How does connecting different solar panels in parallel affect total current?
Take a look at the equivalent circuit of a solar cell.







simulate this circuit &ndash; Schematic created using CircuitLab

When illuminated the cell acts as a constant current source IS. The shunt resistor RSH has a very high value and the series resistor RS a low value. When the cell is open circuit, i.e. no load, the constant current IS flows through the diode and the output voltage is the diode voltage. When a short circuit is applied at the output the short circuit current is, for practical purposes, equal to IS with no current in the diode.
The whole point about solar cells is that they can be connected in parallel to increase current and in series to increase voltage, which is how solar panels are created from individual solar cells. But -- a cell/panel requires requires blocking diodes to prevent a load like a battery pushing current back in to the cell/panel and panels require by-pass diodes incorporated to cater for conditions where the panels are mismatched or partly shaded.
http://www.solar-facts.com/panels/panel-diodes.php