PV system wiring diagram

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PV system wiring diagram

Postby mountainman » Wed Mar 11, 2015 2:06 pm

Here is a professionally drawn :D PV system wiring diagram. It shows more parts than absolutely necessary. The simplest PV set-up requires only four parts (which are starred) plus a load:

- PV panel
- charge controller
- fuse
- battery

The meters are not necessary but it's convenient to be able to see the status of the system at a glance. The current meter shows positive current charging the battery bank and negative current discharging the battery bank.

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Re: PV system wiring diagram

Postby WorldWeary » Fri Mar 13, 2015 10:40 pm

Just saw this. Mountainman...you're a saint. I would literally frame this and put it on my wall. It's immensely helpful. THANK YOU!
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Re: PV system wiring diagram

Postby mongolking » Fri Mar 13, 2015 11:14 pm

It's a revelation to me. I know very little about electronics. Seeing the inverter wired in parallel with the appliances isn't something I would have thought of.

The function of the shunt remains a bit of a mystery.
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Re: PV system wiring diagram

Postby Phathack » Fri Mar 13, 2015 11:56 pm

mongolking wrote:It's a revelation to me. I know very little about electronics. Seeing the inverter wired in parallel with the appliances isn't something I would have thought of.

The function of the shunt remains a bit of a mystery.


Note there is no Power Inverter, 12VDC to 110VAC, in the circuit, all "Appliances" are 12VDC devices.

The Shunt is part of the DC Current meter. The Shunt is either Internal to the meter of External if the meter is to be located some distance from the power source.
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Re: PV system wiring diagram

Postby mongolking » Fri Mar 13, 2015 11:59 pm

Phathack wrote:
mongolking wrote:It's a revelation to me. I know very little about electronics. Seeing the inverter wired in parallel with the appliances isn't something I would have thought of.

The function of the shunt remains a bit of a mystery.


Note there is no Power Inverter, 12VDC to 110VAC, in the circuit, all "Appliances" are 12VDC devices.

The Shunt is part of the DC Current meter. The Shunt is either Internal to the meter of External if the meter is to be located some distance from the power source.


Brilliant! Thanks.
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Re: PV system wiring diagram

Postby Phathack » Sat Mar 14, 2015 12:19 am

Phathack wrote:
mongolking wrote:It's a revelation to me. I know very little about electronics. Seeing the inverter wired in parallel with the appliances isn't something I would have thought of.

The function of the shunt remains a bit of a mystery.


Note there is no Power Inverter, 12VDC to 110VAC, in the circuit, all "Appliances" are 12VDC devices.

The Shunt is part of the DC Current meter. The Shunt is either Internal to the meter of External if the meter is to be located some distance from the power source.


Note that if you are outside of North America that Inverter is 12DC to 220VAC, but then you already know that... :lol:
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Re: PV system wiring diagram

Postby mountainman » Sat Mar 14, 2015 2:42 pm

Thank you Phathack for preventing untold numbers of aspiring off-the-grid MGTOW from frying their systems by trying to put AC and DC on the same circuit based on my diagram. I"d have felt bad if that happened.

To be clear, all the devices on the left, including the inverter, are 12 volts DC. The inverter's AC outputs aren't shown.
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Re: PV system wiring diagram

Postby toolate » Thu Dec 17, 2015 10:06 pm

Just happened upon this. Are the blocking diodes in the controllers to prevent reverse current situations?

I've seen some larger systems with these installed separate, possibly as a backup?

I just happened upon a 50 watt panel and controller and hope to experiment with it on a remote radio repeater site. We'll see what it can do this winter.
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Re: PV system wiring diagram

Postby mountainman » Fri Dec 18, 2015 11:07 am

Most charge controllers have some kind of built-in mechanism to prevent reverse current, usually by disconnecting the PV array from the battery bank entirely. A blocking diode is effective but not very efficient because it drops the voltage by a fraction of a volt, a few percentage points of power at 12 volts.

My system has two charge sources wired in: An AC battery charger and a DC-DC converter that converts the high voltage of my unusually-wired PV array to 12 volts. The DC-DC converter draws power from the battery bank when there's no sun so I had to install a blocking diode and heat sink and take the efficiency hit.
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Re: PV system wiring diagram

Postby mountainman » Mon Jan 09, 2017 2:52 pm

Saturday I wired up a simple PV system for a friend who's making a camper van. A picture of the result is attached.

Electricity flows from right to left. There are three charging sources connected to the charge positive and negative terminals on the right:

- PV charge controller
- AC battery charger
- Van engine alternator

The charge wiring is 10ga so there's a 30 amp fuse connected to the upper charge plus terminal. A current shunt is attached to the lower charge minus terminal. The other end of the fuse is connected to a hefty knife switch. The knife switch positive and the current shunt negative are then connected to the battery bank as the source of charge. The battery bank is two 12 volt 110 amp-hour AGM batteries wired in parallel.

The load wiring is a mirror image of the charge wiring. Two (black) wires from the battery bank go to a second knife switch positive and current shunt negative. The knife switch is connected to another 30 amp fuse. The fuse and current shunt are connected to the load positive and negative terminals on the left. The AC inverter is connected to the load terminals.

There is some 10 gauge wiring in the load section so the fuse is again 30 amps. The rest of the load wiring is 4 gauge. If the 10 gauge bits were replaced with 4 gauge then the fuse could be increased to 100 amps.

The current shunts are wired (blue CAT5 cable) to a pair of combo volts/amps/watts/KWH meters (off-image) to indicate how each half of the circuit is operating. The charge and load sections are completely independent so that if one half isn't working for whatever reason the other half isn't affected.

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