Question: I want to make a simple off grid system. I plan to use the 250 or 260Wp panel, a simple 10Amp PWM regulator and a 12V battery. Will this work?
Answer: this configuration will work, but it will not be effective and you will not gain the full solar power from the panel.
The PWM regulator is designed to work with solar panels that have the „maximal power point“ (MPP) close to the battery voltage – typically around 15V. This regulator is not designed to work with large panels that have the MPP voltage much higher. The 250Wp panel has the MPPT around 30V.
The PWM regulator connects the battery directly to the panel. This means thevoltage of the panel will be pushed down to the voltage of the battery. As a result the panel will provide only part of the energy.
The 250 to 260Wp panel works best at some 30V, and it is able to provide around 8.5A of energy. This makes the maximal of 250 to 255 Watts (all numbers rounded).
However when you connect the 250Wp panel thru the PWM regulator to the 12V battery, the panel voltage will be pushed down to the battery voltage. This meansthe panel will work only at 12V with 8.5A, it will supply only some 100W of energy.
The PWM regulator will not work with the large size panel effectively. It is recommended to use the MPPT regulator for such a configuration. (See details about the MPPT voltages and power ratings here).