I need help with solar system and charge controller.

[fixit1]

I looked for a similar thread and didn't find an answer. Here is my situation. About 15 years ago I bought an acre of undeveloped land and built a "cabin". The power company wants $63,000 to bring power in. Back then I used it for snowmobiling and hunting so I brought a old used solar system up. 12v Trace inverter (220v), approximately 700w of mixed solar panels, a 1000watt wind generator, an unbranded charge controller, and 6 rv batteries (12v). The charge controller is wired to a 12v 100 amp water heater "dump". The system was adequate at the time, but I seldom had power in the mornings (battery voltage being below 9.5v).

I began going through batteries, they lasted around 12 months. I installed a diode at the wind generator but it didn't help the battery voltage. My charge controller isn't wired like most, the solar/wind generator goes directly to the batteries and the controller dumps at 15 volts down to 12.6. I can't adjust the end dump voltage, its fixed at 12.6. I've never liked that, it seems to deep cycle the batteries.

In the meantime I've divorced and retired to the cabin (2.5 years ago). Recently I purchased 4 24v solar panels and replaced 4 12v panels that were only putting out around 10v. This was a game changer for power during the day, doing laundry is not an issue (no generator required). I had read that a MPPT charge controller would accommodate the 24v panels.

I bought a 100amp MPPT charge controller off of ebay but it will not stay on 12v with the 24v solar panels it switches to 24 volts and overcharges the batteries. I continue to have dead batteries in the morning even after going to 6 100ah AGM batteries 8 months ago.

QUESTIONS:
1. Is there a MPPT charge controller that will stay on 12v and dump solar voltage at 14.8v? I'd love to see the battery voltage stay closer to 13v when the system is dumping.

2. Do I need blocking diodes at every panel separating them all (12v and 24v)? Is it possible the solar panels are draining the batteries?

SORRY for the long post, I was trying to paint a clear picture. ANY help is greatly appreciated!!
Thanks,
John

 

[Supervstech]

Wait…
You have different voltage panels connected to the same controller? That won’t work.

The controller needs the series to be of the same multiplier.
It would be better to have a controller for the 12V panels, and a another controller for the 24v panels.
The battery voltage when scc is set up should determine the charge parameters… get better scc…

1000Ah! That is some serious heavy batteries! What kind are they?

 

[GLC]

I looked for a similar thread and didn't find an answer. Here is my situation. About 15 years ago I bought an acre of undeveloped land and built a "cabin". The power company wants $63,000 to bring power in. Back then I used it for snowmobiling and hunting so I brought a old used solar system up. 12v Trace inverter (220v), approximately 700w of mixed solar panels, a 1000watt wind generator, an unbranded charge controller, and 6 rv batteries (12v). The charge controller is wired to a 12v 100 amp water heater "dump". The system 0was adequate at the time, but I seldom had power in the mornings (battery voltage being below 9.5v).

I began going through batteries, they lasted around 12 months. I installed a diode at the wind generator but it didn't help the battery voltage. My charge controller isn't wired like most, the solar/wind generator goes directly to the batteries and the controller dumps at 15 volts down to 12.6. I can't adjust the end dump voltage, its fixed at 12.6. I've never liked that, it seems to deep cycle the batteries.

In the meantime I've divorced and retired to the cabin (2.5 years ago). Recently I purchased 4 24v solar panels and replaced 4 12v panels that were only putting out around 10v. This was a game changer for power during the day, doing laundry is not an issue (no generator required). I had read that a MPPT charge controller would accommodate the 24v panels.

I bought a 100amp MPPT charge controller off of ebay but it will not stay on 12v with the 24v solar panels it switches to 24 volts and overcharges the batteries. I continue to have dead batteries in the morning even after going to 6 1000ah AGM batteries 8 months ago.

QUESTIONS:
1. Is there a MPPT charge controller that will stay on 12v and dump solar voltage at 14.8v? I'd love to see the battery voltage stay closer to 13v when the system is dumping.

2. Do I need blocking diodes at every panel separating them all (12v and 24v)? Is it possible the solar panels are draining the batteries?

SORRY for the long post, I was trying to paint a clear picture. ANY help is greatly appreciated!!
Thanks,
John

First, questions, when you say 6-1000 AH batteries, did you mean 6 - 100 AH batteries?
Second, are you only using your 24 volt panels or using the 12 and 24 volt together? If together, are they wired in series or parallel or do you know what that means?
Third, have you thought about hooking up separate solar panels to a DC water heater element and bypass your batteries saying them for your other electrical needs? You could also use a dual dc element like I have and run one side directly off solar panels and the other side to be used as a dump for your wind generator?

