To increase wattage on cloudy days, would it be theoretically OK to connect any number of (SP350) panels to the EP500 as long as they are connected in parallel so that they don’t exceed the maximum input voltage? Or is there a limit?
According to the spec sheet (BLUETTI EP500/EP500Pro Solar Power Station | 2,000W/3,000W 5,100Wh), 1200W max, 55-145VDC max, and 20A max. You can over panel as long as the volts and amps are not exceeded (if memory serves me correctly). Here is a good read on panel configuration (Mixing solar panels – Dos and Don’ts • SOLAR POWER SECRETS).
Do not go over the voltage specs. The EP500 will use only the amps it needs, this is why over-paneling works. I have 1600 watts of power to my EP500 and only 1206 is used on a sunny day.
Regarding the amps, some folks say there no danger in exceeding the limit by over paneling on the EP500, and others say it should be avoided. I wonder what is the definitive answer to this? Is Volts all that matters, or do I have to make sure to not exceed the amps as well???
Volts is what matters and you cannot exceed. You can exceed the amps but from a cautionary standpoint I never go more than double the rated amperage.
You can go over on amps (not volts), but I wouldn’t (for example) put 50 amps into a system that can use only 10. Also, the more parallel strings and the more amps, the more you will need lower gauge wiring that can take more amps through it. Don’t make a 100 foot run on a 50 amp array with 14ga wiring, for example.
All that said, as mentioned above, “overpaneling” in parallel is commonly done in order to increase solar production in less than ideal conditions.