Re: Will these old commercial panels work for a small solar backup project?
Welcome to the forum.
If the panels are still good you could put two in series for a Vmp of 17.4 which would work on a 12 Volt system. However, they are only 2.5 Watts. All together (14, not 15 of them) you'd have a mere 35 Watts which is definitely not going to recharge those golf cart batteries. They would barely put out 2 Amps, or less than 1% charge rate. You need closer to ten times that much panel (about 180 to 360 Watts) for proper charging.
Four 175 Watt panels, OB MX60, 232 Amp hrs, OB 3524, Honda eu2000.
Ohm's Law: Amps = Volts / Ohms
Power Formula: Watts = Volts * Amps