DERNORD 36V 1200W Stainless Steel Heating Element Immersion Heater Submersible Water Heater Element with 1 Inch NPSM Fitting Double U Type - - Amazon.com

DERNORD 36V 1200W Stainless Steel Heating Element Immersion Heater Submersible Water Heater Element with 1 Inch NPSM Fitting Double U Type - - Amazon.com

www.amazon.com

Fourth, Using a MPPT controller like mine, you will be able to use it for 12 volts or in the future use it for 24 volts when you upgrade your system. It is a beast and will read your voltage and set automatically when when you hook up your batteries. Just bear in mind that, always hook up batteries first and the panels second so it will read the voltage in the batteries first and the panels second.
https://www.amazon.com/gp/product/B07429RK43/ref=ppx_yo_dt_b_asin_title_o05_s00?ie=UTF8&th=1

 

[fixit1]

Hello, oops 100ah AGM batteries, and yes I'm savy with electricity and definitely understand series and parallel circuits. The 12v water heater is in my 300 gallon fresh water storage tank. Its only purpose is as a dump. It actually works too good, the relay gets to cycling often and wears out. Yes, I have 12v and 24v panels hooked up in parallel. They are not all close to each other otherwise I could wire the 12v in series if that would help my cause? Should I disconnect the 12v panels? Surely they are helping when the batteries are at 9v? The wind generator takes a 15 mile an hour wind to get it past 13v, but its definitely helping at lesser wind speeds (say 11v) when the batteries are dead.

I'm retired on a fixed income and typically dont have much at the end if the month, I do have a little in savings for emergencies. So unfortunately I can't spare any expense and build the dream system of a wealthy man. I'm 60 miles from town at 6200' elevation, we see -30f during the winter, the lake freezes with 1' of ice on it. The wind BLOWS and snow drifts 3'-6' deep at times. AND I've got a woman in my ear about everything, especially power and water, HOT water! Ha

More to consider: My brother in law scored me a Tesla Powerwall 2 that he had left over from a project for a great price. I dont plan to hook it up until EVERYTHING else in the system is correct and unfortunately I dont have the money for the rest of the Tesla set up. And to be honest I'm not even sure what that is! Tesla it tight lipped with their instructions and support, wanting a certified installer to do all of the work! And it seams like they are more geared to a grid tie.

I have $500 that I could put towards getting the Tesla Powerwall hooked up if that would do it?

Again, any and all help is greatly appreciated!
John

 

[GLC]

Ok, here is some info for you. You can hookup different amperage of solar panels together in parallel as long as they are the same voltage. You can also hook up different different voltage panels in series as long as they are the same amperage. You should not hook up different voltage of panels in parallel. They will fight against each other and not play nice. What are the specs on both the 24 and 12 volt panels and how many do you have of each?

 

[fixit1]

Does it matter how the batteries are hooked up? I have them in parallel with the wires on the one battery. It almost seems like that one battery does more work than those further down the line, BUT they are tied together with heavy 6 gauge wire. The last walmart rv batteries worked great for about a month and then began to noticably fade. When I isolated and tested them they were 1/2 bad and 1/2 weak. I replaced them with the AGM and had similar results (amazing for a month or two and slowly had less and less power every morning). I originally though it was overcharging and damaging them. BUT last month I needed a battery and charged one of the old "bad" walmart rv batteries and it tested good! So now I'm wondering what the heck is actually going on!??

 

[GLC]

Ok, I know this may make no sense to you but I did have a similar problem. I had a config of 3p/2s meaning a 24 volt setup. My charging wires from the solar controller were connected to the outside batteries. I too was having a problem of those two batteries were draining faster than the other 4 batteries. I posted on here and was told that sometimes that was normal with multiple batteries and I was given some technical info on why it was happening. To me it made no sense at all since all batteries were tied together with heavy cable #2 but I tried what I was told and moved my solar connect wires to the middle batteries where I had batteries on either side of the connect batteries. Lo and behold it worked, batteries seemed to charge more equally when I moved the cables but 2 batteries, where my inverter was connected to directly, were still draining faster than the other 4. Using what I had learned previously, I then hooked up dual cables to the inverter, positive and negative, to the 4 outside batteries instead to just to 2 middle of the batteries. For some reason everything started working better that it had ever done before. Charging was more consistent and equal to batteries and usage/drain of the batteries seemed to be almost exactly equal. I know it sounds like it does not make any sense but it did work. I am starting to think that it may be better to have charging and inverter wires connected to each battery which sounds totally weird.

 

[fixit1]

Hey I'll try anything at this point! Thanks

 

[GLC]

This was the answer in my question. If needed, I can take a pic of what I did but mine is wired as 24 volts not 12 volts.

Battery wiring question

Can some one post correct pic of the correct wiring for 6 -12 volt batteries wired for 24 volts. I thought mine was correct but woke up this morning to 2 batteries dead killing the inverter. The other 4 batteries are still at 13 + volts. The bms shut off the two dead batteries at a little over...

diysolarforum.com

 

[Supervstech]

Does it matter how the batteries are hooked up? I have them in parallel with the wires on the one battery. It almost seems like that one battery does more work than those further down the line, BUT they are tied together with heavy 6 gauge wire. The last walmart rv batteries worked great for about a month and then began to noticably fade. When I isolated and tested them they were 1/2 bad and 1/2 weak. I replaced them with the AGM and had similar results (amazing for a month or two and slowly had less and less power every morning). I originally though it was overcharging and damaging them. BUT last month I needed a battery and charged one of the old "bad" walmart rv batteries and it tested good! So now I'm wondering what the heck is actually going on!??

