Need help completing 24v off grid ranch system

[SloanStar]

After talking myself out of a 12v system, I decided to go with a 24v system.

I went ahead and purchased an EPEVER Triron 30a mppt charger controller and two 36v 310 watt panels.

My biggest dilemma is knowing how many batteries this system can effectively charge and what size inverter would work well in this setup.

I plan to use this system at my ranch in Trinidad Colorado, its bare land, no utilities and no cabin yet.

I did want to setup it up now, so that meanwhile I can go camping and possibly use it for lights, charging power tools, music etc...

Ultimately, once built, I want to power the tiny cabin, lights, water pump, ceiling fan, maybe a mini split AC unit, Microwave, single induction cook top?

I have access to a particular battery, and I dont think they are ideal for solar, but its what I have to use for now: 12V Enersys Genesis XE16

Any advice on completing this build would be much appreciated, and I will post the fabricated ground panel stand and weather proof install at the ranch

Insulating batteries in another concern, thinking maybe an insulated plywood box???

 

[Steve_S]

With a 24V based system, you can safely go up to a 4000 Watt Inverter without much ado. Beyond 4kw, things get a touch more complex and if you need bigger than that, 48V is the next step. Before buying any more STOP ! Have a plan and path as to what you are doing and where you want to take the system (size & capability). You do not want to buy gear now only to have to replace it later, unless you want to chuck money away.

I you want to grow a system, then all the bits should be scalable. Meaning using stackable / linkable MPPT Solar Controllers, inverters which can be stacked as well. You do not want to mix'n match too much either because that inevitably leads to problems and quirkiness. Of course budget is a limiter - director as to what and how you can do things.

Batteries.... Ideally, LifePO is the way to go, cost, safety, reliability are there. They charge faster than Lead (and variants) and won't blow up & burn your house down. They do cost a bit more up front but you'll get a lot more life & use than any other. Case in point. My FLA bank at todays price is $3,200 plus tax (Canadian dollars) my new 24V/400AH LifePO pack cost me $4,000 CAD plus duty ? (it is in transit, arriving tomorrow). I could have DIY'd it for roughly the same if using new, or went used and DIY'd that for my place for much less.

Look at my sig, link there to my current setup with some detail there that may help you ponder a few things.
Hope I Helps.
Steve

 

[SloanStar]

Steve, thank you for the reply! So 4000 watt inverter gives about 33A AC unless my math is off. That’s incredible! That solves problem 1!

I have flexibility on the inverter but not the batteries. That specific brand of lead acid AGMs, is what will keep this project ultra cheap! Mainly cause they’re free. I divided your 400ah bank to these 16ah lead acids, and I need 25 batteries! That’s a huge bank! I plan only on using this system on weekends at most 2 a month maybe best cause scenario 3 times a month Friday and Saturday so 6 days a month max.

I do like that I can have serious power if I need it ( build stuff with power tools etc) Its definitely not going to be for extended periods of time....It’s a weekend getaway kinda place. Ultimately going to air b&b it most the year.

 

[gnubie]

Your two panels will produce 620 watts at a maximum. Depending on the angles they may not even reach that but for the sake of it, let's assume they do. If they get the normal curve of sun exposure over a day and are pointed in the best direction for your hemisphere you might find you get 4 hours at near 620 watts and 4 hours at half that, averaged into 2 time bands. This is only a guesstimate, your actual figures may be far better, or far worse. That's about 3.7kWh / sunny day. With all the stuff you are looking at powering that just isn't going to be enough to cover that consumption and bring a modest battery bank up to full charge daily, and that is something you do need to do with lead acid.

 

[Steve_S]

I built my place with DeWalt 20V cordless for the most part, Table Saw, Compressor, Mitre Saw only got Genny Power. I just wouldn't stress my solar gear with that kind of nasty loading. I live in my place year round, so that's a bit of a different picture and being offgrid, remote in the bush, I 'need' to depend on my gear being in good shape at all times. My Midnite Classic charges up my FLA's pretty quick considering. This morning, the bank was at 70% by 1pm I was at 92% on a slightly overcast day.

Will has a couple of good tut's on the website, you should look at those and ask questions, the ONLY stupid question is the one that remains un-asked.

 

[SloanStar]

Thanks gnubie,

So let me try to understand this a little more...Big IF...my panels produce 3.7kwh on sunny days that would that translate to a 154.17 ah battery bank at 24VDC that it should be able to charge?

So I would need 20 x 12v 16ah batteries wire in series/parallel which would give me 24V 160ah bank.

Starting off with no cabin...3-4 LED light bulbs, 5 minutes on the 12v water pump to wash hands and maybe shower, charge 2 Milwaukee 18v batteries, charge cell phones and flash lights, and listen to music.

With a cabin I imagine 6-8 LED 9w light bulbs for 5 hours at night, 10 minutes on the 1600w induction cooktop to cook a meal, Run 900w mini split 1-2 hours during the hottest time of the day and or cieling fan. 10-20 minutes for the 90w 12v water pump, charge phones, and maybe run the 700w microwave for 5 minutes.

If I cant run the above how many more panels and batteries do I need, I have a guy selling those 310w panels for $80
And batteries are free

 

[Steve_S]

@SloanStar a thought to ponder on maybe. I built my pumphouse first then doubled it's size to also incorporate a powerhouse. 14'x6' total size. The advantage it provided a secure spot for some things, access to power & water was handy. For higher security things I also have a 20' Sea Container which also has the solar rack hanging off one side.

IF you can get 310W panels for $80 a pop, dude BUY AS MANY AS YOU CAN ! I am running with 8x 260P panels for 2kw, would love to double that for so cheap ! Sell the extras if you have any left over after your planned out.

 

[SloanStar]

@Steve_S He buys them from solar farms after weather related insurance claims. Apparently they replace the whole string damaged or not. I found him in Dallas TX (pickup only). I just checked his listings and now hes selling 260w panels for the same price now. :/

I didnt know anything about solar when I bought these two 310w panels, and thats all that I could fit in my truck at the time.

I imagined using them at my ranch for messing around and learning. But your right! I should buy a bunch of what he has now. I want to do a grid tie

project at my house eventually.

But as far as using what I have now for the ranch, so that I'm not sitting in the dark all weekend, or having to drag a generator out there. I want to nail down using what I already have.

Im sure I bought this stuff prematurely, but I've got $300 in the panels and charge controller and I have 10 free batteries.

My industry also disposes of 12v 16ah batteries before they have gone bad as a proactive measure. So getting 10 more for free is easy

 

[Picasso]

The computer world uses those small 12v 16ah lead acid batterys in UPS systems. APC makes some nice battery racks and trays for them. if you got a nice supply of them worth it to hunt down some of those scrap APC battery racks.

 

[svetz]

... two 36v 310 watt panels....how many batteries this system can effectively charge and what size inverter would work well in this setup.
,,,I plan to use this system at my ranch in Trinidad Colorado ...

From the insolation map, Trinidad is an amazing spot for solar with a number of 6.6!

Battery Size
So at 80% efficiency, 620 W x 6.6 x .8 = 3.2 kW per day! So, at 24v, that's roughly 136 AH (or at 12V 272 AH).

Inverter Size
It depends on how you use power. If you're going to drain that 3.2 kW each day at a steady rate (e.g., power lights that are always on) that would be 3200/24 hours = 140W inverter.

But no one does that, most people use a lot of power in chunks (e.g., when a refrigerator compressor kicks on). The only way to know that is to measure it and you'll need an inverter that can handle your biggest usage.

Most people do this the exact opposite way, that is they tally up a power budget, then figure out what inverter/solar/battery they need to accomplish it.