Solar Voltaic setup notes

These are some notes made by a plumber off a youtube video describing how some random guy built a solar setup, perhaps for no better purpose than making the youtube video. So you can maybe use it for a conceptual education, so long as you think it through yourself and fix my errors, and preferably get a licensed electrician to approve your plans. I offer you these notes not as reliable plans to work from, but to help us both get a sense of the lay of the land while doing background research. As always, please take responsibility for your own choices, design, sizing, workmanship, etc.

Meanwhile, this might be informative, so here we go.

• A perhaps typical target spec for a home solar system is 12V X <2000Watts, same power as home outlet (120V*15A = 1800W).

• That is, everything is 12V(DC)in this setup. We use an inverter to create 110VAC for regular household electric appliances.

• The conceptual architecture of the system is that everything important is connected in parallel from and toward the bus bars, one positive and one negative, which are distribution points from everywhere to everywhere.

  So the juice comes in from the solar panels through the charge controller on to the bus bars, then it goes everywhere. Mainly it feeds the batteries, but that goes and also comes, since without sunlight the batteries then push back and power the bus bar, and the bus bar powers the 110VAC inverter as well as a convenient 12V receptacle box.

  Thats basically the whole design, except that we add fuses on the hot sources, switches to isolate the potentially-live power sources (panels and batteries), and a shunt to a battery monitor.

  In the description below, a | symbol can denote the two wire connection, while a positive or negative item +x or -y will be only on the positive or negative side of the given path. Fuses are on the positive wires and are located where they will do the most good, that is, on the end where the big flows come out on the given link.

  So:

  • Solar Panels | +-switch | Charge Controller | +fuse1 | bus bars.
  • Inverter | +fuse2 | bus bars
  • 12V multi-receptable a.k.a. Fuse Box | +fuse3 | bus bars
  • Batteries | +fuse4 | -shunt | bus bars
  • Battery monitor | -shunt | +battery1

• (Annotating x|y for a connection emitting from an X and going to a Y), we have
  Solar Panels p|c Charge Controller c|b Batteries* b|i Inverter* i|o 110VAC Outlet
  *: rated for 12V and 2000W

• The flow of juice goes from subunit to subunit via endpoint-specific connections

• Each of these | symbols is one or two wire connections, for which size must be calculated.

• We will use the Power formula to size things: Watt = Volt*Amp.
  So also W/V = A: Watts / Volts = Amps. Considering the inverter, then: 2000Watts / 12V = 166.67Amps.

• Also we have the normal outlet sized as 120V * 15A = 1800Watts. Thus the popularity of a 12V*2000W system.

• Sizing applies to wiring, lugs, fuses, switches, shunts and bus bars. All via the Power formula, where Amps determine | wirings and switches sizing.

• Example: Battery to Inverter wiring: b|i.

  b|i inverter wiring needs to support 166A/0.85 = 196A (derated because 85% efficient so we need extra juice into it).

  From the wire sizing tables, look up 196A, find the range 150-200A, and go one size up. Also consider going larger in case of long runs like p|c panels to charge controller. But b|i < 3M, so no run length adjustment, and thus 2-0 gauge wire is selected for b|i.

  As an example.

• Now you can go figure out the different wiring sizes between:
  • b|i Battery | inverter: 196A ++ so 2-0 gauge.
  • p|c Solar panels to the charge controller
  • c|f the charge controller to the 12V fuse block
  • f|? the 12V fuse block to the system
  • ?|r the system to the bus bar.
  each based on amps and distance...
  • Size the cable lugs to the ends of our wires for those plus switches.

  • Size the screw internal diameters to connect the lugs to (on the bus bar)

  • Size the fuzes for max amps on each wire, located on the sending element x and before the wire x|?

  • Size the switches to disconnect the solar panels from charge controller and to disconnect the batteries from the system for maintenance. 275Amp switch on the panels.

• Bus bars are distribution points, connected to with posts/bolts/screws.
  Positives tie to one bar (red) for battery, inverter, charge contoller, and 12V fuse block.
  Negatives on another bar (black).
  
• A shunt is used to connect battery and power to a battery monitor.

• Do a layout drawing as you like, e.g., on a mounting plywood sheet.
  Make a diagram on paper before starting.

• Mount the inverter to the plywood for convenient access to its plugin outlet.

• Consider how to make a wire connection, with the example b|i:

  b|i uses thick (2-0) wires so do this first.
  Run positive wires from inverter positive to fuse, fuse to positive bus bar, positive bus bar to switch, switch to wire going to positive terminal of batteries.

