Solar enthusiast from Virginia. Working on building a system so I can go off grid. Trying to lead a self sufficient life in a nice rural setting. Thanks for the forum.

Off grid? I hope you are willing to pay 10 to 30 times more for power, and can could careless about environmental issues.

__________________
Dereck, PE, MSEE
Moderator

I use little power now and am searching for ways to improve my usage. I don't mind paying more considering) 1. I own it and 2. When grid power goes down, I'm out.

What environmental issues do you speak of? I thought solar was green?

Not if you use batteries. You will never generate more power than it takes to make the panels, equipment, and especially the batteries you will be replacing every 3 to 5 years. Grid tied systems can have an EROI, but not off-grid battery systems.

__________________
Dereck, PE, MSEE
Moderator

I see, though, I am looking at AGM batteries that claim to have a 10 year life.

Some of our batteries are more than 10 years old and our solar/wind system has worked just fine for 18 years.

What sort of things do you want to power vasurvivalist ?

__________________
Our permaculture smallholding, off-grid, house building BLOG

You just paid 3 times more for pro-rated warranty, and it does not change the EROI equation. Sure batteries can be made to last 10 years, but they will not have the rated capacity if cycled daily or deeply.

Battery systems have their place where commercial power is not available or feasible. But there is no economic or environmental justification you can come up with, the math will just not work.

For example just using battery cost alone, nothing else like shipping, labor or disposal cost. If you want to use 5 Kwh per day comes out to 55-cents per day if purchased from the POCO at 11.2 cents per Kwh national average. Stretch that out $16.77 per month, $201.30 per year, $1006.50 for 5 years, $2013 for 10 years.

To provide 5 Kwh per day using batteries will require 25 Kwh capacity for a 20% DOD 5 year life or 50Kwh for 10% DOD 10 year life. A 10 year battery will cost you $150 per Kwh, so $150 x 25 = $3750 and last 5 to 7 years discharged 20% DOD cycle. To get 10 years double the cost to $7500 for 10 years of service. Just in battery cost alone you are paying 3.72 times more for power just in battery cost alone. Now add in all the real cost of solar panels, charge controllers, inverters, shipping, labor, materials, disposal fees,, shipping, and failures and you get the idea. It is a loosing game financially using batteries if given the choice.

__________________
Dereck, PE, MSEE
Moderator

Sunking,

Thank you for the math, however, it is more than just what something costs. As I said before, I am a self sufficient type of person that does not like to rely on others to provide things, especially power. If I have to invest the money into it, I will. I live in a rural area and our power goes down frequently. I also grow most of my own food and hunt. It's all about relying on myself to provide.

Good to hear your system has had a long life. Not going to powering much really, Refrigerator (12 volt), small microwave, maybe a window A/C unit, some 12 volt lights. Most appliances I will be purchasing will be 12 volts (coffeemaker, blender, etc..). I will design the system to be large enough to handle what I need to do. Money is no problem.

vasurvivalist sorry I did not mean to offend you, just making sure you know some facts before jumping in.

With that said I will be happy to help you out in a design. Here is what you need to do, or more what any designer will need to know:

• How many Watt-Hours per day will require.
• Location like a city state or zip code.
• System availability like 95% to 99%

You have to nail those questions first and be accurate or unpleasant surprises will be experienced.

__________________
Dereck, PE, MSEE
Moderator