This charge controller must be used in small-scale systems. Manual disconnects may be needed on the battery and solar panels to prevent the battery from being exhausted by the power draw of the controller. The information listed on page 24 (last page) of the user manual must be reviewed carefully and then look closely at the wire connection ports on the bottom edge of the controller. (Please see the attached pictures.) In a twelve-volt system, the maximum power input is 300 watts, with the input voltage being less than 60 volts DC. So, if you are close to the maximum voltage, then the maximum amperage should be around 5 amps (or less). After all, sixty (volts) times five (amps) equals three hundred (watts). Two one-hundred-watt solar panels in series would provide a power input that should be less than the maximum power input of this charge controller. The wire connection ports on the bottom of the controller are, in my opinion (IMO) too small for anything more than 14AWG wire. I normally use 10 AWG PV cable, but that size cable would never fit these ports. The same is true for the rest of the ports, that are for the battery and the load. Perhaps 12 AWG wire might work, but I do not have any to test with this controller. So, if we are using 14 AWG wire/cable, then we need to be working with relatively small loads. Obviously, as the wire diameter decreases, we need to reduce the amount of current we are pushing through this system, or we will have increasing resistance losses (undesired heat). Finally, this charge controller always consumes 44 mA, whether the panels are producing anything or not. On a cloudy winter day, this system may/will drain the battery. As one other reviewer mentioned, you need to be able to power down the entire system, so as not to drain the battery on marginal/nil days. (I recommend going through all of the reviews on this controller for ideas on how to design an effective solar power system with it.) From what I understand, this charge controller requires sufficient power from the battery for it to function. Once the battery is effectively dead, then the charge controller shuts down and your system is done until you recharge the battery. Excellent sunlight on the panels will not cause the controller to turn back on, if the battery is dead. Any system must be monitored, but this one must be closely monitored or just simply shut down to save battery power. This charge controller is worth four stars as it has good controls and a good heatsink. You just need to consider the limitations of the cabling and the battery and load as you are putting a system together.