Got my solar power off-grid system up and running (finally)

[kahle]

25722573

I've been working on this for a long time and I finally got my solar power system all set up and functioning. I ended up designing it myself mostly because I couldn't find anyone that was willing to do much more than just sell me a package. I made the mistake of buying my Solar Panels back in 2007 when I first started thinking about this. That turned out to be a HUGE mistake because the price of PVs has dropped considerably since then. If I had waited until this year to buy them I would have paid 1/4 of what I did back then.

The good news is I found a 2000 Watt Pure-Sign Wave inverter on Amazon for only $340 bucks.

Anyway, I've never seen any kind of guide that would tell you the proper ratio between you PV watt size and your battery KWh size. I ended up with only 250 watts of PV and 5.4 kWh for a battery bank. In my case, I often only use the cabin on weekends so there is a long time for recovery. That's why I figured I could get away with this particular ratio. But some of the cabin kits I saw had even worse ratios than that.

I went with a 24v system because (1) I don't really have any need for any 12V DC takeoffs, and (2) doubling the voltage allowed me to use smaller wiring.

I got a 2000 Watt inverter even though my lighting load is pretty small. Maybe 300 watts total. But my occasional loads, a circular saw, a hair dryer, a vacuum cleaner or a waffle iron should run without an issue there. The inverter eats up about 50 watts of power just being on and maybe a smaller one would consume less. I'm not all that familiar with inverters. Maybe that's a big energy debt to pay for the small amount of power I actually need?

My charge controller can handle another 500 watts of PV if I want to add them later. But I'm just going to see how well this works first before I start to tinker.

Anyway, anybody want to critique my design, feel free.

Paul

[rreidnauer]

I've been working on this for a long time and I finally got my solar power system all set up and functioning. I ended up designing it myself mostly because I couldn't find anyone that was willing to do much more than just sell me a package. I made the mistake of buying my Solar Panels back in 2007 when I first started thinking about this. That turned out to be a HUGE mistake because the price of PVs has dropped considerably since then. If I had waited until this year to buy them I would have paid 1/4 of what I did back then.Yea. I made the very same mistake. Thought there was going to be a supply/demand issue when energy prices went nuts back then, and I thought I done real good at $4/watt. (LOL)


The good news is I found a 2000 Watt Pure-Sign Wave inverter on Amazon for only $340 bucks.

Anyway, I've never seen any kind of guide that would tell you the proper ratio between you PV watt size and your battery KWh size. I ended up with only 250 watts of PV and 5.4 kWh for a battery bank. In my case, I often only use the cabin on weekends so there is a long time for recovery. That's why I figured I could get away with this particular ratio. But some of the cabin kits I saw had even worse ratios than that.Really? Actually there is a standard, and I know I've even posted it on these forums several times. Anyhow, the best ratio is 20:1 (battery watt-hours to panel watts) It's basically figured by taking the top 25% of your battery bank's capacity, and figuring five hours to recharge that. However, the ratio gets smaller if you are using more power and/or figuring multiple 'non-charging' days. A lower ratio isn't harmful, just inefficient.


I went with a 24v system because (1) I don't really have any need for any 12V DC takeoffs, and (2) doubling the voltage allowed me to use smaller wiring.

I got a 2000 Watt inverter even though my lighting load is pretty small. Maybe 300 watts total. But my occasional loads, a circular saw, a hair dryer, a vacuum cleaner or a waffle iron should run without an issue there. The inverter eats up about 50 watts of power just being on and maybe a smaller one would consume less. I'm not all that familiar with inverters. Maybe that's a big energy debt to pay for the small amount of power I actually need?Using a modified wave inverter is way more efficient on standby power usage. It's what I use in my RV right now, since I don't have any AC motors that need to be driven. (the only real need for pure sine wave) You may want to consider getting a second inverter to run the lighting and resistive loads, and save the pure sine for your AC motor needs.


