Need help designing system. I have 6 batteries!

[bbanjoboy]

Howdy.. thanks for adding me to your group.. I am brand new to solar and am trying to figure this out.. here's my situation. I'm building a coffee trailer for my wife and have decided to go solar with it. Our power requirements are minimal. The biggest draw is an 1800 watt deep fryer.. We'll have a couple coffee pots at about 700-1000 watts each and a window unit ac at about 700 watts.. Believe it or not, we CAN eliminate the coffee pots if need be. I got a great deal on a set of six brand new LPF12110 12v 110Ah rechargeable sealed batteries. So .. here's the question.. Should I do 2 seperate systems or one large one. I only have room on the roof for one, POSSIBLY two panels... If I can put 2 on the roof, I could do 2 seperate charge controllers and inverters and 3 batteries per system.. or would it be more efficient to link all 6 batteries in series and put the two seperate inverters on the same battery bank? Also, what would be the best single panel to get if I can only get one as far as wattage goes? We are only planning on being open perhaps 5-6 hours per day.. so hopefully we should have enough time to charge all the batteries during down time... Thanks SO MUCH!

 

[BentleyJ]

Your available energy is going to be severely limited by only having 2 panels. I've seen mobile solar where the panels slide or fold for travel then can be deployed but it gets complicated.
Before you go any further, please define how many hours a day said appliances need to operate. This will determine how many kWh are required and if the project is even close to being possible.
Lesson 1: Don't start purchasing equipment until the electrical design is complete. Those 12V batteries are going to become an issue because they will need to be connected in series for a 24V or 48V inverter. Some batteries are capable of this some are not. Its better to have the battery voltage match the inverter voltage so the cells stay balanced under the control of the BMS.

 

[ksmithaz1]

A "solar" day is generally 5-6 hours. All the appliances should not run at the same time, but they could. 700watt window AC huh? 2 panels isn't going to do much, Two 500W panels may net you 800W/hour sometimes. You need to get a real audit of a typical days use of energy, along with a peak demand number. I don't think 3KW will cut it, maybe 6 and you are going to need a backup 6KW generator.

 

[richard cabesa]

Lesson 1: Don't start purchasing equipment until the electrical design is complete.

This. It is all just pretty much basic math. Do an energy audit of the equipment you want to run And the length of time it needs to run. Then this will give you how much energy storage you need. Then this will tell you how much energy generation (solar or genset) you need to replace what you have used so you can operate the next day

 

[Hedges]

Our power requirements are minimal.

You bring new meaning to the word "minimal".

I would suggest going the DC Solar route. Put up PV panels for the marketing angle, charge battery at home, and fire up the smoke belching generator when necessary to keep serving.

Quieter and nicer, use PV & battery for little stuff like water pump. Burn propane for cooking and boiling water. Maybe you can have custom dual-fuel units built, e.g. have fitting or electric heating element installed. Start the day out pre-heated from home (with extension cord), and PV might keep it at desired temperature, process limited drinks and food. But use propane for volume production.

How about an awning for customers to stand under? Mount hanging PV panels that lift up on struts.

 

[sunshine_eggo]

Howdy.. thanks for adding me to your group.. I am brand new to solar

As evidenced by your perception of "minimal" power.

and am trying to figure this out.. here's my situation. I'm building a coffee trailer for my wife and have decided to go solar with it. Our power requirements are minimal.

The biggest draw is an 1800 watt deep fryer..

Substantial power consumer.

We'll have a couple coffee pots at about 700-1000 watts each

Again, substantial power consumers.

and a window unit ac at about 700 watts..

Major power consumer

Believe it or not, we CAN eliminate the coffee pots if need be. I got a great deal on a set of six brand new LPF12110 12v 110Ah rechargeable sealed batteries.

So .. here's the question..Should I do 2 seperate systems or one large one.

Neither. Link #1 in my signature. Calculate available solar and conduct an energy audit. Don't by anything else.

I only have room on the roof for one, POSSIBLY two panels... If I can put 2 on the roof, I could do 2 seperate charge controllers and inverters and 3 batteries per system.. or would it be more efficient to link all 6 batteries in series and put the two seperate inverters on the same battery bank? Also, what would be the best single panel to get if I can only get one as far as wattage goes? We are only planning on being open perhaps 5-6 hours per day.. so hopefully we should have enough time to charge all the batteries during down time... Thanks SO MUCH!

solar panels come in all shapes and sizes, but let's assume they're 400W EA, and you get GREAT sun. That's about 4kWh/day assuming you're getting unshaded panels from sunrise to sunset.

That will allow you to run the fryer for 2.5 hours. That's it. If you use more than that, you'll perpetually eat into battery capacity. Your batteries have 7.9kWh of storage - half of which is usable if you want to get a few years out of them. So, now you're down to 4kWh/day of storage - again about 2.5hr of fryer running.

Assuming you're open from 9-3, you can run only the fryer for most of that time, and you'll need to recharge 50% of your battery capacity every night.

 

[richard cabesa]

I guess’s no one including myself who replied to thi thread really addressed your real question about one battery or two? ONE!,, always build the biggest battery you can to account for a possible high load.

my six 100 AhH LiFeP04 are in 3P2P configuration. Each 3P have their own disconnect switch and then-combine through a class T fuse to buss bars where everything else splits.

