Solar Project: Grounding the System

Continued from Solar Project: Figuring Out the Wiring

Earth ground symbol

Electricity follows pathways. Typically, that's the wiring between the source and whatever requires electricity to operate. If there's a problem, it can jump the wiring and electrify nearby metal. This could be deadly to someone who touches it. Physically connecting the wiring to the earth gives the electricity an alternate pathway, if needed. Called grounding or earthing, this is an important safety feature.

Many solar setups tie all the components together and ground them as a unit. If we had been thinking several steps ahead we could have done that too. Because we were doing this one step at a time, Dan grounded the solar panels separately, as specified in their installation manual.

The grounding holes in the solar panels' aluminum
frames are marked with the earth ground symbol.

Lay-in lugs connect the neutral grounding wire to the panels.

This photo makes it look like the wire loop on the right is
touching itself. It's not! It's just the angle of the photograph.

The grounding wire is connected to a grounding rod.

Alternatively, the ground wire could have run
through the underground conduit (white
pipe sticking out of the ground) to the battery box.

At the battery bank box, the charge controller and inverter are grounded together. Each clearly shows where the ground wire attaches.

Charge controller innards. Ground wire on the right.

Inverter ground wire on the right.

The ground wires from the charge controller and inverter are connected in the battery box with a thingy called a busbar.

Busbar with two of the three ground wires attached.

The third wire above (yet to be attached) will connect the busbar to the grounding rod. The ground wire from the panel array could have been connected here too. The busbar is a conductor and will direct wayward currents from either the controller or the inverter to the ground rod.

Our second ground rod near the battery bank box.

That's a very important step accomplished!

Most of the cables are in place, but they aren't connected yet. There are a few more things to do first, and then we can put the system together.

Next - Finishing Up Odds and Ends

Solar Project: Grounding the System  © Jan 2020
by Leigh at http://www.5acresandadream.com

Solar Project: Figuring Out the Wiring

In my last solar project update, I showed you the battery box Dan came up with. The batteries and charge controller are now installed in the box, so the next step will be connecting all the components together.

For that, we need various sizes of cables and circuit breakers.

To understand how it all fits together, I drew a diagram.

You should be able to click to biggify.

Cable size is based on current (amperage), so they become progressively larger as the electricity travels from source to use.

I used the sizes recommended by Prepper's Total Grid Failure Handbook and the charge controller user manual.

• 10 AWG from solar panels to charge controller
• 2 AWG from charge controller to battery bank
• 4 AWG golf cart battery interconnect cables between batteries
• 1/0 AWG from the battery bank to the inverter

The manuals helped me size the circuit breakers too.

Solar is a direct current (DC) system, so all of these are DC circuit breakers. Household (AC) circuit breakers are not recommended.

• 30 amp (12-72 volts) between solar panels and charge controller. The formula is the PV array's short-circuit current (LSC) multiplied by 1.56. The LSC is listed on the back of the panels. For us, that was 6.39 x 3 panels = 19.17 x 1.56 = 29.9 or 30 amps.
• 60 amp circuit breaker between the charge controller and battery bank was recommended in the charge controller manufacturer.
• 175 amp circuit breaker between batteries and inverter was recommended in the inverter manual.

They are marine breakers, so they are waterproof. Even though they will be installed in the battery box, that still seemed like a good idea.

All of that is probably more technical than you're interested in, but I want to have all the information where I can find it. That's in case we need it for future reference. A blog comes in handy for things like that!

The next step will be grounding the system.

Solar Project: Figuring Out the Wiring © Jan 2020

by Leigh at http://www.5acresandadream.com

Finishing That Corner of the House

One year ago, we finished re-siding the back gable end of the house.

December 2018

At the time, I assumed Dan would also finish off that last back corner. The one in the above photo with the old white vinyl siding. Alas, Dan quickly shifted mental gears from the house to the carport. So that corner has remained an eye magnet for the past year.

Last month, he finally got to it when it became one of the side projects of installing our solar system.

The wiring from the batteries must go through that wall to the inverter (which will convert the batteries' DC electricity into AC electricity for the freezer). The freezer will plug into the inverter on the back porch.

We had a string of really nice days right before Christmas, so Dan got started on this project. The first step was to remove the old vinyl siding.

Thankfully, no surprises there. The original shiplap siding looked the same as it has on the rest of the house beneath the vinyl siding.

The wood siding came down next. No surprises there either. Dan had insulated that wall years ago when he replaced the back porch floor.

The back porch steps were obviously added on after the house was built. You can tell because the old siding runs behind the concrete.

The next step was to remove the back porch overhang bracket, the porch railing, and the old corner molding.

That meant the porch overhang had to be propped. Tar paper was next and then our barnboard siding.

The siding fit behind the porch steps and storm windows perfectly.

The last of the construction part was a new overhang bracket.

The wire you see runs from a small solar panel on the roof to a vent fan behind the crawlspace door. (The panel that contains the fan can be moved as needed.)

This is one reason why the battery box is in such a good place. In summer, the cool vented crawlspace air can blow across the batteries.

After painting the siding, new corner trim and porch railing were added.

Dan finished with the painting before we got another round of rain. At last, the back side of the house is done!

December 2019

Well, maybe I shouldn't be too optimistic about that. Now, he's talking about replacing the back porch overhang and maybe re-doing the back porch steps. It never ends, does it? 😄

But first things first, and that means connecting our solar panels, charge controller, batteries, and inverter. Then we can plug in the freezer! More on all that soon.

Finishing That Corner of the House © Jan 2020

by Leigh at http://www.5acresandadream.com