LiFePO4 - The future for off-grid battery banks?

[TommyL]

JOSCO yes standard adjustable output voltage PWM CHARGER..
Here is a repeat of that post explaining all..

IF anyone is interested this is how I have set up 3 x100ahr LiFePo4 batteries for charging by solar and for use with MSW inverter..
Im not claiming this is the correct way or even the best way to do it,, But dont tell me it wont work as all 3 systems been in use over 2 years now almost 3 years with NO PROBLEMS
Charger a 30a PWP 12v charger set to output 14.8v with no equalization..
Battery cell over charging 1x 3.9V 1watt zenner diode and 1x10ohm resistor across each cell
One low voltage sensor set to disconnect the inverter and anything else connected to the battery pack at 10v
Facts as found out the expensive way by me are if you discharge a cell below about 2.2 v it will be destroyed even if done just one time only.
If you over charge above about 4.4v they have a very short life.
If you look at charts from the manufacturesr you find there is little power above 3.8v and it stays fairly constant until about 2.5v then hits a brick wall.
So use between those 2 voltages and all is well with the world.
I have never found a MSW inverter that has problems with operating between 15.5v and 10.5 v and that is the usual specs given by most MSW invereter manufacturers..

Thank you John!

Tommy L sends...

[TommyL]

Is there a good or great portable solar expandable Grid tie with battery charging system?

Tommy L sends...

[john p]

You cant have a portable gridtie system. Well not legally anyway in any country I know of. It has to all be installed to that areas regulations . Those ebay plug into wall socket grid tie inveters are to the best of my knowledge not legal anywhere and for good reasons.. example say you have a circuit that is rated for 20a and its already carrying 16a and you plug an inverter into it putting out 6a you are now opperating that circuit above its rating, now mabe overheating and a free fire.

[TommyL]

You cant have a portable gridtie system. Well not legally anyway in any country I know of. It has to all be installed to that areas regulations . Those ebay plug into wall socket grid tie inveters are to the best of my knowledge not legal anywhere and for good reasons.. example say you have a circuit that is rated for 20a and its already carrying 16a and you plug an inverter into it putting out 6a you are now opperating that circuit above its rating, now mabe overheating and a free fire.

Good Day John,

I thought from all my reading to date that the Grid Tie inverters energy would be used first.
The 16amps 1900watts Grid consumption would be reduced to 1200watts and the Grid Tie would
supplement the rest 6amps or 700watts.

Am I not understanding something correctly about the Grid Tie and how it works?

Tommy L sends....

[Sunking]

Am I not understanding something correctly about the Grid Tie and how it works?

Tommy L sends....

Maybe not. There is no way to control where the power goes.

If your systems is generating more power then your home uses, the excess goes out to your neighbors. If you are consuming more power than the system is generating, then the grid makes up for the shortage.

[TommyL]

Good day all.....
I'm not very good at this forum stuff, but I guess it's correct to stay on topic.

I will use Headway 38120HP (Red Cells) for an off grid system.

I've seen people using this in type of system while on Grid safely with a
Generator style pony panel. So you could collect sun all day and store into batteries,
run the house clocks and low consumption items while no one is home. Continue to
use during the evening until more consumption is required, then switch over to Grid power.

This way you get the best of both worlds, a back up without fuel and using solar to supplement

Any thoughts?

Tommy L sends....

[Sunking]

Good day all.....
I'm not very good at this forum stuff, but I guess it's correct to stay on topic.

I will use Headway 38120HP (Red Cells) for an off grid system.

I've seen people using this in type of system while on Grid safely with a
Generator style pony panel. So you could collect sun all day and store into batteries,
run the house clocks and low consumption items while no one is home. Continue to
use during the evening until more consumption is required, then switch over to Grid power.

This way you get the best of both worlds, a back up without fuel and using solar to supplement

Any thoughts?

Tommy L sends....

Tommy what you are talking about is a hybrid system. The problem is it doesn't work like you think. Battery power is extremely expensive, on the order of 10 to 20 times more than commercial power. It is pretty wasteful to spend that when you are already connected to the grid.

