little help from the experienced

[Lorrainelamb]

I have lived off grid for 20 year. My first solar system was a 22w panel that ran 1 light and a radio. The second was 100 watt that ran several lights and one fan. Now i have a .5k 12 volt system that runs my whole house. Fans, computers, lights. I put each one up.

Now i want a swamp cooler. it is hot in the CO high desert. I have 8 250v 24w panels and 6 12v lead acid 104ah batteries wired series/parallel for 24 v.. Both of which i got at a huge discount due to being used. The batterys are a year old and have been checked and charged by professionals.

I ran 1/0wire from the panels to the shed, it was 60' underground in conduit. I have the first set of 4 panels up and wired to 24v but i think i am going to have to rewire to 46 v so that the next 4 panels can run on the same wire. I bought a 40a mppt chg controller for the first 4 panels and planned to parrallel it with the second set of 4 but now realize that the wire is too small and i am NOT going to run another line. So will change to 46v panels and 60a?chg controller?.

I have hooked the first 4 up with a combiner box/breaker box. to mppt chg controller just to get the batterys back to full as it has been 2 weeks. This weekend i will set up the fuses, disconnects, indoor plugs for indoor dc 12v lines and start to add the lines for the 2000 watt inverter that i will buy next.

I plan to use a 60a fuse between mppt chg controller on #6 wire 2" long. I need to know if all this is ok the way i have it planned or if i need to change anything before I do it.

[Sunking]

OK you have been on solar for 20 years and still do not know 12 volt systems are toys. You got yourself trapped inside a 12-volt box and paying the price for it. You also do not know you should not use parallel batteries. You are doing that because of being married to 12 volts. Get a divorce, 12 volts is killing you.

Example you know about MPPT Controllers, but does not sound like you know why and how to use them. Example there are many Controllers that will allow you to run Panel Voltages up to 600 volts. A 1000 watl panel System running at say 500 volts only requires a 2-Amp Maximum current. To keep within a 2% voltage drop allows you to use the minimum required 14 AWG wire up to 1000 feet. You used very expensive 1/0 AWG just to get you 60-feet.

Same thing on the output or battery side. 12-volt is extremely limited. If you have a 60-Amp Controller into a 12 volt battery have shot yourself in the foot because you just limited maximum panel wattage to 800 watts. With 24 or 48 volt battery limits input to 1600 and 3200 watts respectively.

MPPT has another huge cash advantage. It allows you to use much less expensive Grid Tied Panels that run at much higher voltages. They cost 1/2 of what 12 volt battery panels cost, and it takes less hardware and labor to install with fewer eggs in the basket to break.

Might wanna tap the breaks and rethink everything you thought you knew.

[Lorrainelamb]

Number one. It was you I was hoping to hear from despite the fact you are so caustic. And apparently can't read either. My batteries are in series parallel for 312a at 24 volts.

[Lorrainelamb]

Also I have no grid to tie to. So it is only off grid. I am happy to learn from you if we are talking about my system not a hypothetical one.

[Sunking]

And apparently can't read either. My batteries are in series parallel for 312a at 24 volts.

Perhaps I cannot read especially when you say:

I have hooked the first 4 up with a combiner box/breaker box. to mppt chg controller just to get the batterys back to full as it has been 2 weeks. This weekend i will set up the fuses, disconnects, indoor plugs for indoor dc 12v lines and start to add the lines for the 2000 watt inverter that i will buy next.

Sure sounded like a 12-volt system to me. Then you said this which is electrical non-sense.

I have 8 250v 24w panels and 6 12v lead acid 104ah batteries wired series/parallel for 24 v.

So how are you going to connect these 24 watt, 250 volt panels?

I think what you are trying to say is you have 8x 250 watt, 24 volt panels for a total wattage of 2000 watts. You have basically exceeded or maxed out a 24 volt system. With 2000 watts of panels operating into a 24 volt battery would require a 80 amp controller with no room for growth. A 60-Amp Controller you plan on cannot handle 2000 watts of panels. It would cut off at 1600 watts robbing you of 400 watts.

You are in 48 volt battery country my friend. You can do 24 volts, just loose two panels. Or smart money obtains two more of the 6-volt batteries, wired all in series for 48 volts, then that 60 amp controller can grow to 3200 watt sin the future is needed. Use that 12 volt 2000 watt inverter as a boat anchor. You will not need al that large expensive cable, and equipment matched to do what you want.

[bcroe]

You might research the latest mini-split heat pumps that can run directly from solar
panels. These units tend to be extremely efficient and have other advantages, but
will require several panels in the 250W class, far more economical than those tiny
ones. The mini-split would only run in the day, but that is when you really need them.
If things got really bad, a rather small generator could also run them through the line
backup power input. These do not have the big input power surge at startup of older
technologies, easing any AC input capability.

With a multi directional array like mine, you would have full power some 8 hours a
day, no bell curve. Bruce Roe

[Lorrainelamb]

I am not sure why I would want a mini split heat pump?

[Mike90250]

I am not sure why I would want a mini split heat pump?

Because it is nearly as effective as the swamp cooler, and it gives you heat in the winter.

[Lorrainelamb]

Sunking I have 24v panels connected in series parrallel for 48v incoming 2000w to a 24v battery system with a 24/ 12v converter for 2 select loads but mainly inverter power. I am just trying to figure out how to connect the first 4 panels to the second 4 panels.

[J.P.M.]

1.) Have you ever lived with a swamp cooler ? I'd suggest if you haven't - be cautious.

2.) Without more information, it looks to me like you have the cart before the horse.

3.) If you haven't done so yet, if it was me, after I first sized an evaporative cooler that'll do what you want in terms of cooling effect, I'd see if one could be found of that size that will work with your existing PV/batteries with respect to starting and running loads before I reconfigured the system.

Or, reconfigure the system then find a swamp cooler or a small A/C unit that meets the cooling duty as you determine.

How much energy are you getting from the current PV/batteries in terms of kWh/yr. on average ?

[Lorrainelamb]

J.P.M. you are confusing my 2 systems.

For many years I have used my 0.5 kilowatt 12 volt system. I dont want to add to it. I have been running a portable swamp cooler with a 150w inverter plugged in to my 12 volt system. It is all I need but I have to be very careful not to run my batteries down. We live in very very dry desert. Swamp coolers are in everyone's house.

Now I have a new system started. It has 4 250w 24v panels in series parrallel for 48v isc18a. It is going to 6 12v 104ah batteries, wired series parrallel for 312ah, 24v. This is for a 24v 2000w inverter to run swamp cooler, washer and occasional food processor.

I have enough panels to add 4 more. I am trying to figure out how to add a separate combiner box and attach to the 1/0 wire that is run underground 60' to my batteries.

[Lorrainelamb]

Or do I just need a larger charge controller and what would you suggest?

[Sunking]

With 8 panels running 24 volt battery you have 4 possible configurations. 2 of the 4 options will not work

1. 8S1P, Will not work unless you have a Controller that can handle 600 volt input. This would be the best option if it were possible.as it would be the most efficient and least expansive..
2, 1S8P, Not even remotely possible and foolish
3. 2S4P, would work, but poor efficiency
4. 4S2P is for you my friend, your only logical and best choice.

If you insist on 24 volts will require a 80 amp Controller, 60-Amp will not work. However even with an 80-Amp Controller, you will not have any room for growth. Best advised to move up to 48 volts now while there is opportunity.

[Lorrainelamb]

Yes Sunking that is what I plan 4s2p. And I thought that would need a 80a chg controller. Thank you.