OK, The more panels in parallel the higher the current, the more in series the higher the voltage. The cell size= amps - any cell regardless of size produces a given voltage and for most cells that happens to be around .500 vdc. or ½ a volt. And the size of the cut cell indicates to current. All the cells I have are rated for .500 vdc or ½ volt @ 3 amps.
This means that any cell hooked in series is doubled in voltage. Any cell hooked in parallel with another cell is doubled in current or amps. Example; 2 in series=.5+.5=1vdc -> 2 cells in parallel will produce 1/2vdc and 6 amps.
It does not really matter how you hooked them up provided that, no matter what you must meet the charging voltage or your batteries and the controller. This is why when you look at most installations, you will see that 4 panels are hooked in series and then all the rest are generally hooked in parallel to increase the amps only after the charging voltage has been met. Most installations use both series and parallel hookups.
As far as matching is concerned. Again this is a simple case of the size. It is best to match the main panels to produce a charging voltage and then you can use mismatched panels to cover the current in parallel.
The smallest size panel in any series will be the net result of all the output (even if the other panels are larger, the smaller panel will dominate. However in parallel it does not care and just adds the current. This is why the matched panels are used for compliance for charging voltage and the -don't care about size dimensions panels are placed in parallel. Makes sense?
Now as far as how many cells you put into a panel in series is as far as I am concerned totally flexible based on this above information.
So, here is the criteria to help you decide quickly how to make a panel. First and foremost is the controller. What does the controller require to keep the batteries charged no matter what? I like to be a bit above this by a factor or 3 or more. That way the charging voltage is always met even in a cloudy day. A rough estimate would be about 28-33vdc or slightly higher. This would also allow for compensation for losses. (wire resistance, controller heat and internal losses for conversion etc).
In my panels I have 28 cells hooked in series, this produces .500 x 28 = 14 vdc. And I hook 2 in series this us 28vdc. The controller voltage is met. The battery charging is met. And produces 3 amps. The controller will later convert the voltage and current to produce a full charge voltage of about 13.8 vdc and increase the amps from voltage not used during conversion. It's hinged on what the controller requires and can put out. Now here is the interesting part. Since the charging voltage and controller voltage has been met the rest of the panels (10-20) are put into parallel. Increasing the amps way up. In this case, 3ampsx10 panels=30+ amps or 3ampsx20panels=60+amps. @ 13.8 x 30amps= 414 watts or 828 watts.
The neat part about my panels is that for some reason for which I can't explain is that my panels are putting out 16.5vdc @ 3 amps each giving me a total of 49.5 watts each panel.
In my case I have already produced 12 panels and am continuing to create more as we speak. I figure I have enough to make about 20 or so panels. Each panel produces
You can also opt for hooking a large majority of panels in series to produce 128vdc @ 3 amps and then let the controller sort out the amps. It is more efficient and produces less loss. But the expense of the controller is the question.
Hope some of this makes sense and clears it up.. I wish you good luck and keep us informed.