  Run negative wires inverter negative to negative bus bar, negative bus bar to shunt, shunt to wire going to negative terminal of batteries.

  These heavy gauge wires need a big (bolt) cutter and lug mounting tool (hammer driven pin into lug over wire).

  Do layout first, place posts and lugs where you like, then measure the cable bits to cut.

  Mount lugs facing out from their mount locations.

  Shrink-wrap the lug & connectors with a heat gun with red for positive, black for negative.

  (Some) fuses are held in a fuse holder that can be screwed down to the mounting board.

  A 275Amp panel switch has posts we can nut the lugs onto.

  Connect big wire stuff before screwing them onto the mounting board, or suffer from wire mis-cuts.

  Having a shunt to battery status monitor is convenient.

• Another example is the p|c connection between panels and charge controller.

  p|c: (Rover brand) 520W charge controller (Renogy). Chosen in order to handle 4 each of 100w monocrystalline solar panels in series. The CC manual recommends a fuse between the panels and the CC. Amps in series don't add so the panel set is not high in Amps but does increasing as you go from one to the next in Volts.

  "ISC" = Short Circuit Current rating is 5.21Amps from the Renogy nameplate. fudge factor that by 1.56 for fuze sizing = 8.13Amps. So he got an in-line MC4 fuse rated for 10Amps. "Slocable PV FUSE 10A 1000VDC"

  We needs a DC Circuit breaker for high voltage to disconnect solar panels. positive and negative to breaker top from panels and to breaker bottom from charge controller.

  The CC takes panel energy and sends it to the batteries.

  @CityPrepper mounted his CC on top near his inverter.

  from DC circuit breaker run to PV+ on the CC and to the PV- on the CC.

  Then CC+ ("BAT+") and CC- ("BAT-") to the positive and negative bus bars, positive is 40Amps, 8ga wire, red and black, one lug on one end, other is screwed into the CC slot.
  And a 40A fuse on the positive wire close to the CC on a fuse block. Black 8ga negative from CC to negative bus bar.

  (Different tools for the smaller wires. Measure distance, cut with a cutter, use a stripper, set lug with a crimper, (size lugs by wire and post), and shrinkwrapping it in the right color.)

  Add a Bluetooth module to the CC for remote monitoring (e.g., Rover)

  Next we add a 12V fuse block to run 12V devices. Rated wire is up to 125A coming in (1ga wire), and you could put a fuse on the feeder positive wire, but @CityPrepper used 4ga and no block fuse since he would only use 1-2 12V devices each at <1A, so long as it requires the juice to flow through a a 5A automotive fuse poked into the block one for each 12V device (positive) connection point.

  Batteries: 2 each (Renogy) 12V 100Amp-hour Lithium Iron Phosphate Self-heating batteries that can be connected in parallel (here up to 4).

  Before installing, do a multimeter voltage test on both for voltage to match before connecting. If not matching, charge each to max, or discharge completely, first.

  Attach monitor systems. Use the shelf-mode tool to activate them. Connect by cat-5 cable to monitor with separate BT-2 or with the previously-installed battery monitor on the shunt.

  Switch battery switch off, connect positives together, negatives together (in parallel).

  Put a 200A fuse on the positive battery terminal P1 before the 2-0 wire going to the bus bar.

  Connect the shunt to battery monitor with its small wire onto P1

  Observe posts require different lug sizes on opposite ends of a single wire. Fuse block has smaller, bus bar larger posts.

  Organize the cords with some strapping as you like.

  Ground your inverter and charge controller to the chassis of vehicle or grounding rod in the shed, or to the negative bus bar and from the negative bus bar to the grounding device, Green 6ga wire for grounding.

  Testing:

  KLI> Artistore LM 2020 shows the AC signal on the AC inverter and it should look good.
  • run various devices like an 1800W hair dryer or some chargers, see if any of the wires or lugs got warm with an infrared, they shouldn't.
  • Also see the CC is getting juice from the panels.
  Diagramming:
  • Draw, QTO, Purchase.
  • Draw in your 2001 Inverter, draw Red lines for Positive, postpone drawing the grounding lines until the end.
  • Perhaps starting from the inverter as a cornerstone, build out from that.
  • Label your parts, Make a Key, think through what they are, where you want to put them,
  • Figure out the wire sizes for each path, find out the post sizes before you buy the lugs,
  • Think it through before you buy stuff.
  Do your homework, hire a real consultant to at least approve your design and workmanship.

  Safety is First, so Be safe!

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