Better solution is plain ole grid tied system, where all that power during the day goes right out on the grid building up your credits, so when you come home you get to burn your credits and net 0 usage. If you want emergency power, install a generator using either LPG, NG, or diesel fuel. It is a lot less expensive, no limitations on power, and much better on the environment. Its a win-win no brainer.

[russ]

The grid tie system uses the grid as an immense battery in the case Sunking mentioned

[billvon]

Any thoughts?

Tommy L sends....

If you have grid available it is always better (=easier, cheaper, more efficient, cleaner) to use the grid as your battery. Store energy in it during the day, run on the grid at night. It's even good for the grid - you are feeding in during times of highest use and drawing from it during times of least use. If you live in an area that has frequent power outages, then float your batteries (they last longer that way) and use them only for backup.

You can get about 500 cycles out of your run of the mill batteries, probably 2000 out of your LiFePO4 batteries. For a typical house you're talking at least 12kwhr per day, so you would need 12,000 / (8ah * 3.2V) = 470 batteries, for a cost of around $10,000, for even one day of storage. They would have to be replaced every 5 years. So that's an additional $166 a month you'd have to pay to cycle through your batteries.

[TommyL]

This is all Awesome Information! This is awesome, but I'd like to do this on a small scale and expand. I've built my own house.
Yes, even pulled my own electrical permit. I will be having my final inspection this summer, so I will contact the Electrical Authority
and see if I require a different permit or if existing will cover it.

We have the new digital meter here. I'd like to find out more about that might be a benefit or not.

[Bigdo]

Home Energy Back up System

Hi Everyone,

I am new to solar and I am not that technical by any stretch. I have read some of your messages on this thread and it sounds like LiFePO4 has a higher initial cost but lower maintenance than lead acid batteries. I am currently in Nigeria: a country that has a lot of power outtages. I am looking for good home energy system to compliment our spastic grid here. I estimate a house load of 5kva. Please advise on the most cost effective brand of solar panels, inverter and battery pack to buy and their respective costs. Sorry moderator but I will like the names of companies and location so I can contact them for quotes to import. There are a few solar engineers I can employ to install for me. Deep cycle batteries and generators are very popular here and it has to to do with their relative cheapness. Thank you in advance.

[billvon]

I am new to solar and I am not that technical by any stretch. I have read some of your messages on this thread and it sounds like LiFePO4 has a higher initial cost but lower maintenance than lead acid batteries. I am currently in Nigeria: a country that has a lot of power outtages. I am looking for good home energy system to compliment our spastic grid here. I estimate a house load of 5kva. Please advise on the most cost effective brand of solar panels, inverter and battery pack to buy and their respective costs.

5kva is a power, not an energy, requirement. You have to measure the total energy used by the house over the course of a day. If it's an average, then you use about 120kwhr/day. If you get 5 hours of sun a day that's a 24kW system.

The absolute minimum price for the solar panels alone is about $1 a watt - so we are talking $24,000 for just the panels. And that's cheap chinese panels.

Is this within your price range?

[john p]

BILLVON..If I was using 3600kwh a month I would be seriously worried.

[billvon]

BILLVON..If I was using 3600kwh a month I would be seriously worried.

I installed an off-grid solar power system at an airport that used about 5000kwhr a month in the summer - a few air conditioners, two refrigerators, five structures with CF lighting, aircraft radios, PA etc. The solar power system (about 3kW STC DC) kept the system running when no one was there, basically just the answering machines and the refrigerators. During operations they ran a 10kW gasoline generator, and the two inverters (11kW worth) supplied the starting surges for the A/C. Battery bank was an 8s4p bank of T-105s for a total storage of about 42kWh.

They kept growing and eventually got sick of maintaining the batteries all the time, so bought two 50kW propane generators. Now they just run one all the time, and keep the other as a backup. (And since they have a few military contracts now, they can afford the fuel and service.)

[john p]

Sorry im not getting the connection? The guy was asking about a home install. I dont think his house in Nigeria is going to be in the same league as large industrial installation requirements are.??