Couple questions on batteries and bank size.

[SunEagle]

But maybe less financial non-sense in HI. You want nice, you pay nice.

The high electric rates in Germany are beginning to make home battery system almost profitable.

But IMO it was the huge amount of RE installation subsidized by their government that made the electric rates triple.

[J.P.M.]

sharing the same end result- they both don't make financial sense.

But maybe less financial non-sense in HI. You want nice, you pay nice.

[max2k]

Good point. A Hawaii grid-zero system with batteries is a very different proposition than an "off grid" house in Tennessee.

sharing the same end result- they both don't make financial sense.

[SunEagle]

Not really. I hear that argument all the time, and I just shake my head because anyone that says that has not been to Hawaii. Sure electric prices are high in Hawaii. Now go to the store, gas station. market, or Batteries R US in Hawaii and you will quickly learn everything in Hawaii is outrageous prices, especially batteries.

That is why you find a way to import those batteries from the main land and not pay the high tariff.

[Sunking]

Actually, it is what I do in a remote area,

I stand corrected, thank you.

[Sunking]

Good point. A Hawaii grid-zero system with batteries is a very different proposition than an "off grid" house in Tennessee.

Not really. I hear that argument all the time, and I just shake my head because anyone that says that has not been to Hawaii. Sure electric prices are high in Hawaii. Now go to the store, gas station. market, or Batteries R US in Hawaii and you will quickly learn everything in Hawaii is outrageous prices, especially batteries.

[Mike90250]

Not quite, you can use the controller to limit battery charge current, and use the excess panel in the winter for better harvest on cloudy days

Sure you can. Is that what you do Miike? I did not think so...

Actually, it is what I do in a remote area, 1800w panels 24V system, 30A controller limit, way over paneled for summer. but not enough for winter, still had 3 LVD disconnects last winter.

[SunEagle]

Good point. A Hawaii grid-zero system with batteries is a very different proposition than an "off grid" house in Tennessee.

For that matter with the higher Tier rates in CA having something to reduce consumption from the POCO can make financial sense on a grid tie system.

Again that is as long as the battery has a long life or is low in cost. Otherwise people are just pissing away their money using batteries.

[jflorey2]

IMO it would be hard to make a generic statement or stickie post that batteries cost 5 to 10 times what a POCO will charge since the spread of electric goes from about $0.08/kWh to $0.50/kWh around the US and is sometimes changing every 6 months. In some places both the high cost of electricity and TOU rates almost make a battery financially possible. Of course that is considering battery cost is low enough or the life time is very long.

Good point. A Hawaii grid-zero system with batteries is a very different proposition than an "off grid" house in Tennessee.

[SunEagle]

A respectful suggestion to admin.: Maybe make the above, or something like it, a stickie to point to for newbies and/or those who believe that off grid/batteries, while certainly a possible option, is usually quite a costly option beyond most expectations.

IMO it would be hard to make a generic statement or stickie post that batteries cost 5 to 10 times what a POCO will charge since the spread of electric goes from about $0.08/kWh to $0.50/kWh around the US and is sometimes changing every 6 months.

In some places both the high cost of electricity and TOU rates almost make a battery financially possible. Of course that is considering battery cost is low enough or the life time is very long.

But I agree there is a major misconception by novices that power generated from a solar / battery system compared to the POCO will save them money. Probably for over 95% of the US that will not happen unless something major changes.

[J.P.M.]

I get it and understand. Let me steepen your learning curve and the most important thing you need to know because not many users on this forum want you to know this fact.

It is impossible for you to save any money on your electric bill using any form of battery power of any type. Nor is there any ecological benefit. Fact is anything you take off-grid is going to cost you 5 to 10 times more for electricity the rest of your life verse buying power from the utility and makes you a heavy polluter.

A good quality battery that last you 5 years will cost you $1000 to $1200 for each Kwh used daily. Now let's do some simple 5th grade math. You buy a $1000 battery and use 1 Kwh a day. After 5 years the battery is toast. So in that 5 years you used 1825 Kwh from that battery. Just in battery cost alone you ended up paying $1000 / 1826 Kwh = $0.55-Kwh. Where I lived a Kwh cost 7-cents, where you live more likely 10 to 15 cents per Kwh. So ask yourself why you want to pay and pollute more than you have to?

So if you are doing this to save money or lessen your environmental impact on Mother Earth, forget it, never going to happen. It means you have more money than you know what to do with and could care less about pollution and wasting resources. The media, activist, and government would never tell you that or want you to know. Kind of funny, so many people do not want others to know what the truth is because it is not politically correct.

So you need a 24 volt 600 to 900 AH battery to utilise your full panel wattage. A 24 volt 600 AH battery gives you roughly 3 Kwh of usable electricity per day, or about 30 to 50 cents worth of electricity per day. That battery will cost you $3000 to $4000 today and even more 3 to 5 years from now when it needs replaced. So you pay $3000 to $4000 for $900 worth of electricity.

