Electrical wiring, batteries, inverter
Electrical is not as hard as some my worry it to be. It does seem daunting, but it is relatively basic. You will probably want both AC and DC. That is what we did. The DC power is provided through the batteries. More on batteries later. The AC is from an inverter that converts 12 volts DC to 120 volts AC. You then plug directly into the inverter or run a wire from it to where you need power. We have both options.
In the picture below you also see several components. If I had to do it again, the one that I would change is the breaker (grey box on the wall). It was really not needed as the inverter already has one, but we thought it would initially help. Now that I have used the van for a while, it draws so little power that the breaker is really not needed; we could rely on the one built into the inverter. We also installed several ‘shunts’ that are places we can hook up monitoring devices to see what power is being used where. More on that later as well.
Researching the electrical took a bit of effort and we had a few calls into the inverter folks to get clarification on what we were seeing. It turns out vans (any vehicle) has some differences from the house AC regarding breakers since vehicles do not have an earth ground. We also installed three shunts (to the right of the breaker) to help monitor incoming solar, charge to the battery and overall 12 V load.
Items in the picture from left to right:
Black box (with Rover on it): Controller from the solar panels to the battery
Grey box: Breaker for the AC voltage
Black and brass items below the black and grey boxes: Solar fuses
Three metal horizontal strips: Shunts that connect to the monitoring meters
Black box with clear cover: 12 V fuse box
On horizontal flat surface: 3000 watt pure sine wave inverter
Black boxes on the floor in back: Batteries
One item you cannot see: Battery to battery charger
Controller for Solar Panels
See the solar section for more information, but this part is simple. There are two wires that come from the solar panel into the controller. The controller does some solar ‘magic’ and converts it to the right volts and amps to maximize battery charging. In the end all you really need to know about the controller is two solar wires go in and magic happens and there are then a couple of wires that go out to charge the battery. In the solar section we will also mention some key cut-offs and fuses. The controller is very easy to hook up.
Batteries
The solar controller feeds back into the battery. We call the batteries our ‘golden batteries’ because lithium batteries are so expensive. They are worth it though. You can drain them to empty and they weigh less. We have another section on batteries, but for this blog, solar feeds batteries and then batteries feed the inverter and 12 volt fuses. We connected our batteries in parallel. That is positive-to-positive and negative-to-negative. That provides 12 volts, but since each is 170 amp-hours, it has a total storage of 340 amp-hours. Again, see the battery blog for more info on this including our brand recommendation.
Inverter
Pretty simple here as well. The back of the inverter has two places to connect a wire to the battery. You need to use heavy duty wire (suggest size 4/0) and it can be purchased with the lugs (connectors) on the ends or you can put them on yourself with a few simple tools. We did both. Once you hook the batteries to the back of the inverter, the inverter does inverter ‘magic’ and out comes 120 volts. Mine (and most) have outlets that you can plug directly into, but mine also has a place to connect normal wiring to use for 120 volt circuits so I can install outlets wherever I want them.
12 Volt Fuses
From the battery you can also connect to a fuse panel for all 12 volt outlets. You connect wires from the battery to the fuse box and then you run wires from there to wherever you need them.
Battery to Battery Charger
This is not in the picture as it is hidden below the red wires in the picture, but there is a battery to battery charger. It connects from the van battery to the lithium batteries. That way when I am driving (or have the engine running), it also charges the lithium batteries along with solar.
I Said it Was Easy, So Here it is Again
How do I get power to the batteries? The solar controller connects between the solar panels and the batteries. It does some ‘magic’ and finds the most optimum settings to charge the batteries the fastest. You also can charge the batteries by using a battery to battery charger which will charge the house batteries with the vehicle when it is running.
How do I get 12 volt power? Connect your batteries to a 12 volt fuse box and then connect wires from all 12 volt lights, outlets, etc. into the fuse locations.
How do I get 120 volt power? Connect your battery to the inverter and it does its own ‘magic’ to convert 12 volts to 120 volts. You can then plug into it or run wires to wherever you 120 volts.
Watts / Amps simply put:
Watts x hours = Watt-hours (Wh): Power usage of your electrical devices are commonly measured in watts. How many watts does your device draw. How many hours or fraction of an hour will you use a particular device in a day, your Wh. Add up the Wh for all your devices for your total Wh usage in a day.
Wh / 12V = ah: Batteries use amp-hours to measure capacity. So you have to divide your Wh by 12 to get total Ah. This helps you determine your battery requirement. AGM or lithium? Remember that AGM batteries can not be depleted below 50% of their capacity but lithium batteries can go all the way down although best to not go below 10%.
Wh / average amount of daily sunlight = solar panel Wattage needed: Your total Wh consumed during the day will determine the number of panels you need to keep your batteries charged up for your daily power consumption. Just remember that your direct sun will only be about 5-6 hours and there will be days of overcast, shade, rain, and winter when the sun is lower on the horizon. Consider panels that you can tilt to maximize the sunlight.
See simple. Don’t be frightened by it. In other blog posts we go into more detail such as which wire to choose, what fuses to choose, outlets, dimmers, battery recommendation, etc. But for now this is the basics for electrical.