The 'ybw' link is written by people who do not understand electronics very well and I think they misunderstand what the diodes are for.
You must understand that diodes on PV panels are used in two ways: A blocking diode is wired in series with the panel and it's purpose is to prevent 'back flow' when it produces less voltage than present on its load. A bypass diode is wired across (in parallel) with the PV panel and it's purpose is to allow continued flow of current along a chain of two or more panels wired in series so one does not stop the power production of the other if it becomes shaded.
Your schematic shows an LED wired so it does nothing useful at all. It might light dimly if the PV is in darkness but it would only do so by leakage current in the PV panel which would be very small. If it is supposed to light up when the battery is charging from the PV, it is wired backwards but even then it would only light if the PV voltage was more than the battery voltage + Vf of the LED so it wouldn't be useful as a charge indicator.
A simplistic way of imagining PV modules is to think of them as diodes that produce Vf across themselves when insolated. Typically each diode will produce around 0.6V (count up the number wired in series in a panel and you will see it matches the panels voltage rating!) but when in darkness they behave more like ordinary silicon diodes.
To debunk the idea that the blocking diodes are not needed, consider this scenario: You have four 6V PV modules in series to make a total of 24V, they connect directly to a battery and it charges as expected in sunlight. Now look what happens in darkness, the battery is still 24V and it appears across the ends of the four PV modules. With a blocking diode no current will flow and everything is OK, without a blocking diode the voltage will be distributed across the panels but possibly (probably) not equally so one or more panel may suffer reverse voltage breakdown. Looking at my own system here, I have two grid tied arrays, one produces 96V maximum (~300W peak), the other produces around 210V (~1.5KW peak), without both diodes it would produce significantly less power and be very prone to PIV damage.
Brian.