That should help you decide what to do.

A respectful suggestion to admin.: Maybe make the above, or something like it, a stickie to point to for newbies and/or those who believe that off grid/batteries, while certainly a possible option, is usually quite a costly option beyond most expectations.

[Sunking]

Yes I get the question!! Sunking I was just making sure I understood what I was being told. First off I got the panels for basically nothing. I wasn't even going to mess with solar until I came across these panels so I got them first. The guy had a outback 80 that I bought but it had gotten wet in storage so it was shot. So then I bought what I thought would be the best I could afford.And now I'm trying to figure out what I need for batteries. ( Hence the question that I posted on here for help) I'm trying to learn and getting some good helpful replies. I'm not an electrical engineer or a electrician, just a guy trying to save a few bucks on my bill and learn a new hobby. hobby. Guess I should have went grid tie(micro inverters) but probably would have a some questions there also. Or just passed on the panels altogether!! Thanks for the help.

I get it and understand. Let me steepen your learning curve and the most important thing you need to know because not many users on this forum want you to know this fact.

It is impossible for you to save any money on your electric bill using any form of battery power of any type. Nor is there any ecological benefit. Fact is anything you take off-grid is going to cost you 5 to 10 times more for electricity the rest of your life verse buying power from the utility and makes you a heavy polluter.

A good quality battery that last you 5 years will cost you $1000 to $1200 for each Kwh used daily. Now let's do some simple 5th grade math. You buy a $1000 battery and use 1 Kwh a day. After 5 years the battery is toast. So in that 5 years you used 1825 Kwh from that battery. Just in battery cost alone you ended up paying $1000 / 1826 Kwh = $0.55-Kwh. Where I lived a Kwh cost 7-cents, where you live more likely 10 to 15 cents per Kwh. So ask yourself why you want to pay and pollute more than you have to?

So if you are doing this to save money or lessen your environmental impact on Mother Earth, forget it, never going to happen. It means you have more money than you know what to do with and could care less about pollution and wasting resources. The media, activist, and government would never tell you that or want you to know. Kind of funny, so many people do not want others to know what the truth is because it is not politically correct.

So you need a 24 volt 600 to 900 AH battery to utilise your full panel wattage. A 24 volt 600 AH battery gives you roughly 3 Kwh of usable electricity per day, or about 30 to 50 cents worth of electricity per day. That battery will cost you $3000 to $4000 today and even more 3 to 5 years from now when it needs replaced. So you pay $3000 to $4000 for $900 worth of electricity.

That should help you decide what to do.

[Stansbery]

Yes I get the question!! Sunking I was just making sure I understood what I was being told. First off I got the panels for basically nothing. I wasn't even going to mess with solar until I came across these panels so I got them first. The guy had a outback 80 that I bought but it had gotten wet in storage so it was shot. So then I bought what I thought would be the best I could afford.And now I'm trying to figure out what I need for batteries. ( Hence the question that I posted on here for help) I'm trying to learn and getting some good helpful replies. I'm not an electrical engineer or a electrician, just a guy trying to save a few bucks on my bill and learn a new hobby. hobby. Guess I should have went grid tie(micro inverters) but probably would have a some questions there also. Or just passed on the panels altogether!! Thanks for the help.

[Sunking]

Not quite, you can use the controller to limit battery charge current, and use the excess panel in the winter for better harvest on cloudy days

Sure you can. Is that what you do Miike?

I did not think so...

[Sunking]

Just making sure I'm getting this right. The smallest battery I can use is a 700ah battery?

Batteries have a minimum and maximum charge current range of C/12 to C/8 where C = the battery AH Capacity. OK you have a 1800 watt panel into a 24 volt battery produces up to 75 amps or let's just call it 70 amps. Using C/8 as the maximum curent gives you 70 amps x 8 hours = 560 AH. I originally I used 75 amps and C/10.

Now as has been stated, sure you can limit current with your controller.But if you do that then why the heck did you buy 1800 watts of panels if you are not going to use them? Do you understand that question?

If you limit current to 10 amps like you are now means you are only using 240 watts of your 1800 watt panel. You are pissing away 1600 watts of panels. You just should have bought a 200 watt panel and an inexpensive 15 amp controller and saved a couple of thousand dollars to go with your cheap batteries. Using a Charge Controller to limit current is pisspoor design and counter productive. If you want to limit current, do so by panel wattage.

So yeah you can use 4 x Trojan T-105's, and limit current to 30 amps. Doing so just screwed you out of 1100 watts of panels. It also means you lost 3 to 6 Kwh hours of usable energy in a day you will never recover or ever utilize. All because you do not have large enough batteries. If you cannot afford the batteries, then you cannot afford solar power