what batteries would you recommend?

System · March 2011

i am probably the greenest/newest member here, so please be kind

i want to make a start on my long term goal "off the grid"

what kind and type of batteries should i be looking at? gel?

from the research it looks like i will need a few 12v's and they look like they are around $100+

my goal is to power the entire house. But getting my feet wet is my short term goal

live in FL

thanks ahead of time
steve

Cariboocoot · March 2011

Re: what batteries would you recommend?

Welcome to the forum.

Nix on the gel batteries!
For a first set, get the inexpensive "golf cart" type deep cycle FLA's, commonly referred to by their Trojan model T105. You can get "no name" ones from places like Costco or Sam's for little $. They make good first batteries because they offer good Amp hours for the money, and FLA's are forgiving of "mistakes" (over/under charging). And they let you monitor the Specific Gravity so you have a better idea what the State Of Charge really is. That is essential for "dialing in" your system to your needs.

Now, as for your goal of powering your entire house .... Why? Got not utility? Rule one of solar power is that it is expensive. On average, grid-tie solar produces power at a cost of about $0.50 per kW hour and off grid is twice that. Compared to utility power, it's no bargain.

As for how you go about it, here's the basic drill:

1). Conservation, followed by conservation. After that, more conservation. Reduce consumption as much as possible because solar power is expensive. Ever $ spent on conservation is worth two spent on production.
2). Plan for your loads. You need real world numbers for maximum power consumed at any time, total Watt hours per day, and type of loads. This gives you the info needed to pick an inverter and size the battery bank.
3). Once you have the batteries figured out, you can determine how large of an array and charge controller you need to recharge them.
4). Don't forget the back-up power.

Discouraged yet?

System2 · March 2011

Re: what batteries would you recommend?

haha wow......... not discouraged just a tad smarter (i think):D
thanks for time. Yeah i'm looking into solar as an alternative if SHTF. I know energy is going up, so i'm asking and researching the things i need now.

yeah a lot to learn. but i'm excited.
steve

BB. · March 2011

Re: what batteries would you recommend?

Steve,

Just some very rough numbers (they allow you to at least plan your options without spending hours pouring over design variations):

$0.10-$0.20 per kWH Grid power
$0.15-$0.35 per kWH Grid Tied solar (no emergency/backup power)
$0.45 to $0.75 per kWH Grid Tied Solar + Backup Power (hybrid inverter system)
$1-$2+ per kWH Off-Grid Solar Power
$0.50 to $2+ per kWH for backup genset fuel

A typical North American home probably uses 600-1,000+ kWH per month (more if you have A/C).

A good starting point for an Off-Grid Home is around 100 kWH per month for a solar PV off-grid system... Enough power for lights, fridge, clothes washer, laptop computer, radio, perhaps a small well pump.

A 100 kWH per month system will probably cost you ~$10,000 plus you will need to replace the batteries every ~5-10 years, repair your inverter/chargers every 5-10 years and replace them every ~10 years...

A 100 kWH per month off grid would be ~1,000-2,000 watts of solar panels and is usually a doable DIY project (with enough research) for many people.

A 500-1,000 kWH Grid Tied system can be done DIY (there are some nice threads here)--But you will still (usually) need utility approval, building permits and an licensed electrician for your install.

So make sure you have money in the bank to pay for this (in my humble opinion, never take out loans to pay for solar power--it is not a good "investment").

Your power usage will go up over time... My home is on the grid but I did work fairly hard on conservation... I got down to ~175 kWH during one summer month (we have natural gas for cooking/hot water/heating, don't use central heat during summer)... But as our family grew (freezer + extra small fridge) we are now in the 325 kWH per month range. Still good (average around my area for a similar home is probably 600 kWH per month) but not really "off grid good".

Grid Tied solar systems now are available in the $5-$8 per Watt (turnkey installed) and a similar off-grid system would probably be in the $10-$20 per Watt range.

Get yourself a Kill-a-Watt meter (good for checking individual appliances) and/or whole home type units (there are a lot of options today for whole home monitoring--worth a thread discussion in itself).

There is a big range of SHTF type options/ranges out there... There is two weeks after a major storm/earthquake (run the Air Conditioner or not type choices) until "help arrives"... Vs the 1-5+ years of things are just getting too crazy out there for me type planning.

In the end, solar pv power is not cheap and off grid power is not even close to cheap (although, it is better pricing than it ever has been before), you have a lot of decisions to make... Including how long you will be at your home address (larger solar systems are not portable).

-Bill

Seven · March 2011

Re: what batteries would you recommend?

I am a new guy too, but I will let you know what I discovered when I wanted to take my current house off-grid. The general rule of thumb I came up with was that if I took my electric bill and added three zeros to the figure, that would get me close to the cost of taking my house completely off grid. Not including permits or labor. If My electric bill was $325 and I ran all the numbers for usage and the amount of equipment needed to make that much energy from solar it would cost roughly $325,000.00. Also, I would need some land because there wasn't enough room on my roof or yard to put all the panels I needed.

Harsh reality right there. I will say something you are going to hear over and over and there is really no way to get around it. Conserve, conserve, conserve. Adding new windows, insulation, low wattage appliances, will be a much more cost effective way of reducing your energy needs than solar.

You mentioned a SHTF scenario. What you need to do is figure out exactly what you want to power. Ge a little kill-a-watt meter for about $30 and see what your equipment is drawing. Something like a chest freezer, fans, some small lights(hopefully LED), some radios, and maybe a TV and DVD player for entertainment come to mind. It will be a lot easier to desing a system for those few things, than your entire house. Plus you wouldn't have so much of an OPSEC violation.

Food for thought from one noob to another.

BTW... I am starting my own little system and the guys here have really helped me with the basics.

