03-23-2012, 10:11 AM
03-23-2012, 11:45 AM
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.
Originally Posted by TommyL
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.
03-23-2012, 12:02 PM
The grid tie system uses the grid as an immense battery in the case Sunking mentioned
03-23-2012, 01:25 PM
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.
Originally Posted by TommyL
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.
03-23-2012, 04:55 PM
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.
03-26-2012, 02:00 PM
Home Energy Back up System
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.
03-26-2012, 05:30 PM
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.
Originally Posted by Bigdo
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?
03-26-2012, 11:07 PM
BILLVON..If I was using 3600kwh a month I would be seriously worried.
03-26-2012, 11:45 PM
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.
Originally Posted by john p
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.)
03-26-2012, 11:51 PM
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.??