Four 100W panels, 40A CC can charge li, 1000w pure

[TedNeedsHelp]

Hi, I want to add two 100w panels to my existing two 100w panels so total four 100w panels together. The wires are prob a good 40 feet to the 40a cc (can charge li). (currently I am using a 20a cc but I have the 40a cc) two 100ah li battery, and 1,000 w pure sine inverter. I just have a few questions. Should I use two branch connectors and connect two panels in series or just use mc4 1-4 branch connectors. I do not have a fuse on the 40 feet wire from panels to CC. Any advice is appreciated. thank you in advance. Should I do anything else to improve this setup?

 

[gnubie]

What's your battery bank voltage? Are you using a MPPT charger or a PWM charger? What's the gauge of the existing wiring back to the charger and is it being replaced or kept for use with the upgrade?

 

[TedNeedsHelp]

I actually don't have the li battery yet. But I do have the 40a cc mppt li. I have the two additional 100w panels. Total is 400w. I have 10 awg wire. I want to keep the 10 awg wire. I'm hoping there will be a black Friday sale for the li battery.

 

[TedNeedsHelp]

I actually don't have the li battery yet. But I do have the 40a cc mppt li. I have the two additional 100w panels. Total is 400w. I have 10 awg wire. I want to keep the 10 awg wire. I'm hoping there will be a black Friday sale for the li battery.

I actually just bought the 40a rover li and just read in this forum about people's complaints. I hope I didn't make a mistake by buying it. Please somebody tell me it will be ?

 

[gnubie]

It's always possible he had a faulty unit, the two I have work well enough. They are connected to about 1kW arrays each and reliably wake up in the morning and properly charge their respective batteries. One has charges lead acid, the other lithium. They are a bit inaccurate when it comes to battery voltage, it's a common enough theme in the cheaper end of the market, but you can compensate by adjusting the voltages the charger is set at for float and absorption. If you want to do anything more than basic configuration you will need bluetooth comms to a smartphone with their app, or a Windows PC connected to the serial port on the charger, or their remote panel. The port can be RS232 (proper RS232, swings +/- so you need a proper RS232 port for the PC not a TTL port) or RS485.

I'm guessing you have 12V class panels, so Vmp probably around 18V, Imp 5.5A. If your plan is to connect two panels in series then parallel those sets and then run back to the controller via the 10 AWG wiring you will be looking at around 11A maximum over the wire. The voltage drop at full power is minimal and nothing to worry about. 2 panels in series is better for a MPPT controller so unless you have shading issues that is how I would do things.

2 in series is preferable for MPPT unless you are trying to work around shading issues. If you plan on configuring the batteries for 24V you have no choice but to use 2 or more panels in series.

The Rover 40A li can handle up to 100VDC on the solar input. If you don't have low temperatures there you may just be able to sneak in putting them all in series too. That's no good for shading of course. If you want to look into this post the specs for your panels, the label on the back or the web site will do.

 

[TedNeedsHelp]

Can you tell me how the mc4 1-4 branch connectors will work?

 

[TedNeedsHelp]

Right now I have two 100w panels connected with y branch connectors and sometimes I'll get 10-11 amps. So if I series the four 100w panels I'll still get 10amps?

 

[gnubie]

If you configure them as 2s2p, yes as strange as that might seem. When you put 2 panels in series the voltage goes up but the current remains the same as a single panel, combine two of those sets in parallel and you are back up to 10-11A but at roughly twice the voltage. Watts = volts x amps so you still get access to the additional power from the 2 new panels.

When purchasing the new panels try to get panels with similar voltage ratings as the existing ones if you decide on 2s2p. If you are doing all in series the amps is the important part to keep similar as the lowest amp rated panel sets the standard for all the others in series. The voltage is not as important but you still need to live within the restrictions of your solar charger.

If you post the existing specs and the specs of the panels you are considering buying someone can let you know if they are a good match.

 

[TedNeedsHelp]

Do I need to put a fuse on the 40feet wire?

 

[gnubie]

From a technical point of view 2s2p or all series of those panels can't provide more current than your controller is rated for so it isn't needed. Given that your controller can handle full current and the cabling can too, there's not a fuse that can provide any protection but not also nuisance blow.

Check your local regulations, if they say fuse, then fuse.

 

[TedNeedsHelp]

I kind of want to use the mc4 1-4 branch connectors because the wires are longer and it will allow me to configure the panels a little bit better. If I do that I will get 20amps? Will my setup be ok?

 

[gnubie]

If you put all 4 panels in parallel you can only set up your new batteries for 12V as you won't have the voltage from the array to allow you to charge them if you set up for 24V. Of course your inverter will also dictate what voltage you need to work with and since you haven't answered any of the questions regarding your battery side voltage ... who knows.

Your array might be too close to battery voltage for it to be reasonable to use a MPPT controller with 4p but since you haven't posted any information about your panels either again ... who knows.

Your 10 AWG wiring will cope with the approx 25A peak 4p will provide but again, no information about the panel so this is merely a guess as to what your panels are, 12V class, approx 5.5A Imp.

Best practice says that when you use more than 3 items in parallel you should have fuses between each item and the common + wire. Maximum series fuse will be shown on the label on the panel, typically.

 

[TedNeedsHelp]

I want to keep my batteries at 12v

 

[TedNeedsHelp]

I also have two 100w renogy panels

 

[gnubie]

Those HQST panels in parallel will work with a MPPT controller charging a 12V battery but depending on the temperature you may find their power output is limited as the battery voltage rises and the temperature causes the panel's voltage to fall.

There are different model Renogy 100W panels, you'd need to provide the information for them or link to the specific model.

 

[TedNeedsHelp]

i don't want to go up to the roof and take a picture of the renogy panels but they are 100w Monocrystalline panels. I guess you are trying to tell me that the 2s2p will be the better options than using the mc4 1-4.