I can run multiple 12v loads or inverters from this point

 

[bbanjoboy]

Thanks so much.. While most of the answers were a bit snarky, I TRULY do appreciate them. I didn't think one fryer and one AC unit with a couple lights was going to be THAT big of a deal.. These batteries I purchased was the first thing I ever explored in the solar world.. They are brand new and listed for $600 each.. I had to move quick on them and got them all for $500 without having time to research.. You win some you lose some.. I don't believe at this point.. thanks to all of your input.. that moving further in this direction is a worthwhile endeavor. The 'cheapest' inverters I've found are 5000 watt ones at harbor freight for $400 each.. My initial thought was I could purchase two of them and 2 400 watt panels along with a 50 amp charge controller and I'd be into this for around $2000 and have a set up that would be able to be open for 5 hours per day.. I suppose that ain't gonna happen.. So, I'll get a small panel box and go to setting up power from a generator.. Thanks for the quick input.. If anyone wants to purchase these 6 batteries for what I gave for them, let me know.. I'm in North Central Arkansas!

 

[Partimewages]

Just remember the first thing with solar is planning. Unless you have unlimited funds this will be the least expensive route. Just FYI your not going to want HF cheap inverters in the future! Just more money wasted.
There's a for sale area on the forum to post your batteries.

 

[Hedges]

?

Because your loads are resistive heating elements (except for A/C), they are easy enough to power with cheap inverter, only need continuous rating sufficient for watts on appliance nameplate.

Any motors will require an inverter 5x as large, for starting surge. The small A/C might be rated 500W, would need 2500W for a second to start. (I've measured mine.)

Of course, fryer and coffee pot don't run 100% of the time. You could note percentage of time it is switched on, or get a Kill-a-watt meter which will record it.

Inverter and appliances have "Watt" ratings, inverter needs to supply those peaks (plus motor starting surge.)
Over time, appliances consume watt-hours. Battery needs to supply that.

Most food carts use a generator, or propane for heat.

Be sure to use GFCI for electric. You can buy a portable GFCI cord if not built in to your generator or inverter.
I think propane heat is the way to go, rather than a generator to set out, and do maintenance on. Can you get a coffee pot of suitable size for stove top?


These batteries?

http://www.efirstpower.com/PDF/LFP12110.pdf

Six brand new for $500, if shipping to California was reasonable I'd be interested. I use AGM for grid-backup system. Cycled daily, only good for a couple years, but for backup use could last a decade. Maybe you'd want to have backup at home.

 

[AlpineJoe]

http://www.efirstpower.com/PDF/LFP12110.pdf

Wow, yeah, from that datasheet they are lead acid AGMs. Using LFP as the pn is not cool.

For the OP, lead acid battery capacity drops under heavy loads. If you look at the datasheet (if these are actually AGMs), these batteries are in the 68 AH capacity at 1C discharge, and that's down to 9.6V. You inverter might not let you get that low before cutting out.

 

[wme]

Have you ever noticed how few food trucks and coffee trailers are solar powered, an that most have generators or a LONG power cord??
Heating anything with solar is the most inefficient way possible to do it.
Running some lights, a small fridge, some fans that's what solar does best.

 

[Tomthumb62]

didn't think one fryer and one AC unit with a couple lights was going to be THAT big of a deal..

Since your new to solar and probably have zero idea how much electricity you consume on a daily basis (most people have no clue) then it’s understandable that your perception of your energy needs is off.

I mean you can’t see the energy flow through a hairdryer anymore than you can see it flow through a heated blanket. One uses 1800W and the other only 150W. And grid powered electricity is so cheap that 2000W feels about as cheap as 200W.

The snark is just from the really smart people that get tired of all the new people who haven’t yet learned that their idea of “minimal energy needs” is way off base. Think of it as a type of hazing initiation into the solar club. I got spared that hazing because instead of asking questions right away I read a LOT of posts on this forum and learned how to do an energy audit and learned that solar power, especially the battery powered kind, is EXPENSIVE.

Now to your credit, you did get a good deal on those batteries. As for an inverter, if you can ditch the air conditioner and limit how many devices run at once, you can save money. And don’t waste your money on harbor freight junk, you’ll shoot your eye out kid. @Rednecktek can tell you exactly why not.

Edit: just saw that those batteries aren’t lifepo4 but AGM. Not such a good deal anymore. Any way you can return them? Lead acid is a pita.

 

[bbanjoboy]

Update: I have found that I can replace my fryer with a propane one as well as a propane instant water heater.. SO.. this means that all I am looking at for electric is a 400 w AC window unit, an LED light, the vent hood, and a small hand blender. Nothing else. Obviously I can get by with a small generator, but am having second thoughts about going solar again... Any thoughts are appreciated.. No sense waisting these batteries if I can make them work right?

 

[Hedges]

7200 Wh batteries x 50% = 3600 Wh usable, divide by 400W = 9 hours continuous. Less various inefficiencies, maybe 7 hours.
What percentage of the time is it on vs. off? Coffee trailer would have large opening to the outside. You have heating appliances inside. Probably continuous? But who's buying coffee in hot weather.

How about just vent fans?
Maybe the A/C can be blowing cool air on the staff, and heat from appliances is exhausted by a vent.

400W running x 5 = 2000W surge, need an inverter at least that big. A 12V inverter could do it.

Maybe this can work now, depending on your needs.