Perpetual Newbie & Unofficial Forum Librarian
- Dec 10, 2019
Adding to this, Victron's recommended PV array configuration for maximum efficiency is:For those using 100W panels, on a flat roof RV, 24V is far simpler than 48V… is it just too difficult to get the panels to output 48V reliably. Sure, placing higher wattage or higher voltage panels would remedy it, but the VAST majority of 100W panels are 17VMP… and in series would have a ton of shading on an rv roof… very difficult to get them outputting 65V…
For 12V batteries: 72 cells in series (2x 12V panel or 1x 24V panel in series).
For 24V batteries: 144 cells in series (4x 12V panel or 2x 24V panel in series).
Extrapolating from this, the recommendation for 48V for max efficiency would be 288 cells in series (8x 12V panel or 4x 24V panel in series) which would exceed what a common 150V or even possibly 200V charge controller is designed for. Now maybe this isn't a huge factor (this is Victron's recommended values, not their minimum acceptable values), especially for fixed installations where shade is non-existent or predictable, but it is certainly a consideration, considering that most brands small, medium, and budget charge controllers are 100V, 150V or 200V (Victron does also make 250V controllers, and some others make higher input voltage options, but not many that are geared towards mobile/marine).
*Epever also has similar recommended values from what I recall.