Another small newb project.

[littleharbor]

So Isc. should be no more than 25.28. Chances whatever you are measuring with isn't too accurate.

[Sunking]

Also the 28.2a is pushing my CC to its limits of 30a, so realistically I can't add anymore panels, which I was planning on adding 2 more

Assuming the controller is MPPT you are maxed out already, and if you have a MPPT controller your panels are configured incorrectly with 4 in parallel. You would want 2s2p.

400 watts of panels on a 12 volt battery with MPPT Controller requires 30 amps. If you used 24 volts can go up to 800 watts.

And now I'm up to an hour just on batteries and it's at 12.08, so was the problem the whole time in the wiring?

Told you that was the most likely problem a long time ago sounded like a poor wiring job. Where are you measuring voltage and how? There are 2 points to measure and it must be done correctly/

1. Directly on the Battery Term Post
2. Directly at the Inverter Input Terminals.

What you should see if the battery is good is very little voltage sag. Assuming that is good, you measure at the Inverter Input terminals. If the wire is large enough, not to long, and good termination you wil not see much voltage loaas. There should be no more than .1 volt difference at full power.

Ok, after an hour of running the bank didn't drop below 12.08 I hook my CC back up and it's holding at 12.14 with an overcast sky. So does that seem right and there was just an issue with my connections the first go around?
#2- Under load it's showing 12.3v and 16.9a. From panels, as the sun peaks out occasionally those numbers jump up a bit.

Yep poor wiring. Its all on you. If your controller is MPPT, rewire your panels. 2 in series in parallel with 2 in series (2S2P). What make and model is your controller?

If your controller is PWM, you must wire all the panels in parallel and if it is PWM turns your 400 watt panels into 275 watts.

[Sunking]

I understand this is not the tv for offgrid, I am not offgrid. I am simply starting to learn about solar and stand alone battery bank systems. Practicing and building my skill set for when I finally get my property out in the woods,

Allow me to steepen your learning curve as it is the most important lesson you need to learn real damn fast before you regret your choices. It is a real easy lesson to grab but vitally important you fully understand. It is simple money math a 5th grader can understand.

Anything you take off grid is going to cost you 5 to 10 times more than buying it from the power company the rest of your life in battery replacement cost alone. You will also have a new part time job 365 days a year with no days off worrying about and monitoring your system Abuse your batteries and they are toast and that drives up the cost even more than 5 to 10 times.

A new set (pair) of Trojan T-105 Batteries cost $280 to $320 dollars brand new. A few short years from now when they are boat anchors will have provided you with roughly $30 to $60 worth of electricity bought from the POCO. So be careful what you ask for.

2nd thing you need to know. 12 volts is for toys like RV's and boats. 12 volts has no place in home or cabin. Too expensive and dangerous with very limited power. Example an $700 80 Amp MPPT Controller and only input so much power based on battery voltage as follows.

1000 watts @ 12 volts
2000 watts @ 24 volts
4000 watts @ 48 volts
8000 watts @ 96 volts.

You would be a fool running anything more than 500 watts @ 12 volts. One more hint. Your Inverter should be equal or less than panel wattage.

3rd lesson I hope you do not have to learn the hard way because you have already flirted with disaster, death and destruction. Loose connections and poor wiring habits will get you killed. The lower the voltage you use, the greater the chances you will burn your home down. Just one loose or poor connection is al it takes. If you are lucky this will be the extent of your damage.





Not so lucky and you get this. You you might not get to see the FD Investigation pictures because you died in the fire as a result of just one bad connection.

[uscgsapper1]

My CC is PMW, it's a 30a 12v. My panels are all in parallel right now, I was thinking at this point my system is about maxed out. All my wires are minimal length and large enough gauge, my next investment is going to be a MPPT controller @ 24v and switching my whole system to 24v. I understand it all cost more than buying from the grid, this is just education for me. Once I have enough knowledge and purchase my offgrid property my goal is to set up a 48v system with a significant array, I am extremely cautious when wiring things up, I believe I simply didn't have a connection tight enough. But as the whole thing stands right now, it is functioning I believe as should. I know I am asking a lot from it but that's how I am I usually push the envelope with just about everything in my life, but always with a reasonable level respect for what I'm working with. I feel at this point my system is maxed out and what I'm asking of it is probably a little to much, I will lower my expectations a bit until I change my system to 24v and expand it. I will keep on here as things change and I invest more money and my scope of knowledge grows with this subject, thanks for all the input and experience from everyone helping to iron out the kinks and fill in the gaps!
Random thought; can you get to a point where your system can run a reasonably draw and still charging bank in an effluent way to watch tv for 6-8hr and know the batteries will be topped off before sundown. For a few led light for the evening.

[Sunking]

My CC is PMW, it's a 30a 12v.

That was a huge mistake. OK if your controller is PWM you are forced to use extremely expensive Battery panels vs Grid Tied panel at 1/2 to 1/3 the cost. Forced to wire all your panels in parallel requiring fuses, combiners, and a lot more and larger wire. That is costing you 300 to 400% more than you had to pay. Only good news with the PWM controller is you can add 2 more of those expensive panel for a total of 600 watts, but you only get 400 watts out.

Random thought; can you get to a point where your system can run a reasonably draw and still charging bank in an effluent way to watch tv for 6-8hr and know the batteries will be topped off before sundown. For a few led light for the evening.

Absolutely as that is the goal of any system. The very first step in a proper design is to determine how many watt hours you use in a day, and how many Sun hours you have in December and January. Once you know those two things everything falls in place.That is how you determine everything, panel wattage, battery capacity, and controller.

99% of folks who come here do it backwards. They buy something and come here to find out what is wrong and why their battery is dead. Answer is alway the same, same answer you got. It is called deficit charging, which means you use more in a day the panels can generate.

Think of it this way. You have $100 and open a bank account with an ATM card. You spend $30 a day and your job only pays you $10.Come day 10 you are bankrupt and your ATM card is worthless. Difference is with physics there is no living beyond you means, credit, loans, or compassion. Like death there is no turning back, your done on earth. .

[uscgsapper1]

I understand the math, so you believe I can safely add 2 more 100w panels? Or should I just stop where I'm at and rethink the whole set up, instead of buying 2 more panels just start investing and building a whole new setup?

[LETitROLL]

I understand the math, so you believe I can safely add 2 more 100w panels? Or should I just stop where I'm at and rethink the whole set up, instead of buying 2 more panels just start investing and building a whole new setup?

I started with a 100w panel, and after learning the math, and the supply and demand of products in the market place it does not make much sense to use many of them, 1 or 2 for a rv or camping situation is kind of what they are fine for. I sold mine slightly used for 95% of what i paid new and put the money towards 2 large panels. I got the larger panels for nearly the same price per panel as the 100w and they have double the output and less mounting and wiring for the system that way as others have mentioned. I'm sure you would not regret upgrading to a better designed system, and you should be able to get some of your money back on the 100's, (they are popular), otherwise you could run a split system and keep what you have plus start getting better stuff as available, and run some of your loads off one, and some off the other, then when something fails or breaks you are not dead in the water and can still run a light and radio.

[uscgsapper1]

Ok so I added 2 more panels, so I have 600w 12v panels and 2xTrojan T-105 and the system is doin MUCH better. But I think I'm at the max with my PMW 30a controller, I'm already thinking what's next. I want to change the system to 24v, is it ok to mixed 12v panels in series for 24v with a 24v panel in parallel is my first question?