Renogy DC DC Charger w/ MPPT

[Majten]

I'm trying to work out how to best connect more than 400W of solar to my DCC50S. I'm probably going for five or six of Renogy's 100W panels, due to them being on offer, or something like three of the 175W. I'm having trouble understanding if I can actually use MC4 adapters or not for the parallel connection of the panels. I've read in several places that the MC4 can't handle the amperage of that setup, but then I e-mailed Renogy, and they recommended using the MC4's.

Could anyone give me some hints or point me in the right direction? Sorry if this isn't the place to ask.

 

[HRTKD]

I'm trying to work out how to best connect more than 400W of solar to my DCC50S. I'm probably going for five or six of Renogy's 100W panels, due to them being on offer, or something like three of the 175W. I'm having trouble understanding if I can actually use MC4 adapters or not for the parallel connection of the panels. I've read in several places that the MC4 can't handle the amperage of that setup, but then I e-mailed Renogy, and they recommended using the MC4's.

Could anyone give me some hints or point me in the right direction? Sorry if this isn't the place to ask.

Yes, you can use the MC4 connectors. However, you must put a fuse between each panel and the total amps of the paralleled panels cannot exceed the amp rating of the MC4 Y connector and the wiring. This could mean that you can only parallel four panels. I don't know what the specs are of your panels and you didn't provide the specs.

You must also stay under the 25v PV input limit of the DCC50S.

 

[Majten]

Yes, you can use the MC4 connectors. However, you must put a fuse between each panel and the total amps of the paralleled panels cannot exceed the amp rating of the MC4 Y connector and the wiring. This could mean that you can only parallel four panels. I don't know what the specs are of your panels and you didn't provide the specs.

You must also stay under the 25v PV input limit of the DCC50S.

Thanks for your reply!

I'd be using the Renogy 100W 12V, which have the following specs:

Optimum Operating Current (Imp): 5.38A
Short-Circuit Current (Isc): 5.86A

I assume I should be looking at the first number? Meaning 5 panels in parallel would give 26.9A? Judging from what I can find online, that should be within the limits for an MC4 Y connector?

 

[HRTKD]

The typical MC4 limit is 30 amps. There are some out there with more, some with less. Consequently, you have to verify the rating.

I think your five panels is close to the limit, but OK at standard test conditions. If the panels can produce more amps at low temperatures (usually we see more volts at low temps) then you could be over the limit.

You better be buying high quality wiring and connectors. Cheap Chinese knockoffs could get you in trouble.

 

[Majten]

The typical MC4 limit is 30 amps. There are some out there with more, some with less. Consequently, you have to verify the rating.

I think your five panels is close to the limit, but OK at standard test conditions. If the panels can produce more amps at low temperatures (usually we see more volts at low temps) then you could be over the limit.

You better be buying high quality wiring and connectors. Cheap Chinese knockoffs could get you in trouble.

Ok, thanks a lot for explaining! The ones I've seen have been rated at 30A. I would certainly not cheap out and buy any knockoffs, so seems like it should be fine for the warmer climates I'm planning on staying in.

 

[JayM3rch]

I have a quick question on the Dc50S I noticed most people go from Vehicle battery to House battery, Can i go from alternator instead into the Dc-Dc charger instead of the vehicle battery? i have a side post that has weird cables and i just dont have the time or desire to redo the wiring to the vehicle battery and would rather just run from the alternator to the dc-dc charger instead. will this be fine as long as its fused and obviously wired up properly?

Thank you much

 

[Steveloaf]

With 600W of solar on the sprinter roof, for the 90% of the days I'm fine (more energy than I need) I only want to charge from the alternator if I really need it (like a lot of days of clouds...), I believe that in this situation the alternator is going to be better, and the lifepo4 batteries a bit better to. Have a nice day!

I have been trying to figure this Renogy thing out. The issue of having 600watts of solar seems to be in the branch connectors being able to handle 30 amps with more than 400w of panels. You have 600 so did you do it with a combiner box? I am confused why Will wouldn't come out and say that the Renogy can be used with 660w of solar if you had a box. It was my intent to use a combiner but nobody seems to suggest it and some have asked but got no answer.

 

[dozynsleepy]

I have been trying to figure this Renogy thing out. The issue of having 600watts of solar seems to be in the branch connectors being able to handle 30 amps with more than 400w of panels. You have 600 so did you do it with a combiner box? I am confused why Will wouldn't come out and say that the Renogy can be used with 660w of solar if you had a box. It was my intent to use a combiner but nobody seems to suggest it and some have asked but got no answer.

We have 640 watts (4 x 160 watt) on our motorhome roof.

The weak link is the y branch connectors 4 way - Rated Current: 30A
We are very unlikely to see the full the 33.48 amps with the panels mounted flat on our motorohome roof (UK) so can live with this.

Each of the solar panels has a 20 amp fuse connected before the 4 port branch connector (160 watt panel Maximum Series Fuse Rating 15 A)

10AWG (6 mm2) cable connecting the 4 port branch connector to the DCC50S charge controller.

Short Circuit Current (Isc) each panel is 8.37 A so max current will be 33.48 amps

10AWG (6 mm2) cable should be good for at least 50 amps.