Yes, you want all batteries to be connected to each other with IDENTICAL length and size wires.
You want the cables feeding the inverter to be EXACTLY the same length, and you want the positive on he first battery in parallel, and the negative to the last battery in parallel.
It will make a huge difference.

 

[fixit1]

Ok, I'll hook them up as method 2 shows.

 

[fixit1]

I recently moved the solar panels and this is what I have: seven 16.9v 51watt panels and three 250 watt 36.5v panels

 

[GLC]

I recently moved the solar panels and this is what I have: seven 16.9v 51watt panels and three 250 watt 36.5v panels

Guessing 7 panels, 51 watt-16.9 volts-3 amps and 3 panels, 250 watt-36.5 volts-6.84 amps?

If you wire 3P/2S on your 51 watt panels, you will be feeding appx 9 amps at 33.8 volts. 304.20 watts
Then you wire 3/P your 250 watt panels , you will be feeding appx 20.52 amps at 36.5 volts. 748.98 watts
Then with a combiner plug or box, wire the two strings together in series making appx 67.60 volts - 9 to 20.52 amps or 608.40 watts to 1052.20 watts. Kind of guessing when you are mixing panels.
(Actual amperage may be a little higher, I don't know exactly how much the lower panels will pull the larger panels down.)
You will use the lower values because the lower value series strings will pull down the larger value series strings.

So if you want to keep your setup within the 12 volt efficiency zone then this would be your paneling:

You wire 3/P your 250 watt panels , you will be feeding appx 20.52 amps at 36.5 volts=750 watts and call it quits.
Now you are over paneled by only 230 watts which will be fine because normally you will only be producing appx 450 to 600 watts averaged.

Personally I would get another inverter and go the 24 volt setup and have a more efficient setup. You can always do a step down transformer for any 12 volt appliances. With the controller listed above, you can go with either 12 or 24 volts. It works on either one.

 

[GLC]

Also you really need to provide some specs on the no name solar controller and the 100 amp (220 feed) 12 volt inverter that you already have.
Single phase 220 volt 100 amp inverter? What is the wattage on that beast? I just bought a 220 volt, 6000 watt inverter at 6000 watts continuous. That would be about 50 amps. Guessing at 100 amps, 220 volt, yours would be appx 12,000 watt?

 

[Bvillebob]

Might want to recheck your math, 3P/2S of 16.9v/3amps is 33.8v / 9 amps, not 18 amps, I believe.

 

[dstepy]

Also you really need to provide some specs on the no name solar controller and the 100 amp (220 feed) 12 volt inverter that you already have.
Single phase 220 volt 100 amp inverter? What is the wattage on that beast? I just bought a 220 volt, 6000 watt inverter at 6000 watts continuous. That would be about 50 amps. Guessing at 100 amps, 220 volt, yours would be appx 12,000 watt?

The inverter has losses so 6000w/48v/0,85=147A to pull

 

[MichaelK]

I second the question about what controller you are using? You should be expecting years of service from your batteries. If they are dead in a year, you have problems to diagnose. The fact that the controller is feeding the batteries 24V is a bad sign. This could mean several things. First, was the solar connected to the controller BEFORE THE BATTERY. If yes, the controller got "confused" and thinks that it's actually a 24V system, not a 12V system.

To correct this, I would first disconnect both the solar input and the battery connections, so the controller goes stone-cold, then reconnect the battery connections ONLY, and let the unit boot up. Once on-line, then reconnect the solar input.

The second issue is that maybe this is a fake MPPT unit. We really need pics of what you are working with. A fake PWM unit pretending to be MPPT might explain why the batteries are being fed too high voltage.

As others have said, all the panel strings need to be at about the same voltage (±5%) to work together. That's assuming you have a real MPPT. With a fake unit, you are just guessing.

 

[12VoltInstalls]

last month I needed a battery and charged one of the old "bad" walmart rv batteries and it tested good! So now I'm wondering what the heck is actually going on!?

recently moved the solar panels and this is what I have: seven 16.9v 51watt panels and three 250 watt 36.5v panels

I use those walmartha batteries. Going around three years. You can hurt them if not paralleled in a balanced way. Not top shelf batteries but treated well can have a decent or low lifespan cost.
It is important how you cable them.

If your voltage is going below 12.1 or has gone below a few or many times that damages the battery for capacity band lifespan. 12.3 or 12.4 daily low is better but occasionally 12.1 is ok - nevertheless, 12.1 is 100% discharged of usable battery.

As far as “what’s going on” with your recovered walmartha battery- sometimes a good equalize / boost charging will kickstart a lead acid back into useful range. Not a guarantee but you can recover sulfates batteries. Sometimes.

Where are you at on this?

 

[rmaddy]

I would first disconnect both the solar input and the battery connections, so the controller goes stone-cold, then reconnect the battery connections ONLY, and let the unit boot up.

Some charge controllers will still retain the previous voltage setting at this point. Some may require manually changing the voltage setting at this point, before reconnecting the PV. This should be covered in the user manual for the controller.