. mm

Spent a few days in mendocino ten years ago on vacation .... good hippy ville :)

I always thought tracking by computer would be better then the sensors following the sun

Good job

The problem I had with sensors tracking the sun was coming up with an alternative means of finding the correct orientation when the weather is overcast. Even on an overcast day, it's somewhat better for the array to face where the sun is behind the clouds. There may be a great alternative; I just couldn't think of one. The look up tables, however, are error free and very precise, and the controller can sleep between moves which is a very low power state. It wakes every hour, moves to the place where it will be exactly facing the sun in half an hour, and after a five second motor move, goes back to sleep.