Small Off Grid Solar System ... I'm Taking the Solar Plunge

I missed something here. Are you storing the batteries inside the house? I agree that that is dangerous. The fumes alone from a leaking battery are very bad. I have also seen them explode at races, but that can happen other ways too, from overcharging being one of them.

From what I have read from others, they store batteries on an outside spot, next to a wall, covered over with a box. Even the old farm radio users often, but not always, did this. But if you have researched this and found it to be safe, have at it.

I should also add, you may want to keep a supply of baking soda on hand to counteract any leaking acid, if you ever have it happen.

warminmn wrote:I missed something here. Are you storing the batteries inside the house? I agree that that is dangerous. The fumes alone from a leaking battery are very bad. I have also seen them explode at races, but that can happen other ways too, from overcharging being one of them.

From what I have read from others, they store batteries on an outside spot, next to a wall, covered over with a box. Even the old farm radio users often, but not always, did this. But if you have researched this and found it to be safe, have at it.

One problem with storing them outside is that at -20 degrees outside they have only 35% of their advertised capacity. By +20 degrees they have about 63%, and by 40 degrees they have about 75%. Keeping them warm if stored outside is problematic and could be costly.

FLA batteries must be vented if kept in a confined area. AGM's have no such concern. With AGM's there is no requirement for venting, and also no possibility of spillage (in fact they are rated for acceptable use while laying on their side), etc...

Perhaps AGM is the way to go from the standpoint of ultimate safety and foolproofness.

Can you returned what you already purchased?

What's your expected ROI on the system? Now that you know more.

lsayre wrote:

warminmn wrote:I missed something here. Are you storing the batteries inside the house? I agree that that is dangerous. The fumes alone from a leaking battery are very bad. I have also seen them explode at races, but that can happen other ways too, from overcharging being one of them.

From what I have read from others, they store batteries on an outside spot, next to a wall, covered over with a box. Even the old farm radio users often, but not always, did this. But if you have researched this and found it to be safe, have at it.

One problem with storing them outside is that at -20 degrees outside they have only 35% of their advertised capacity. By +20 degrees they have about 63%, and by 40 degrees they have about 75%. Keeping them warm if stored outside is problematic and could be costly.

FLA batteries must be vented if kept in a confined area. AGM's have no such concern. With AGM's there is no requirement for venting, and also no possibility of spillage (in fact they are rated for acceptable use while laying on their side), etc...

Perhaps AGM is the way to go from the standpoint of ultimate safety and foolproofness.

So many people that are off grid live in warmer climates so I guess that is never a concern. That is quite a loss with the temperatures. I'm not familiar with AGM's at all. Can they still explode? Other than that, maybe they would be safe, but I'd sure do a lot of research before keeping any of them indoors. Your good at researching things.

They had a huge acid leak at work once from a holding tank. It is not a good situation to have.

davidmcbeth3 wrote:Can you returned what you already purchased?

What's your expected ROI on the system? Now that you know more.

I have not purchased any batteries yet. All of the other major components are already received or on order. I expect to generate 20% to 25% of the homes electricity demand from the solar panels, and thereby to be able to keep 20% to 25% of our electrical stuff up and running continuously in an electrical outage. Trying to keep the entire project below $3,000. How do you calculate an ROI for an emergency back-up generator?

Good point on the back up generator, which is kind of how you are going to use the solar.

I remember in the past you mentioned not wanting a propane tank, but another step in the future could be to add a propane freezer. That would free up more electric for other things, in case of long term outages, or for regular use. You could bury the tank so you didnt have to look at it. A propane cooking stove falls into the same catagory, but it wouldn't be right to replace a good working modern electric one.

lsayre wrote:
I have not purchased any batteries yet. All of the other major components are already received or on order. I expect to generate 20% to 25% of the homes electricity demand from the solar panels, and thereby to be able to keep 20% to 25% of our electrical stuff up and running continuously in an electrical outage. Trying to keep the entire project below $3,000. How do you calculate an ROI for an emergency back-up generator?