Photowhit · March 2011

Re: what batteries would you recommend?

sunpower wrote: »

i am probably the greenest/newest member here, so please be kind

i want to make a start on my long term goal "off the grid"

I take it you mean green as in new...

First point I make to anyone wanting an off grid system is... it's NOT Green. With just the fewest of exceptions, an off grid system will not be able to use as much power as it takes to create it's componets.

It can be cost effective, for me as there is a high user fee $25 before you buy any electric, and I use very little electric, max 2 Kw a day, 9 months of the year.

Or in the case of SHTF, you would want extra parts, and a very large battery, so the Guy with the biggest gun has a system that will be dependable for a while. If thing truely go south don't count on hanging onto your system.

I'll likely buy a forklift battery this year. I think this may make my system complete and reliable for 20 years, I have a spare charge controller, and 2 smaller ones for a 2nd failure, I have 2 - 24volt inverters, and if a battery cell dies, I'm capable of chopping the battery down to 12 volts, and I have a couple 12 volt inverters, what Idon't have is the easy ability to distill water, though I could make a steam system that would get pretty clean water.

I have a tiny house 12x16 with a sleeping loft, and a seperate 8x16 kitchen and bath house, to keep the cooking heat outside. I have @2000 watt array, 1800 watt inverter, think a single 15 amp cuircut, I do run a window AC (cabin has 6" insulated walls.) I think you could put together my system today for @10K with a fork lift battery. I think that is about what it has cost me with the tax credit and savings of $2000 from careful shopping (1800 watt prosine inverter $350 delivered, Power center $200 includes all fusing and a charge controller,...) I was able to do all the work my self, this is likely imposible in Florida due to regulations.

Hope this at least gives you some ideas, as with any system everything starts with your need/system demands.

icarus · March 2011

Re: what batteries would you recommend?

Off grid, battery based systems come at twice the cost per watt, with half the efficiency as a grid tie system, leading to energy costs ~ 4 times that of grid tie, already more expensive than the grid exclusive of subsidy.

The grid is your best friend if your mission is to be green. If you are worried about end of the world scenarios, then all bets are off. Energy costs are going to go up regardless, so installing PV now will, to some limited extent can buffer you from some of that cost increase.

Good luck and welcome to the forum,

Tony

solarix · March 2011

Re: what batteries would you recommend?

I'd say the levelized cost of a retail grid tie system is under $.25/kwh and off-grid is twice that. However, for someone who really is off grid - far from utility power, they almost certainly saved so much on purchasing land that the savings should buy a very nice solar system. Thinks solar is expensive? Try paying your average utility to extend their power poles even a fraction of a mile.

oil pan 4 · March 2011

Re: what batteries would you recommend?

If you want power for SHTF I would say get a diesel generator first.
Then pick up Solar panels, power inverters, a battery charger and a fork lift batt.
I would say get a brand new battery with out acid in it, that way the battery will have infinite shelf life and its life will start the day you pour the acid in and start using it.

You can get a diesel gen set quick, easy and its all one assembly, easy to move and will work when ever you need it. The solar power system will be more for long term light loads.

My idea for SHTF is run to be able to run saws, lights, welders, air compressors, and other power tools to clean up and rebuild.

BB. · March 2011

Re: what batteries would you recommend?

I would confirm with the battery mfg to see if their dry charged battery has anything longer than a couple year shelf life.

-Bill

techntrek · March 2011

Re: what batteries would you recommend?

oil pan 4 wrote: »

If you want power for SHTF I would say get a diesel generator first.

Only if he can also store a year's worth of fuel. Gensets aren't good for SHTF, only really good for a few pieces of dirt on the fan (like a week of no power after a hurricane).

I also don't recommend diesel for the variable loads you find in a home, since most of the time you only need a few hundred watts, which PV is much better suited for, or a small gas genset. If you size a diesel genset to handle the peak loads of a house it will wet stack from running a few hundred watts most of the time. It would be fine for a fixed load like charging batteries or running a well pump, though.

hillbilly · March 2011

Re: what batteries would you recommend?

In terms of SHTF thinking, I'd say that a propane generator coupled with propane fridge and stove (and a BIG tank) would likely be a bit more reliable than a gas or diesel generator. PV would also be theoretically more reliable for smaller amounts of power. I suppose it really comes down to just how bad you're thinking things could get. I mean really, if the whole grid came down for an extended period of time, I'd shudder to think of what all the ramifications could mean.

As for batteries, I'd say that the T-105 types are a very good starting point and dollar for dollar, they're pretty hard to beat. If you're really thinking about possible long term reliability, then I'd start looking at something more like the Hawker, Crown, Solar One type industrial batteries, or perhaps the very large Surrette (5000 series) batteries. Be sure that you're seated when you start crunching the numbers on what it would cost to have an ample power reserve with those type batteries; they're NOT cheap, but at least in theory they should last for a very long time if taken care of.

mikeo · March 2011

Re: what batteries would you recommend?

If you want power for SHTF I would say get a diesel generator first.

I have another take on looking at solar as future survival investment. First learn as much as you can. Second plan on downsizing now, move to the low rent district(usually rural), get or build a house only big as you really need, which is not what most people have or want. Lean all about conservation, gardening, canning. Buy very energy efficient fridge and freezer. Power these with solar full time with a small system. Heat and cook with wood or gas, and solar thermal. Develop your own water supply system. Buy taking this approach now, you can afford a small PV solar system with a backup generator and be covered for both small and large outages while still connected to the grid and enjoying cheap grid power as long as it lasts. Also the money you will save over the years with this approach will make you better prepared for retirement, lower your bills significantly and make you feel better even if the SHTF scenario never happens.

what batteries would you recommend?

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