My charge controller can handle another 500 watts of PV if I want to add them later. But I'm just going to see how well this works first before I start to tinker.Usually charge controllers are rated in amps. What do you got? I STRONGLY recommend MPPT charge controllers. (that's a type, not a brand)


Anyway, anybody want to critique my design, feel free.

Paul

[rreidnauer]

Oh, and is that AC switch being used on DC?

[loghousenut]

Oh, and is that AC switch being used on DC?

I think that switch is on the AC side. I'm wondering if you couldn't bump up the wire size from battery to inverter. Not a long run but that is the side where less resistance really matters.

I can't chime in on the sine wave inverter thing. When we bought our inverter, we thought we were getting a bargain at $1 per watt for our 2,000 watt Trace square wave. I guess it has been a few years. By the way, that inverter and the expensive solar panels are still going strong in the bus after all those years.

[kahle]

Oh, and is that AC switch being used on DC?

I must confess that that standard light switch is the one I use to isolate the PV array from the rest. I figured it wouldn't matter much since it's only a 10 amp load. Did I figure wrong?

[rreidnauer]

I thought so. Yes, it could come back to haunt you. DC can carry an arc quite easily when opening contacts. And in an AC only rated switch, the open contact gap is small, and opens relatively slow, which allows a DC arc to burn the contacts. The main time you'd do damage, is turning the switch off when the panels are in full sunlight. Eventually, the switch won't turn back on, or worse, could catch on fire with a sustained arc. (you'll hear the hiss of an arc in the switch)

[kahle]

The charge controller I got is http://www.theinverterstore.com/30-amp-solar-charge-controller-12-24-volt.html# this one which does not specifically say it is MPPT but from the description, I figured that it was the same thing. This is rated at 30 amps.

The reason I used the AC switch is that I didn't see any DC switches listed anywhere. Can you point me to a supplier? Or better yet, an actual switch?
I'm not sure it makes much difference, I only use the switch when I'm working on the control panel and I'm hoping that part is done with for now.

Ron mentioned the size of the wires I have used between the battery and the inverter. I thought they looked small too. But those are the wires that came with the inverter so I figured they had to be sized correctly. No? Should I upgrade?

[loghousenut]

They are not the largest battery cables in the world. In the dark ages the folks over at Home Power Magazine always preached upsizing those inverter cables. Said it was cheap efficiency that lasted longer than the installer. We used 0000 size on our 2000w system but twice the length you have.

As for the AC switch, I thought Rod was talking about the master switch. When I built the 12 system in the bus some 30 years ago I put in mostly used 110v switches and they are still going strong. They don't work anymore but they look good.

Probably ought to either change it or eliminate it altogether. I'd feel safe with no switch there at all.

[rreidnauer]

That charge controller you have is PWM. (pulse width modulation) You won't get all the power available out of your panels, like you would with an MPPT. (maximum power point tracking) It's all in how they function, and I won't go into all that, but PWM will create panel performance losses of around 30%. (you will only get about 70% of the rated power of the panel) MPPT will have practically no losses. (in fact, I've seen slightly over 400 watts being extracted from my 350 watt array at one point!) But the real advantage isn't the performance loss advantage. It's the flexibility the controller provides. I can use the same controller to run a 12, 24, 36, 48, or 60 volt battery bank, and I can send any PV voltage from bank voltage up to 150 volts to the controller. The advantages being, it makes expanding the system easy, and your wire sizes can be much smaller and have lower loses at those high PV voltages. Granted, you will pay for that benefit.

The switch: I'd trade it out for a DC breaker instead.

As for wire size to the inverter, like LHN said, bigger is always better. I found the cheapest places to get heavy cables made up are at those battery warehouse store locations. But you don't have to abandon you existing cables either. You can always parallel on another of equal gauge.


I put in mostly used 110v switches and they are still going strong. They don't work anymore but they look good.I'm still trying to figure out what politician LHN is trying to mimic with that line.

[StressMan79]

Don't remember but I think ac switches are OK up to 50 volts dc.

[loghousenut]

Don't remember but I think ac switches are OK up to 50 volts dc.

