Solar without batteries

Ok the big question. Lets say I have a 2500 watt inverter that makes 120 volts AC from 24 volts DC. How many watts in 24 volt solar panels would I need to run direct into the inverter without batteries? This is to address the possibility that my batteries died and I could not replace them. Would a 2500 watt array be enough to feed a 2500 watt inverter during good sunshine? Can it even be done? KF

 

you can make a simple large capacity capacitor from aluminum foil and saran wrap

 

You should be able to buy a capaciter or two that , in the event of battery failure and no way to replace them could be used in place.....

 

So, what you saying is just leave the batteries in even if they are worn out? KF

 

yes you can buy better capacitors...
now
but when TSHTF knowing how to make your own is a good thing
they do burn out

 

Showed up in a lot of computer motherboards and not the cheapies.

There are a few versions of the "how." Which is SOP with espionage.

 

Outback says their inverters won't work w/o batteries in the system ( though they don't say how good they have to be ).

But from a purely practical standpoint, you wouldn't want to operate your system without them ( or a grid tie ) anyway because here is what would happen:

To start with, you'll need 3 to 3.5kw to even hit 2500w output, based on what I see out of mine. By the time you factor in charge controller loss, and battery loss ( which I suspect would be greater if you had crappy batteries ), inverter loss, AND (the biggie) the fact your 245w panel (for example) is only going to ever give you 245w on the most rare of days ( great sun, perfect angle alignment, perfect temp ), you need to factor in AT LEAST 1/3 more in panel than you want in output.

2nd:

You only get electrical flow when you have something on the 120v side of the inverter requiring electrical use....say a fridge, or whatever.....otherwise your output is zero.....you just have backed up potential.

OK, say you're actually managing to use 2500w in the form of 120v power....around noon on a good solar day....what happens if a cloud goes over ? Or you can't match load to inverter output ? ( You realize how tricky that would be ? )....THAT is the real reason for batteries.....a reserve pool of power to handle that management, and the fluctuations of your panel input ( which are a LOT, believe me.....early morning, late afternoon, you won't do anywhere close to your array KW ).

SO, in conclusion.....yes, batteries really are a major part of the system. That is one reason I was so tickled to find the Absolyte GNP batteries I have in my system ( especially for the price I got them...ahahaha ).....20 year life batteries ( depending on the number of cycles of course ) in light use situations ( and maybe more ). Before you invest in batteries, you might also want to consider the Edison iron based battery.....only source right now seems to be imports from China, and they ain't cheap, but for a 50-100yr life battery, it might just be worth having at least a few on hand IF one anticipates the end of the world.

 

A 20 year Battery would last as long as my propane. Ill be researching these. Thank you. Again ,this forum just rocks. KF

 

Andy, Is this the Right website?

UPS Batteries from Power Systems Specialists

I see many models which model do you have and what volt size? KF

 

I have the 100G25 "blocks" ( 6v, 1200amphr )....which are really just 3 individual 2v cells in a case of 3 cells.

Then there are 4 sets of these connected to make a 24v, 1200amp/hr battery pack.

Unlike the typical battery, each cell has two sets of connection (pos/neg), but is an individual cell ( can be slid out of the metal case if you can handle 200lbs or so of weight )

Here's one of 3 sets of these I hauled home I bought out in Kansas from a buddy that works at a cell phone company. His company was being bought out, and he was told to "get rid of everything in the warehouse for scrap"....which included 2 brand new sets of these, and one that was about 4 years old, which is when they pull them from service routinely, regardless of condition. ( and it checked almost at new specs )



Scrap price ? 300 bucks.

New price ? ( be seated, and have no beverages in your hand)

About.......... 15,000-20,000 depending on where you shop.

When he told me what he had, I said I'll be there tomorrow, and virtually walked out the door and got in the truck and drove 1500 miles.

 

Those are really nice Andy. You will need some power to fully charge them up. Maybe you should just giv'em to me. LOL super score

 

Ok, it says that unit is 609 pounds. Im not able to deal with that. Im looking at the Deka models now. tHE 6 volt GEL Monobloc What do you think? KF

http://www.dekabatteries.com/assets/base/1460.pdf

 

I wish you well with your solar project and will follow with interest.........Ross

 

Don't know anything about them. I used the Deka Flooded cell 6v initially, and that's what I put on my buddy's system few months back. That's the tall one with the rope handles in the PDF you listed. They weigh about 110lbs each, so you can handle them yourself or one stout boy, and run about 400amp/hr for a 6v version.

Good battery (for the money), locally available here ( Deka dealer in town ), so shipping isn't an issue. About 250 bucks/ea. Expected life with light use is probably 7-10 years.


As I said, if LONG term life is what you're after, you really ought to look at nickel-iron batteries ( Edison battery )

nickel iron battery information

US Supplier:

Nickel Iron Batteries - A Lifetime Battery For Your Off-Grid System (or On-Grid Backup)!

 

Yeah...it would pay to get to know somebody in the telecom field. My understanding is they have a cycle they replace them on, regardless of condition.....keeping service online being more important that price of batteries to them. Start nosing around and find who runs your local cell services.

And, of course, if the SHTF big time, one of your first salvage operations might want to be that little shack at the base of a cell tower......

 

Here is what I have so far from the Deka gel monobloc 6 volt 210 amphour. 300 bucks each. I would need 4 to have 24 volts. thats 840 amp hours per gang of 4 correct? KF

 

Nope. That's 210amp/hrs at 24v.

When you wire in series ( to up voltage ) the amperage remains the same.

You get EITHER 24v OR 840 amp/hrs, but not both. Sorry.