How do we get our typical household 120 VAC current from a 12-volt battery? Let’s take a look at a simple inverted system which provides that function.

Warning!!!

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See further below for notes and additional YouTube video.

In the previous episode, Basic System with a Battery, there were a few limitations/problems:

* It required a voltage-matched solar module

* With a larger solar panel, it was subject to overcharging the battery once the battery was fully charged

* A higher-voltage PV module would over charge the battery

* It did not supply 120 VAC home power

With our new off-grid system configuration, we will rectify all four of those issues.

This is the forth episode in the Going Off-Grid series. To start at the beginning, go to episode 9, Going Off-Grid – Introduction.

Going Off-Grid – Simple Inverted System – Video Portion

Our New Example Configuration

1. Solar Panel

We have replaced the small 12-volt trickle charger solar panel with a 72.5 watt First Solar FS-272 monocrystalline solar panel. Its MPP voltage is 67.9 and MPP amps is 1.07. We will focus on solar panel technology in more detail later.

2. Solar Charge Controller

This is a new addition to our example configuration – Renogy Rover 20A MPPT Charge Controller.

* Maximum Power Point Tracking (MPPT)

* Nominal System Voltage: 12V/24V Auto Recognition

* Rated Battery Current: 20A

* Maximum Solar Input Voltage: 100 VDC

* Maximum Solar Input Power: 12V @ 260W; 24V @ 520W

Renogy is a solar equipment manufacturer in the sweet spot of smaller systems. This charge controller has many additional features I didn’t cover in the video. I really like their products. You can view this and other Renogy products on Amazon -> here.

3. Battery

We are using the same 12 volt deep cycle marine battery as in the last video. Deep cycle batteries, though using the same lead acid technology, are different from car batteries. Deep cycle batteries can be discharged more deeply and more often than a car battery. Car batteries can put out more power for shorter periods of time (cold cranking amps). We will cover batteries in more detail in a later episode.

4. Inverter

Cobra CPI-2575 2500 Watt 12 Volt DC to 120 Volt AC Power Inverter is another addition to our example configuration. Since we didn’t have power on site while building our home, this inverter provided ALL of our power needs for months before we put in our whole house off-grid system. It ran everything from coffee machines to saws to air compressors with absolutely no problems whatsoever. You can view this and other Cobra Inverters on Amazon -> here. I’ve also been very happy with Bestek Inverters, which you can view on Amazon -> here. We will cover other types of inverters in more detail further into the series.

5. Load

Instead of the 12-volt DC fan, we now have a standard household 120-volt AC power drill.

Schematic

The diagram for this configuration is slightly larger than the previous system,