Not that one.

[Longhare]

Congrats, Paul!

Just curious, what batteries did you go with?

[kahle]

OK, so now I feel stupid, yeah I remember being told to make sure I got an MPPT charge controller way back when. So, I'm shopping for one now for this little system and I find that there's a number of really cheap ones and some really expensive ones and they all say they do exactly the same thing. But now I'm suspicious. I only need to handle about 40 V max input and about 10 amps max output. Got any recommendations?

[kahle]

Ah Longhare. I went with 4 Full River DC224-6 AGM batteries. These are 6 volt 224 Ahr batteries but they aren't the flooded type. The AGM (Glass Matt) batteries won't freeze on me over the winter. My PV setup is out in an unheated garage up in the mountains and it gets durn cold up there at night. Years ago I actually froze a flooded lead-acid battery but that was probably more because I had let it discharge than an actual problem with the ambient temperature. Anyway, I wanted to avoid that issue tis time round. The batteries are connected in series to make one 24v battery.

[rreidnauer]

OK, so now I feel stupid, yeah I remember being told to make sure I got an MPPT charge controller way back when. So, I'm shopping for one now for this little system and I find that there's a number of really cheap ones and some really expensive ones and they all say they do exactly the same thing. But now I'm suspicious. I only need to handle about 40 V max input and about 10 amps max output. Got any recommendations?Yugo and Mercades say they do exactly the same thing too.

Recommendations? Think ahead. 40v in, 10a out . . . . . . . . . for now. What about in a year or two when you want to add panels and get more power?

I wouldn't rush out to buy an MPPT controller at this point, just so you have the best. See how your system performs for you for now.

BTW, AGM batteries can freeze too when left discharged, but other damage is done to the battery any time of the year by sulphation when left below 75% SOC for extended periods.

[hotshotrucking]

very interesting info, most I don't understand but aside from many who believe the grid will go down across the country which is a strong possibility just the shear cost of electricity at today's rate and what it will be lets just say 5 years down the road. I went online to read up on the cost of a system and pulled out my current bill and at the top in message it said they were requesting a rate increase. As many of you stated the cost of the panels has dropped, and there seem to be some tax breaks on purchases state & federal. If I retire or when I retire (approx 10 yrs) I just cant imagine spending 25% or more of my income to light my home so yes I'm going to research a solar system in hopes of enjoying my freedom.
I noticed the system that is rated for my current usage but what kind of life expectancy do you expect to get? the one I looked at has a 25-year reliability and warranty, and would be 32 260 watt solar panel system. I'm sure I could go with less but this system says it would more than cover me with 5 hours of average sun light each day. I'm going to continue to research the panels but you guy's that are on them up and running I'm sure have learned a lot the sites don't tell you.

[rreidnauer]

Stay away from thin film panels and short of a big hailstorm, the panels will probably outlast you. My solar panels are 25 years old and I have seen them produce 15% over rated power recently. A well cared for battery bank can last 20 to 25 years. (Edison batteries last indefinitely) Buying reputable brand name products would probably be the wise move.

[StressMan79]

Edison batteries have 2 major down sides.

1. Getting them is not easy.
1.5 most equipment is made to run on lead acid
2. This is bc ldac charges AND discharges @ around 2 v/cell. Charging nife cells occurs@1.7 v. Discharge happens @ 1.2.
A. You have to make a 12v inverter operate fron 10-22v, not 11-15.
B. You lose that delta v in efficiency. 1.2/1.7=70.6% right off the bat.

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[rreidnauer]

Yup, if you get hung up on efficiency, then you won't like the Nickle-Iron Edison batteries. They also experience more idle energy losses than Lead-acid, but as long as they provide the power needed, who cares? My panels are also lower efficiency compared to today's panels, but I really doesn't matter. All the efficiency factor means is they produce more wattage per area. All I care about is they produce the wattage they say they will, and that I have enough power for my needs.