My emergency generator consists of : a) my car (hybrid) and b) a $100 2000 W inverter.
With my system there is no ROI ... I have used it for 2 weeks straight in one long power outage (used 5 gallons of gas to keep the refrig running and some lights)...and have used it on and off for a portable AC power source.

You are looking to get 80 KWhr/month from the system .. that's about 10 dollars worth of electricity ( @12 cents per kilowatt-hour ) a month.

But you are looking for a system that would cost $3000. To obtain $120/yr of PV generated electricity. Would take 25 years to the break even point....you may have a better choice with wind. Need avg speed of 17 MPH for that. And that's 25 yrs of perfect expectations. And this corresponds with the data I obtained from my review of people in my state who went through a PV program.

I can still remember when gasoline and diesel were suddenly unavailable in the 1970's. If the nations electrical grid ever goes down so will the availability of gasoline and diesel fuel and all other transportable fuels. But even in such a drastic situation as that a solar/battery system will provide electricity as long as the sun makes its usual appearances.

Besides, I said from the beginning that I primarily want it just to have a learning experience (I.E a fun hobby to toy around with).

lsayre wrote:I can still remember when gasoline and diesel were suddenly unavailable in the 1970's. If the nations electrical grid ever goes down so will the availability of gasoline and diesel fuel and all other transportable fuels. But even in such a drastic situation as that a solar/battery system will provide electricity as long as the sun makes its usual appearances.

Besides, I said from the beginning that I primarily want it just to have a learning experience (I.E a fun hobby to toy around with).

Its no worse than buying a new car and driving it for 6 months. Same $$$ loss. The way you like to play with numbers you will have a fun time with it. I'm a little jealous, although wind energy is more practical here.

I ordered my 40 AMP 24 Volt battery charger (rectifier, converter) today. When it arrives another piece of the puzzle will have been completed.

I read up on the new tesla system today. ...great system for 7400 dollars

johnjoseph wrote:I read up on the new tesla system today. ...great system for 7400 dollars

Too expensive for what they are giving you in my opinion. I detailed this within this thread somewhere. A longer lasting second tier Rolls/Surrette battery bank with the same effective capacity at list price would only cost $4,800. Either one is well beyond my means. I'll be at a tad more than $1,000 with my battery bank. And mine should provide 5KW of delivered electricity.

US Battery 420 AH hour x 6V. $245 per each before tax. $260.93 after tax. 4 x $260.93 = $1,043.72

4 x 6V x 420 AH x 0.50 = 5,040 usable watts.

That's 1/2 of the storage of the Tesla for 1/7 the cost. But these lower shelf "US Battery" batteries will only have 1/3 to 1/2 the life expectancy of the Tesla and I will need to maintain them routinely and faithfully.

I installed a stand alone solar system almost 15 years ago, and am still using the original batteries. They were very expensive, but with regular maintenance have seen little degradation in that time. I don't remember the brand, but they are 2 volt, 800 Ah, I have 12 in series. I was very careful during installation to oversize all the DC wiring to minimize line loss, and applied grease or Vaseline (I don't remember which) to the battery terminals to prevent corrosion. So far, so good. Make sure to use DC breakers and disconnects on the DC side. Good Luck!!

BurningRocks wrote:I installed a stand alone solar system almost 15 years ago, and am still using the original batteries. They were very expensive, but with regular maintenance have seen little degradation in that time. I don't remember the brand, but they are 2 volt, 800 Ah, I have 12 in series. I was very careful during installation to oversize all the DC wiring to minimize line loss, and applied grease or Vaseline (I don't remember which) to the battery terminals to prevent corrosion. So far, so good. Make sure to use DC breakers and disconnects on the DC side. Good Luck!!

Thanks! Wow, 15 years is a long time for batteries. I'll be glad if I get half of that. A good part of the secret to battery longevity seems to be in avoiding parallel wiring.