Things that Work! The SunAmp Power Co.'s PV Regulator Richard Perez This regulator is simple to use, reliable, and inexpensive. The SunAmp Model PBRS regulator is 100% solid state (no relays), using a MOSFET transistor as a switch. The regulator is temperature compensated and available in just about any voltage limit. It is ideal for small photovoltaic systems. The SunAmp PBRS Regulator This regulator is a different type than the series PV regulators we have discussed before. This regulator is actually a shunt type that shorts out the PV array when the battery voltage reaches the factory set limit. The FET switch is on the array side of a blocking diode, so current can only travel in one direction -towards the battery. When the FET shorts out the array, it does so on the array side of the diode and the battery is not shorted. This novel approach eliminates the need of a shunt load and results in a very cool running regulator. Test System I installed the PBRS12-4LA regulator in my small auxiliary PV system. This system uses a single ARCO M75 PV module to refill a 110 Ampere- hour RV deep cycle, lead-acid, battery. I use this system to power up instrument and regulator tests. When I'm not actively using it, it tends to overcharge. A perfect place for the SunAmp regulator, I mounted it next to the batteries. There are four wires to hook up- plus & minus from the array, and plus & minus to the battery. The PBRS12-4LA is rated to handle 4 Amperes of current and has a voltage switch point of 14.5 VDC. The SunAmp factory can set the regulator up for whatever voltage you require- from 13.5 VDC for cranky lead-acids to over 16 VDC for nicads. They make models that will handle up to 18 Amps and models for 24 and 48 Volt systems. Regulator Performance It works well, indeed. There was virtually noticeable heat build up when the regulator was operating. Voltage switch point was within 0.06 Volts of where SunAmp said it would be. There is a internal temperature sensor that raises the voltage switch point when the regulator (and the batteries) get cold. The unit is equipped with a TransZorbtm surge protector to guard against lightning. Conclusions The SunAmp Model PBRS are very effective and inexpensive in small PV systems using less than eight modules. They are temperature compensated, available at a variety of voltage switch points, and carry a five year warranty. The 4 Amp model I tested costs $46, which is inexpensive considering its features. Other models cost between $45 and $113 depending on Amperage and Voltage. Access SunAmp Power Co., 8502 East Cactus Wren Road, Scottsdale, AZ 85253 ù 602-951-0699.