The 12 volt argument is pretty mute, as any whole-house system would never be operated at that voltage. More likely 48 volts or higher, and with that, makes matching Edison cells to an inverter/charge controller that much easier.

[StressMan79]

Indeed. Except you pay for each watt you get, say $1000 assuming 100%, you'll need $1300 to run nife batteries.

And 12 volts was only an example. I have a 24v system. Cheap inverters and leds are available... any higher and you naad green energy products... read expensive

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[Timberwolf]

Edison batteries have 2 major down sides.

1. Getting them is not easy.
1.5 most equipment is made to run on lead acid
2. This is bc ldac charges AND discharges @ around 2 v/cell. Charging nife cells occurs@1.7 v. Discharge happens @ 1.2.
A. You have to make a 12v inverter operate fron 10-22v, not 11-15.
B. You lose that delta v in efficiency. 1.2/1.7=70.6% right off the bat.



This would be great... in ENGRISH!

[loghousenut]

Peter only speaks Gibberish... You get used to it and just kinda nod your head like you understand.










hahhhaw

[donjuedo]

This would be great... in ENGRISH!

I, Peter (donjuedo) can't speak for Peter (stressman79), but I can provide a little overview about that battery type (you may already know).

Thomas Edison invented a special type of battery using nickel and iron, and instead of acid, he put in potassium hydroxide, if I'm not mistaken (going from memory here). The symbol for nickel is Ni and the symbol for iron is Fe, so a nickel iron battery is often called a NiFe battery, as well as an Edison battery.

Stressman abbreviated because as "bc" and lead acid as "ldac", so that might have thrown you off a little.

NiFe batteries are available from ironedison.com, a US company sourced from China, IIRC. I also found a Chinese source, and the batteries look identical, except for the logo. They gave me a price quote, but I don't recall how it compared to Iron Edison pricing, mainly because I'm not ready to buy, yet.

My first choice for a charge controller is the same Outback model Rod has, but when I scoured the manual, it looked like the low voltage setting to shutdown (to protect batteries) is not low enough to make good use of NiFe batteries, despite a distributor claim to the contrary.

NiFe batteries can drain quite a bit lower than conventional lead acid, so in that way, store and deliver more energy than lead acid that seems the same size. Also, you can ruin a lead acid battery much more easily than a NiFe, and I'm sure I'm going to make mistakes.
:-/


Peter

[Little Eagle]

So i have a question that has been wondering through my head as i really know nothing of solar power, would i need to wire the home with with different wire for solar or can you use the same wire inside as if you were hooking to city power?

[donjuedo]

I have visited a home with 12 volt lighting built in, but that is very non-standard, and I would not recommend that.

It's best to wire the home normally, the solar power is delivered through what's called an inverter. Quite simply, it's an electronic box that takes in 12 volts DC, like car batteries charged by solar panels, and puts out 120 volts AC, like a normal home uses. It would connect to your home's wiring near the breaker panel.

It might look like this:

/------ 120 volts AC <-- inverter <-- 12 volts DC <-- battery bank <-- MPPT charger <-- solar panels
|
switch --> home wiring
|
\____120 volts AC <-- power grid

There are many options to consider, like wiring for 24 battery packs instead of 12. Both can work. Some folks use 48 volts, and that's fine, too.

You could plan to feed the grid with your solar power during the day, and use the grid at night. That's what my brother does, so there are no batteries.
You could go "off grid", and use batteries for power after the sun goes down. Batteries can be the most expensive part of a system.
You could combine options, and use batteries and connect to the grid.
You could throw in a generator to complicate things. OK, for back up, for various reasons.

[Little Eagle]

I have visited a home with 12 volt lighting built in, but that is very non-standard, and I would not recommend that.

It's best to wire the home normally, the solar power is delivered through what's called an inverter. Quite simply, it's an electronic box that takes in 12 volts DC, like car batteries charged by solar panels, and puts out 120 volts AC, like a normal home uses. It would connect to your home's wiring near the breaker panel.