4 x 160 Watt 12 Volt Monocrystalline Solar Panel RNG-160D-SS-EU
1 x Solar MC4 Y Branch Connectors MFFFF + FMMMM Pair RNG-CNCT-MC4BC-EU
4 x MC4 Waterproof In-Line Fuse Holder w/ Fuse (FUSE Amp: 20A) RNG-CNCT-FUSE20-EU
1 x 15 Feet 10AWG (6 mm2) Solar Extension Cable with MC4 Female and Male RNG-EXTCB-15FT-10-UK
1 x DCC50S 12V 50A DC-DC On-Board Battery Charger with MPPT RBC50D1S-EU

RNG-160D-SS-EU
Maximum Power at STC* 160 W
Optimum Operating Voltage (Vmp) 20.2 V
Optimum Operating Current (Imp) 7.92 A
Open Circuit Voltage (Voc) 22.9 V
Short Circuit Current (Isc) 8.37 A
Cell Efficiency 21.00%
Maximum System Voltage 600 VDC UL
Maximum Series Fuse Rating 15 A

RNG-CNCT-MC4BC-UK
SOLAR Y BRANCH CONNECTORS MFFFF + FMMMM PAIR
Rated Current: 30A

 

[CI6]

If the ignition signal input (IGN) wire is wired into your fuse box using an add a fuse, on a circuit that is ONLY hot when the car is in the on position, you will not discharger your starter battery unless you are sitting parked, engine not running, with the key in the ignition on position. That would kill anyones battery. That's the same as leaving any accessory on while the car isn't running. That only applies to newer vehicles with smart alternators. I can not speak to a old school alternator setup, not using the (IGN) wire. Don't confuse ignition on with a circuit that is hot when in the accessory position. Otherwise you can't sit in your car and listen the radio while sitting in the car without the charger draining your starter battery.

How does this work if one adds a AC to DC charger - shore power, and uses it to charge the service battery per the suggestion of renogy. If you have the ign wire connected and the vehicle is off, when one connects the ac to DC charger to the service battery / alternator input, does the renogy unit detect the high voltage and starts charging the house battery, even with the ign off?

I'm trying to figure out how to add shore power to the system

 

[RandyP]

The typical MC4 limit is 30 amps. There are some out there with more, some with less. Consequently, you have to verify the rating.

I think your five panels is close to the limit, but OK at standard test conditions. If the panels can produce more amps at low temperatures (usually we see more volts at low temps) then you could be over the limit.

You better be buying high quality wiring and connectors. Cheap Chinese knockoffs could get you in trouble.

Have you a link to "better be buying high quality ... connectors."

 

[Kesa32]

How does this work if one adds a AC to DC charger - shore power, and uses it to charge the service battery per the suggestion of renogy. If you have the ign wire connected and the vehicle is off, when one connects the ac to DC charger to the service battery / alternator input, does the renogy unit detect the high voltage and starts charging the house battery, even with the ign off?

I'm trying to figure out how to add shore power to the system

Just run the ac dc to the battery separately, the Renogy just deals with solar and alternator inputs

 

[HRTKD]

Have you a link to "better be buying high quality ... connectors."

Mine came from TEMCo Industrial, so did the cable. All the lugs fit the cable they were designed for.

 

[Sgt Raven]

Mine came from TEMCo Industrial, so did the cable. All the lugs fit the cable they were designed for.

TEMco Industrial is my go to for wiring. They're a vendor on Amazon, too.

 

[dexplorer11]

Just ordered the DC-DC with mppt today and would like to know if I can use these types of wires?

 

[Hedges]

House wiring is generally good for PV, battery, and AC wiring. But for vehicles people recommend fine-stranded wire. Something to do with flexibility and vibration. For battery, due to large gauge, stiff wires, and stress on terminals, battery cable is more common. Terminated at a busbar or other component, battery wouldn't see the stress; it could have battery cables.

I don't know how important fine strands of smaller wire really is. PV wire from the panels often just has a few strands.

 

[HRTKD]

Just ordered the DC-DC with mppt today and would like to know if I can use these types of wires?

Always use a wire gauge calculator that takes into account amperage, voltage and distance. The wire insulation is assumed in most calculators. There are better options for wire than what you can get at HD. That's where I bought wire for my first install. Through this forum, I found better. The finely stranded wire that @Hedges referred to above is very easy to work with. Having to bend wire to your will to fit a tight curve is something I no long have to deal with because I'm using finely stranded welding wire.

The wire gauge calculator that I use most often:

Interactive Wire Size Calculator

Battery Chargers, Inverters, Solar Components, and Wiring Supplies for Boats, RVs, and Off-Grid Applications.

baymarinesupply.com

Note that the above calculator requires the round trip distance, not the one-way distance.

 

[Sgt Raven]

Just ordered the DC-DC with mppt today and would like to know if I can use these types of wires?

I bought 25 feet of 4 AWG red/black and copper lugs from TEMco on Amazon for my Starting battery to the controller and from the controller to my house battery. I'm using real 10AWG "solar" wire from my panels to the controller. I'm using 100% copper 10AWG red/black "zip" wire to connect my 12V devices to the Bus bars. I'm using Anderson Power Poles, 45A/10AWG, 75A/ 6AWG, & 120A/ 4AWG for my plugs.

 

[RandyP]

Just ordered the DC-DC with mppt today and would like to know if I can use these types of wires?

Use Battery cable for your higher ampacity cable:

Battery Cables - Custom Made Battery Cables

www.batterycablesusa.com

Use UV rated wire for solar panels of it is routed in the sun. Solar wire is UV rated.

 

[Sgt Raven]

Use Battery cable for your higher ampacity cable:

Battery Cables - Custom Made Battery Cables

www.batterycablesusa.com

Use UV rated wire for solar panels of it is routed in the sun. Solar wire is UV rated.

Welding or Battery cable. The flexibility helps, too.
Roger that on UV rated, too

 

[RandyP]

Welding or Battery cable. The flexibility helps, too.
Roger that on UV rated, too

You can get either battery cable or welding cable at the link I provided. Cut to length with lug installed or buy longer lengths and lugs and make your own. I went for the extra flexible 4/0 insulated with primary insulation and jacket cable to complete my battery wiring. Tight install, needed max flex cable available. The cost is good, shipping is very reasonable and products are great. Check it out, Battery Cables USA.