Victron 100/50 charge controller

[Lowcountry]

I hve a victron charge controller 100/50. I would like to wire up 4 280 watt panels. Would the best configuration be 2s2p? Also would i need to fuse the panels? Thanks in advanced

 

[HOU_Castle]

What is your battery type and voltage?

 

[Lowcountry]

12 volt 560AH lifep04.
I currently have 2 315 watt panels in series using that controller but got the 280 watt panels at a great deal including the racking.
So I'll remove the other panels all together and use then elsewhere.

 

[HOU_Castle]

12 volt 560AH lifep04.
I currently have 2 315 watt panels in series using that controller but got the 280 watt panels at a great deal including the racking.
So I'll remove the other panels all together and use then elsewhere.

MPPT 100/50. Rough calculation for 4 panels @ 280W: 4*280/12.5= 89.6A. Your MPPT 100/50 limit is 50A; it's over 39.6A. Not good.
Current 2 panels - 315W: 2*315/12.5= 50.4A, your MPPT 100/50 limit is 50A. Very close, but ok.

 

[Lowcountry]

Ok, thanks. Guess it time for a bigger charge controller.

 

[HOU_Castle]

If you know that 4 panels of 280W is your max, then you can buy same mppt 100/50. Its cheaper. Or upgrade you battery to 24V.

 

[Lowcountry]

I was just thinking adding another 100/50. I have a Victron 100/30 controller also. 280x2=560÷12.5=44.8.
Do you think that too much over paneled?

 

[HOU_Castle]

I was just thinking adding another 100/50. I have a Victron 100/30 controller also. 280x2=560÷12.5=44.8.
Do you think that too much over paneled?

The risk is you will burn your mppt 100/30 in the long run. If this setup is for temp, then the risk is lower. My recommendation is to buy another mppt 100/50. And keep your mppt 100/30 for back-up (in case one of your 100/50 fails, you can use it for temp. till you get your replacement).

 

[Lowcountry]

Ok, thanks for the help, much appreciated!

 

[rmaddy]

It doesn't hurt an MPPT SCC to be over paneled with extra wattage. The important specs are the SCC's max PV input voltage based on the temperature adjusted Voc of the panel array and the max short circuit current. Victron lists the latter on the data sheet.

You should also use the battery charge voltage (probably about 14.4V) in your calculations instead of 12.5V.

So a 50A SCC can make use of up to 720W (50A x 14.4V) of solar panels. The 1120W (4 x 280W) you plan to use will work just fine. That over paneling won't hurt anything. The only issue is that you can't take full advantage of the wattage midday. But the over paneling will give you more power earlier and later in the day and in the winter.

 

[HOU_Castle]

Ok, thanks for the help, much appreciated!

You may want to ask the forum having 2 mppt 100/50 charging same battery will cause any mppt logic confusion. I have not tried it yet. It should work. But just to be sure before buying another mppt 100/50.

 

[rmaddy]

You may want to ask the forum having 2 mppt 100/50 charging same battery will cause any mppt logic confusion. I have not tried it yet. It should work. But just to be sure before buying another mppt 100/50.

Two Victron SCCs can be setup to communicate with each other and coordinate their charging efforts. The biggest potential issue is can the batteries handle up to 100A of total charge current?

 

[Lowcountry]

With the battery shunt I have wired to the battery and withe the 315x2 panels and victron 100/50 controller I usually see around 30 amps going in the battery during charging, never saw 50 Amps but probably due to heat(south Carolina) and panel angle.

Now the question is what do I need to do to fuse it? The panels in series don't need fuses correct? But what about when I put them in parallel?

 

[rmaddy]

withe the 315x2 panels and victron 100/50 controller I usually see around 30 amps going in the battery during charging

30A x 14.4V = 432W out of 630W of panels. That's 68%. High heat and poor angle will do that.

Now the question is what do I need to do to fuse it? The panels in series don't need fuses correct? But what about when I put them in parallel?

Once you have 3 or more strings of panels in parallel you need to fuse each string. If you only have 2 strings in parallel then you do not need to fuse them.

In either case you should add a PV disconnect near the SCC.

 

[Lowcountry]

Thanks, I do have a breaker for the solar disconnect, thanks for the help rmaddy