Broken Solar Panel, part 4

My Broken Solar Panel: Wiring it up to the batteries

To some this might seem like a lot of work for "just an experiment." You might be right, however, the tests we did with the solar panel so far indicate it will put out a reasonable amount of power. Having said that, I don't think all will be lost if we continue to make the installation look professional. The panel may end up being a long term work horse that is quite capable of performing very well. Time will tell of course.

Attach the solar panel to the frame

[ photo of panel bolted to frame with small B-Line bracket ]

This photo shows several things. Closeup is the little B-Line bracket bolted to the mounting frame and to the frame of the solar panel. The B-Line brackets were bolted to the mounting frame and positioned to the correct angle in part 2 when the frame was being built. I installed long bolts into the solar panel frame so they would stick out the back, you can see the extra nut against the solar panel frame. Then I carried the solar panel outside and hooked the protruding bolts onto the frame brackets. That way I didn't have to balance holding the panel while fussing to get a bolt started into a hole. I really try to make things easy for one person to install and work on.

The other thing this photo shows are the galvanized pipe sections between the concrete and the base of the frame. I cut them from a 2 foot pipe I purchased at a local home improvement center. The pipe sections accomplish two things: 1-they give horizontal stability to the 3/8 inch threaded rods holding it in place, 2-each one is a slightly different length to precisely level the base of the frame. I tightened the nuts on the 3/8 inch rod fairly snug to compress the pipe sections between the frame and concrete. I tested the strength by pushing and pulling the frame sideways and found that it would not move. It should hold firm in any windstorm we might have.

[ photo of mounting at the base ]

Here you can see the slightly larger B-Line bracket attached to the base of the frame. I had to use a section of 2 1/4 x 1 1/2 inch B-Line to make this bracket so the bolt hole would reach the hole in the frame. With a little different perspective you can see how the galvanized pipe fits between the frame and concrete. I used a large "fender" washer on top of the frame to keep from bending the frame when the nut is tightened.

[ photo of solar panel installed ]

Here it is outside in the sunshine.

Wiring the panel to a disconnect / fuse box

[ photo of disconnect and fuse box attached to the frame ]

The wiring first goes to a disconnect switch box. This will allow me to work on wiring in the house safely by shutting off power coming from the solar panel. The disconnect box also has over current protection in the form of a fuse in case something should go wrong.

[ photo of solar panel wiring ]

Wiring from the solar panel itself isn't pretty because it doesn't have a junction box on the back. The two wires go into protective sheathing to protect them between the solar panel and the disconnect box. This is the same 12 gauge THWN wire that I used to rewire the solar panel to put out 60 volts.

[ photo of wiring to disconnect box ]

Extend the wiring to the house

The wiring exits the disconnect box through conduit which is buried in the ground for a short distance, about 10 feet. At that point the conduit emerges above ground again.

[ photo of conduit emerging above ground 10 feet behind solar panel ]

[ photo of conduit where it joins existing wiring in another conduit ]

Here the new wiring is merged with existing wiring. Part of the existing conduit wiring here is where the "old" 48 volt panels previously connected to the batteries. The old part has a new purpose and is not used with the broken solar panel.

[ photo of conduit installation painted to match house color ]

If I keep things looking nice the neighbors might not complain about "my experiments" in the yard.

[ photo of broken solar panel with other solar things in my back yard ]

Inside the house

[ photo of junction control box ]

Here is where the solar panel connects to the batteries. There is a lot going on in this steel utility box.

1. The terminal strip (lower right) solar panel wires are left most black/white pair. This is the main entrance. The other connections to the right are 48 volt DC outputs for appliances. A terminal block below that is where the battery bank connects, red/blue pair emerging from flexible conduit.
2. Across the top of the box are fuses for inputs, outputs, monitoring and charge controller.
3. The gray box (upper left) is the charge controller. It adjusts the amount of current going into the battery bank, depending on the state of charge of the batteries. It's reading 55.2 volts. The green LED (left) indicates "charging", LED (right) indicates battery in "good" condition.
4. Black and red square box (lower left) monitors battery conditions such as amp hours taken out and put into the batteries, voltage, current in or out, and a number of other things. With this device you can tell the condition of the battery bank by reading just two items: voltage and amp hours.
5. The top meter (right) reads amps from the solar panel, 1 amp full scale. I replaced this with a 5 amp full scale meter for the higher output of the broken solar panel. The bottom meter reads voltage, 100 volts full scale.

[ photo of 48 volt battery bank, 4 x 12 volt batteries wired in series ]

Batteries on the middle shelf comprise the 48 volt battery bank in this system. Four 12 volt 33 amp hour sealed lead acid batteries. The red/blue wires from each battery come together in a junction box in the middle where they are wired in series. The flexible conduit on the left side of the box is where the 48 volt wires connect to the control box in the previous photo. Each battery has its own in-line fuse for safety and disconnect. The clear plastic tube on each red/blue pair of wires coming from the battery is the fuse.

How is all this working?

The broken solar panel has been charging these batteries since 10-7-2012. The batteries are fully charged and even go into "float" mode on cloudy days. With the original 40 watts of solar panels that would not happen.

One day the battery bank was low because I had used it for charging my netbook and laptop computers and to run the wireless DSL router the previous evening. The next morning was cloudy and very little current was going into the batteries. When the sun finally peaked out from behind the clouds I saw 2.5 amps go into the battery bank at 54 volts, that's 135 watts! Not bad for a broken solar panel that almost went into a dumpster!

I have been using the 48 volt system to do a lot more at my work bench. I am very pleased with this. I would say the "experiment" is a success.

Photo Gallery

Broken Panel

Pouring concrete

Mounting and wiring

Gregg Scholfield    2-14-2013