Anyone working toward Off Grid

[MEMPHIS91]

I have a general question, let us assume someone is looking more toward the worse case scenario idea. And getting new batteries every decade or 2 is not possible. Which type battery would last the longest? I know the nickle iron batteries are great but their charge rate sucks. Would lithium be the next closest thing?

[jeff5may]

Originally Posted by MEMPHIS91

I have a general question, let us assume someone is looking more toward the worse case scenario idea. And getting new batteries every decade or 2 is not possible. Which type battery would last the longest? I know the nickle iron batteries are great but their charge rate sucks. Would lithium be the next closest thing?

Like Steve and Randy have stated, there is no such thing as a perfect storage battery. For one, they burn generated power on the way in and out, to the tune of 10 - 20 percent round-trip loss. For two, their charge rate and capacity are limited: there is a finite number of charge and discharge cycles a battery can provide before it is spent. For three, batteries have a finite shelf life: if they are not used, they will slowly discharge and lose capacity naturally with age.

Whether or not you accept the fact, any available storage battery available today will need to be replaced (regardless of usage) over the course of a decade or two. How much loss of original capacity you are willing to accept is the main factor that will determine your replacement time frame. Over time, the replacement cost is pretty constant: if you install a larger bank to account for the loss of capacity, your replacement will be less frequent, but you will have more batteries in your bank.

Like the others have said, the power utility is essentially a low-loss, infinite source and sink of generated power for a single family home (when it operates). With most modern inverter-driven systems, insertion losses are close to an order of magnitude less when feeding power into the grid compared to the losses of charging a local battery bank. The economics of grid-tying vary with the individual power company and their pricing structure, and are worsening as the general public gains the ability to generate their own solar power. Those of us who did grid ties maybe five or ten years ago got better deals than someone wishing to tie in today. Even so, the savings of needing to maintain a much smaller (backup-sized) battery bank are substantial. You will eventually have to decide whether to pony up big bucks to support your ideal to be grid independent (and the bank it requires), orto save the investment and use the grid for storage.

[oil pan 4]

Originally Posted by MEMPHIS91

I have a general question, let us assume someone is looking more toward the worse case scenario idea. And getting new batteries every decade or 2 is not possible. Which type battery would last the longest? I know the nickle iron batteries are great but their charge rate sucks. Would lithium be the next closest thing?

The cheapest battery that will last the longest and has a good shelf life are lead acid AGM.
Good shelf life high mobility but at high cost are LiFePO4.
Batteries that kind of last forever are nickel iron. But they are expensive, big and have almost no mobility.

[MEMPHIS91]

Yep I could not agree more with everything ya'll have said. I'm not trying to disagree, just trying to really answer Randens question by saying YES I am thinking of going off grid, even though it means BIG changes. And large expense. And large head ache. And probably a mental breakdown every time someone turns on a light, or watch a dvd for longer than 10 minutes at a time.
My question still remains, what would be the best (not perfect) but best with todays market, battery system to achieve that goal. Assume I was handed a $100,000 check (me installing myself of course) and could ONLY spend it on solar.