Questions about your YouTube Video recommendations?

[aus10sha]

Im setting up an offgrid system for a remote cabin in CO. Basically to run lights, music, charge phones, small fan, etc. No really heavy loads.

In your videos you say to connect positive lead from charge controller directly to the inverter, not to the battery first. This leaves the possibility of the main breaker tripping and isolating the controller from the battery. This allows current to flow from the panels to the controller with no battery connected? Is there a reason for this or is this an oversight? It seems like the positive from controller should connect to battery side of main breaker with the inverter and DC fuse block on the load side, correct?

Secondly, You say not to use the DC load connections from the charge controller? You "just dont like them". Why? It seems that you lose the advantages of the controller. The controller should protect overdischarge from the DC fuse block. I see that the loads drawn from the inverter may be too much for the controller but the DC block should be relatively low loads. Running the load directly from the battery may ruin some expensive batteries.

Thanks, I do really enjoy your videos. I also noted that several others have the same questions but havent been able to find the answers. Cheers

 

[gnubie]

The DC load output on most charge controllers is fiarly low current, maybe 5 amps. Victron controllers, and a couple of other good brands, can actually put out a substantial amount of amps on that connector. Check the specs for your controller's switched output. If it can't carry the current you want to draw you will have to go direct across the battery.

You can still use the low voltage cuttoff or time controlled feature of the controller to manage your load. In this configuration you would use the controller's output to control a relay and that relay would then switch your load.

 

[aus10sha]

That makes sense. Thanks!

Any thoughts on the first question?

 

[gnubie]

I haven't seen the video so can't really comment beyond saying perhaps the intent was to get as much current to the inverter from the controller as possible, ie instead of the battery being the hub of connections the inverter was.

 

[TCgreg]

I am confused by "connect the positive lead from the charge controller directly to the inverter" Not sure the video you are referring to but both positive and negative leads from the solar charge controller should be attached to the battery through a fuse or circuit breaker. The inverter should also be connected to the battery. I haven't seen a system where the solar charger is connected to the inverter.

You should always connect the solar charger to the battery first before connecting it to the solar panels. That turns it on and regulates the voltage within the unit.

Check with the manufacturer for the load terminals on the solar charge controller. Often they have a low amperage rating. Personally I like to make the battery the genesis for all loads and use a shunt based battery monitor attached to the negative side of the battery that measures all current in and and out which will give you an accurate battery state of charge. IMO forget the load terminals on the solar charge controller.

 

[Rider]

In your videos you say to connect positive lead from charge controller directly to the inverter, not to the battery first.

I don't believe that has ever been said. In every design I've ever seen, a pair of wires runs from the solar charger to the battery, sized for the max current of the controller. A second set of wires is run from the battery to the inverter, sized for the max current of the inverter. I don't ever remember seeing a design that ran a wire directly from the solar charger to the inverter. Turning on the inverter would most likely ruin the charge controller.

 

[aus10sha]

Check out the wiring here:

DIY 400 Watt 12 volt Solar Power

I agree it doesnt seem right. Thats my question

 

[TCgreg]

So, in the video Will is using the inverters clamping bars as common busbars for the battery and solar charger. The battery is attached to the inverter as it should be and the solar charger is also attached to the inverters clamp bar. This method will work fine. I prefer stand alone busbars for clarity of wiring but in the end electricity don't care.

 

[MrNatural22]

This issue was discussed in length on the old forum concerning CC protection should the breaker trip from the battery leaving power continuing to flow from panels onto the CC (not good).
I’m going to hopefully avoid that problem by running a separate independent wire from the positive battery side of the breaker to the positive of the CC keeping power continuing should the breaker trip. Makes sense and shouldn’t be a problem. This also allows the power from the CC to still be connected directly to the inverter for optimum solar panel power to the inverter. Relays were talked about in the original post but sound more involved to do the same thing.
Any input on this simple solution??

 

[b.james]

Yes I use the inverter terminals as bus bars going to the battery and connect the charger to them . If there is a fuse in that line anywhere and it blows it will leave the PV connected without the battery.
I don't put a fuse in there because the inverter has its own fuse inside and the controller generally too but not always . It should be checked . When one of those add in fuses blows 100 times its burn current can flow for 10ms or so and 10 times its burn out current for half a second . So personally I don't use them there.

 

[aus10sha]

This is all what I thought Just wanted to make sure before I burned up our cabin.

Thanks all

 

[Will Prowse]

Im setting up an offgrid system for a remote cabin in CO. Basically to run lights, music, charge phones, small fan, etc. No really heavy loads.

In your videos you say to connect positive lead from charge controller directly to the inverter, not to the battery first. This leaves the possibility of the main breaker tripping and isolating the controller from the battery. This allows current to flow from the panels to the controller with no battery connected? Is there a reason for this or is this an oversight? It seems like the positive from controller should connect to battery side of main breaker with the inverter and DC fuse block on the load side, correct?

Secondly, You say not to use the DC load connections from the charge controller? You "just dont like them". Why? It seems that you lose the advantages of the controller. The controller should protect overdischarge from the DC fuse block. I see that the loads drawn from the inverter may be too much for the controller but the DC block should be relatively low loads. Running the load directly from the battery may ruin some expensive batteries.

Thanks, I do really enjoy your videos. I also noted that several others have the same questions but havent been able to find the answers. Cheers

SCC will not push current until it senses a voltage. If the main breaker on the battery trips, the SCC has no reference voltage, so current stops flowing. It is how the charge profile algorithm works. But yes, if the main fuse trips and the SCC is connected to panels only, it can burn out.

But if your main fuse tripped, you have MUCH larger problems to worry about. I don't mind the SCC burning out if I know the batteries will be good to go. If your main fuse is tripping, something is not calculated properly. That is a last resort safety layer on a system.

And yeah as the other people just said, the electricity doesn't care. If your wire gauge size is correct, you can connect any component wherever you wish. Bus bars do make things look nice though. If you have a lot of components, use some nice beautiful bus bars. If you have 3 components and 2 require much smaller wires than the other ones, connect them to the big one, like an inverter. Just make sure every wire is the proper size.

The SCC wires are voltage sensing, so best to have them over-gauged.

I hate the DC load connections on SCC because the internal OCPD always trips for the silliest reasons. It will be a 5 amp load on a 20 amp load terminal and it will trip for no reason. I hate them. Seems pervasive in these units.

 

[Will Prowse]

Keep in mind that the OCPD needs to protect the device AND the wire. Usually it is best to size the wire first, then size the fuse to the wire and appliance.

SCC are dead simple converter circuits. Sure the power point tracking can seem advanced, but at the end of the day its just a converter circuit. And we are connecting to a battery, not some type of noisy power supply or something. Just make sure the wire gauge size is proper for voltage sensing and the rated current, and you are set

 

[aus10sha]

From the Man himself! Thanks so much. That all makes sense.