PV Overview

Battery Installation

The Rolls battery is manufactured by the Surrette Battery company. These eight 6-volt batteries are connected in series to form a 48-volt battery bank. All the recommended voltage settings for a 12-volt battery are 4 X those values for a 48-volt battery.

The temperature sensor adhered tothe battery wall is connected to the PV controller which adjusts its control setpoints based upon the actual temperature of the battery. Batteries lose rated capacity in cold ambient temperatures; they lose their longevity in hot ambient temperatures.

Here are the specifications on the battery as shown on the label. You can see that the amp-hour rating is given as 350 amp-hours at a 20 hour rate of discharge; and a 441 amp-hour rating at a 72-hour rate of discharge; and a 460 amp-hour rating at a 100 hour rate of discharge. The longer you take to discharge the battery the greater it;s rated capacity. Most PV designers use the battery capacity at the 20 hour rate, but every PV system is different.

Here are the sinister looking tools of the battery terminal task force. Each and every wire connection is a potential resistance to current flow. The greater the current running through a circuit, the greater the voltage drop associated with each of the connections.

Battery cables handle a lot of current, particularly when the inverter is heavily loaded; so good solid, low resistance, life time connections are worth the effort. These connections were mechanically crimped, and soldered solid. Then the connection was covered with heat shrink and taped with the proper color-coding.