I haven't written anything here for a long time, my bad, but I don't have much to say about the excavation challenge right this second either...
The next beam power challenge is coming up this Fall, and it's not too far away. I once thought about entering, but I just don't have time for both contests. So, I will give some design secrets away to those who are in the contest, and happen to read this. They might not be new to some, but they are design approaches that I intended to use.
PV panels exhibit some interesting properties regarding the relationship between their voltage and current outputs, and some side-effects because of the way they are built; individual cells wired in series. This means that unless the entire panel is illuminated evenly, you may get only as much as the least illuminated portion, which might be dark, hence zero output.
Here is what I wanted to do.
First, make your own panels from individual cells. Wire them in series, and put a reverse-biased germanium diode across each cell. This way, if a cell is dark, current generated by other cells can pass through instead of being blocked.
Next, wire the cells in long strings to produce 70 - 100 volts, and connect them to a power point tracking (PPT) regulator, which is really a DC-to-DC converter with a constant output voltage. However, there is an important addition. PV cells output their peak power at a certain voltage and current, which is controlled by the load impedance. The true PPT regulator adjusts its input impedance to operate the cells at this point.
The other part of the above design is that even when illuminated poorly, you might still get 20 or 30 volts, for example, and while this won't translate into a lot of POWER, at least you will get something. Whereas, with a 12 volt panel, running at 18 volts fully illuminated, you might get 10 volts when poorly illuminated, and that does nothing for a 12 volt system.
So, in my opinion, these three features can add greater chances of success to beam power challenge teams. It isn't rocket science, just squeezing every watt of power possible out of a PV system.
In summary:
1. Construct panels from strings of cells with reverse diodes across each one.
2. Make the strings long for higher available power.
3. Use a PPT regulator to step-down the high voltage, and operate at maximum power.
Good luck,
Jim
[ 1004 comments ] ( 14736 views ) The next beam power challenge is coming up this Fall, and it's not too far away. I once thought about entering, but I just don't have time for both contests. So, I will give some design secrets away to those who are in the contest, and happen to read this. They might not be new to some, but they are design approaches that I intended to use.
PV panels exhibit some interesting properties regarding the relationship between their voltage and current outputs, and some side-effects because of the way they are built; individual cells wired in series. This means that unless the entire panel is illuminated evenly, you may get only as much as the least illuminated portion, which might be dark, hence zero output.
Here is what I wanted to do.
First, make your own panels from individual cells. Wire them in series, and put a reverse-biased germanium diode across each cell. This way, if a cell is dark, current generated by other cells can pass through instead of being blocked.
Next, wire the cells in long strings to produce 70 - 100 volts, and connect them to a power point tracking (PPT) regulator, which is really a DC-to-DC converter with a constant output voltage. However, there is an important addition. PV cells output their peak power at a certain voltage and current, which is controlled by the load impedance. The true PPT regulator adjusts its input impedance to operate the cells at this point.
The other part of the above design is that even when illuminated poorly, you might still get 20 or 30 volts, for example, and while this won't translate into a lot of POWER, at least you will get something. Whereas, with a 12 volt panel, running at 18 volts fully illuminated, you might get 10 volts when poorly illuminated, and that does nothing for a 12 volt system.
So, in my opinion, these three features can add greater chances of success to beam power challenge teams. It isn't rocket science, just squeezing every watt of power possible out of a PV system.
In summary:
1. Construct panels from strings of cells with reverse diodes across each one.
2. Make the strings long for higher available power.
3. Use a PPT regulator to step-down the high voltage, and operate at maximum power.
Good luck,
Jim
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