Now we come to our battery bank for our Solar system. This one is made up of six volt cells combined in different ways to get the voltage we need for our individual inverters. We're going to be using the big Zantrax 1,000 watt this time, so we'll need two six volt cells, in series, to come up with that twelve volts. If you take your battery and connect a positive to a negative terminal that leaves you with a positive and negative terminal and you can get your twelve volts here. If you connect four batteries in series, positive to negative, you come up with twenty-four volts. And if you needed a forty-eight volt system, which is not uncommon, you'd simply expand and use more batteries. But for a twelve volt system we'll just use two. And, they're really the most dangerous part of the system. If you look down inside there, you can see a liquid and that liquid is sulfuric acid and will really seriously burn you and that's why we have a base here, Baking Soda, and if you get that acid in your eyes or in your clothing you can neutralize it with this. So, very important to have this for safety. We can get a look at some of that acid here with the hydrometer, this is what you measure the actual specific gravity of the acid inside. And you can see we have several of these disks floating. We have about three disks floating with one at the bottom. So we know that this two batteries, or at least this battery, is about seventy-five percent charged. So, we're going to be very careful with that acid and stick this back here in our little cup. It's also important to note that the gases that come off of these batteries, or just about any kind of battery can be hazardous as well. In fact, the Hindenburg was filled with the hydrogen gas that comes off the batteries and we know how that went. So, explosive gases and dangerous liquids, be very careful.