The high level view of how power is stored/distributed is in the diagram below.

In the following sections we'll have more details about each of the constituent parts.

The electrical system is mainly solar powered and stored in an array of batteries.

The solar panels are Conergy 260P panels. There are six panels on each side of the car path.

There are 12 NCT-13 Lead Calcium batteries. These are all wired in series. This makes the battery bank a 24V system.

When charging there is a near-constant gurgling sound. This is relatively normal but the constancy could point to the batteries nearing their end of life.

The solar panels provide varying voltage/current depending on the amount of sun they are getting. Because of this, you can't just wire them directly to the batteries, you need a controller that ensures that they are connected to the batteries when they have sufficient voltage to charge the batteries.

Because there are two arrays of solar panels, Ken made the good decision to use two separate charger controllers. Each one is a MidNite Classic (I am pretty sure, that they are Classic 250. I am unsure if they are the SL (solar only) or the 'normal' ones.

It is common to see one of the output controllers doing a lot more work that the other. Here's an example from a particularly sunny day:

While their input is relatively similar (66.3V vs. 63.7V, respectively), their _output_ is very different: 0 Watts/0.3kWh vs. 401 Watts/6.9kWh, respectively (it's a happy coincidence that the lower input controller is actually providing more output because the input, as long as it is above the 27V threshold, is irrelevant for the differing output.

The output differs because the controllers 'back off' when the charge of the batteries is near their capacity. In this case, the controller on the right is observing a slightly lower voltage and is using the power from its panels to charge and/or hold the batteries at that voltage. The other controller sees that the batteries are at or above their voltage threshold and determines that there is no work to do.

This is expected behavior mid day when the batteries are nearly fully charged.

In the morning when there is sun but the batteries have been drained over night, we should see both controllers providing output. The following is a photo from a morning charge on an overcast day:

From the MidNite Classic documentation:

Trusting a State of Charge (SOC) meter, which can lose calibration over time and give you false readings. You need to verify specific gravity and or verify the charge voltage is being met. Never fully rely on the SOC %; it is just a good, quick referenc

Check the calibration of the State of Charge on the MidNite Classics

The MidNite controllers and the battery bank are connect to a Trace Engineering DC Disconnect.

batterylist