solar panel old and new connection

[wren]

I am new to this forum and haven't figured out how to thank somebody for their response. My first question was about battery connections to an inverter. THank you Michael for your generous response and time.
This one is in regards to solar panel connection.
I bought two 400 watt, 24 volt panels which I will run in parallel. I have two 8 year old panels, 180 watts each 12 volt. Is it ok to connect those in series and then connect them in parallel with the two new ones, as to getting 1060 watts 24 volt together?
If that works, I would need a fuse going to the charge controller, which is 50 Amps, as the panels together produce 44Amps. Is that correct? The charge controller is 80Amps, or is the fuse 80 Amps?
Is that an inline fuse or a breaker, close to the panels or close to the charge controller?
Thanks in advance to the person who might be able to respond to this question.
The size of the cable needs to be 6 or 4 from panels to charge controller?

 

[Rednecktek]

In short, no. If you look at the back there should be a label with all sorts of weird numbers. One of those is VoC or "Voltage Open Circuit" which is a very important number.

Imagine, if you will, what would happen if you took a 12v car battery and clipped some wires to it. Now take the other end of those wires and plug them into the outlet on your wall. See all that magic orange smoke and fire and dirty looks from the wife?

Now, imagine if you took a panel trying to produce 40v and plugged it into a panel trying to produce 18v? Same basic concept, smoke, fire, angry wife.

What you would want to do is set up 2 complete charging circuits on MPPT controllers. One set is 400w in series -> MPPT -> battery and the other set would be something like 4s2p 100w panels (4 panels in a series string, another 4 panels in a series string, the two "strings" paralleled) -> 2nd MPPT -> battery.

Now, on your MPPT controller it'll have a rating of what its max PV voltage in is, make sure the panel strings don't exceed that or smoke, fire, angry wife.

If you post the info from those panels we can double check your work.

As to the amperage question, the 80a it's talking about is how much amperage it can send to the batteries, so your fuse between the MPPT and the batteries would be 100a (80*1.2=96, but nobody sells a 96a fuse). The amperage from your panels is going to be based on that data info and how you have them connected. That will be a breaker or fuse (both have their pro's and con's) between the output of your charge controller and your battery.

It would also be helpful to know what kind of load you're planning and what size inverter you're looking at. Hopefully this is a start.

 

[dehv]

Second that vote for 2 controllers, one for old one for new panels.

 

[Hedges]

I'm a contrarian. I would do it. (or maybe I just like to argue.)

You'll have 3 PV strings feeding SCC, so each string should have a fuse of the value shown on panel label.
What is Voc rating of each panel? If the "24V" panel has Voc and Vmp close to 2x what "12V" panel ratings are, it will work fine.

I would orient one 400W panel SE with suitable tilt (straight at the sun at 9:00 or 10:00 AM), one SW, tilted for 3:00 or 4:00 PM sun, and the series string 2x 180W due South aimed at Noon or 1:00 PM sun. (the 1-hour range depends on whether you do this before or after daylight savings time ends.)
Unless you have morning fog, or shadows.

Multiple angles reduces peak power, extends hours of production.

400 + 400 + 180 + 180 = 1160W (STC) if all oriented at sun.
1160W/24V = 48A, add 25% need 60A fuse to battery and suitable wire gauge. The multiple angles would reduce this a bit.

Assuming a 24V battery. But, 24V panel may not have enough voltage headroom for MPPT controller into 24V battery.
Data sheet for charge controller?
Full specs for panels? May need more panels in series, higher voltage, to make this work well.