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Solar Panels....

Discussion in 'Ham Radio Discussions' started by KB4MNG, Jun 23, 2019.

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  1. KF7YED

    KF7YED Ham Member QRZ Page

    Hm. Nope. Not understanding any of that.
     
  2. KK6NOH

    KK6NOH Ham Member QRZ Page

    That consumes gasoline, time, and wear and tear on the vehicle. Not to mention that assumes you have to drive every day.

    Solar still seems the better choice.
     
  3. KF5LJW

    KF5LJW Ham Member QRZ Page

    It is common practice, keeps batteries topped off and saturated while driving, and gives you insurance for those times you parked with cloudy days and runs down the batteries. With solar you are SOL and go dark. Or start your engine and recharge the batteries. It will make your batteries last longer. Your alternator can handle it.
     
  4. KK6NOH

    KK6NOH Ham Member QRZ Page

    I have a solar panel in my car to keep my car battery topped off and fresh, so it lasts as long as possible. The car gets driven about once a week, sometimes once every two weeks.
     
  5. KF7YED

    KF7YED Ham Member QRZ Page

    So your diagram looks like there's nothing but a fuse between the solar panel/battery and the load. I'll keep looking elsewhere. Too many conversations going on here......
     
  6. KK6NOH

    KK6NOH Ham Member QRZ Page

    If you aren't sure what some of the symbols are on that schematic, I would be happy to help explain.
     
  7. KF5LJW

    KF5LJW Ham Member QRZ Page

    What is the problem? It is a simple DC wiring schematic. Likely not exactly what you require in terms of power and current demands, but only thing that changes is wire and fuse sizes. Everything to the right of the batteries is LOAD. 1st drawing just shows an Inverter as the only Load. Pretty straight forward connected directly to Battery Term Pose and fed with a fuse.

    Second drawing is showing multiple Loads with Distribution to various load devices like an Inverter, Microwave Oven, House Lights, or a gizmo.

    Here is the biggest take away you should come away with: The Dual Fuse Block on the Battery Terminal. One fuse facing Charge Controller, and the other fuse facing the LOAD. The Load Fuse is how you interconnect the battery to House Wiring. Here is the best piece of hardware all solar uses should know about and use. It provides the best protection you can get since there are non-protected lead wire to battery term post. It bolts directly to Battery Term Post. Made by Blue Sea systems. They also have the distribution blocks for branch circuits. What you see below is both single and dual MRBF fuse links.

    [​IMG]
     
  8. KF7YED

    KF7YED Ham Member QRZ Page

    Yes, that's what I'm saying. The panel is connected to the charge controller terminals marked "Panel" and the battery is connected to the terminals marked "Batt." That leaves the wires from the camper (LOAD) to connect to the battery. But to me that means they're also connected to the charge controller output marked "Batt" so I was thinking there should be something in between. So you're saying the fuse is what goes in between. That answers my question. I like the dual link so I can have a fused link on both lines-- one to the load and one to the charge controller. Got it.
     
  9. KF5LJW

    KF5LJW Ham Member QRZ Page

    You got it, but electrically The Batt Out on Charge Controller and battery terminals are not the same point. As you have observed there is a Fuse between them. Biggest mistake DIY's make is install fuses between the panels and controller, and or install fuses on the Batt Out of the Charge Controller to battery. Huge difference putting the Controller fuse at the Controller output vs on the battery term post. .

    Solar Panels are Current Sources, not Voltage Sources like a battery. You can shout out your panels all day long, and nothing bad hap[pens other than no power. Look at any panel spec and you will see a/ Spec called Isc (current short circuit.) Means just what it sounds like, the maximum current the panels can theoretically generate. On a 100 watt battery panel will be around 6 to 7 amps. No way is 6 to 7 amps going to burn up 14 AWG panel wire, thus no fuses required if limiting panel parallel string to 2 or less..

    The battery is a different story and is a Voltage Source and can supply hundreds to thousands of amps of current when shorted out. Fuses are for one purpose only, to protect wire from over current. You put the fuses on the power source which is the battery, not the panels. The dual fuses protect the two wires on the Battery Term Post, 1 to Controller, and 1 to load. Note fuse and wire size are different. Larger fuse requires larger wire.

    So in your case with a 100 watt panel only requires a 10-amp controller which 14 AWG is likely large enough between controller and battery with a 10-amp fuse. But let's say your load is a 1000 watt Inverter will require 4 AWG and a 100 Amp Fuse from the battery.

    Now go back to the diagram and it should make sense to you now.
     

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