Series / Parallel Switching

I am a keen caravanner and spend more and more time "off-grid" using power banks and a couple portable solar panels for power.

I recently acquired a power bank which has a maximum charge voltage limit of 35V rather than the 50V charge limit of another power bank I have. Now, it's generally accepted that it is best to use a serial wiring arrangement on the two solar panels, since the output will reach the minimum charge voltage for the power banks in lower light - the voltages produced by the panels add together when wired in series -  however, in this configuration, the output can peak at 42V, which is too high for the new power bank. 

With a parallel connection the total voltage remains the same as a single panel, but the output currents add together, giving the same power output as the series arrangement, but with lower voltage and higher current. So, with is arrangement, the panels produce a maximum 21V.

I, therefore, wanted to wire the panels in parallel for one power bank and series for the other with a convenient way of switching between the two configurations. 

Here's the switching arrangement allowing series or parallel to be selected at the flick of a double pole double pole switch :