It might look like this:

/------ 120 volts AC <-- inverter <-- 12 volts DC <-- battery bank <-- MPPT charger <-- solar panels
|
switch --> home wiring
|
\____120 volts AC <-- power grid

There are many options to consider, like wiring for 24 battery packs instead of 12. Both can work. Some folks use 48 volts, and that's fine, too.

You could plan to feed the grid with your solar power during the day, and use the grid at night. That's what my brother does, so there are no batteries.
You could go "off grid", and use batteries for power after the sun goes down. Batteries can be the most expensive part of a system.
You could combine options, and use batteries and connect to the grid.
You could throw in a generator to complicate things. OK, for back up, for various reasons.

Ah ok, being a trucker i have a inverter in my truck to run my crockpot and such so i know what you mean now. Good to know i can still run the wiring normally i was unsure about that part. Thank you for the advise.

[BoFuller]

I wired my house like a normal house and now I'm ready to install the solar. Currently I'm planning on 12 panels on the roof (235V) and either 16 or 24 Trojan L16RE-B (6V) batteries, then either one or two Outback 3648 Inverters. I did a worksheet and figured one inverter and 16 batteries would be enough until I factored in my water pump, then it looks like I need a second inverter and 8 more batteries..

[BoFuller]

Actually I'm sticking with the 16 batteries and single inverter. I exchanged my one hp water pump for a 1/2 hp unit.

[phorvath]

I agree that a grid-tied solar system is cheaper in that batteries can be eliminated. You can also either sell the excess power back or have your bill reduced. But I've read that it is wise to ask your utility serving your area property where the nearest pole is and how much it will cost to bring a power line into your property.
Like everyone else, I've been pricing everything and found that it will cost me about $7000 more to go completely off-grid compared to using a grid-tied system (assuming no charge to bring a power line in or minimal cost if the pole is right at the road by the property). I could be wrong. Of course the prices will change when I begin to build. Also, I do worry about having to replace batteries so I would buy those with the longest warranty period.
Phil

[phorvath]

Hello Loghousenut!
You seem to be the wisest here and I always appreciate your good advice. I can't make the class this year but hope to attend in May 1916 if the class is available.
Amazing, my family is in support and say, "go for it." Hopefully after I take the class I can travel to someone's build site and help there for the experience because I will probably need help too. If anyone's interested, I just found a great book by Henry A. Mercer titled Ancient Carpenters' Tools. Amazon.com $17 - $20. Describes log building tools (axes, hatchets, draw knives etc.). This would help if you are looking for old tools at flea markets, antique stores, etc.:cool:
Have a good day!
Phil (hello NSA!)

[edkemper]

I agree that a grid-tied solar system is cheaper in that batteries can be eliminated. You can also either sell the excess power back or have your bill reduced. But I've read that it is wise to ask your utility serving your area property where the nearest pole is and how much it will cost to bring a power line into your property.

Phil,

I can only speak of CA regs on grid tied systems. First, there is a customer charge that isn't eliminated by your production. Second, you can only sell what you use. Meaning, since you are not a "real" power company, you can only sell to the system that which you use. Anything you produce over what you use, they say think you for your excess production. Until that one item changes, we won't have the public replacing the produced power of (for instance) coal and hydroelectric production by homeowners. So it's not really a money maker for us.

Personally, I am hoping to go with my own battery bank and not be tied to a system that I can't get a zero cost or profit from being part of.

Welcome to the fold my friend.

[donjuedo]

Hello Loghousenut!
You seem to be the wisest here and I always appreciate your good advice. I can't make the class this year but hope to attend in May 1916 if the class is available.
Amazing, my family is in support and say, "go for it." Hopefully after I take the class I can travel to someone's build site and help there for the experience because I will probably need help too. If anyone's interested, I just found a great book by Henry A. Mercer titled Ancient Carpenters' Tools. Amazon.com $17 - $20. Describes log building tools (axes, hatchets, draw knives etc.). This would help if you are looking for old tools at flea markets, antique stores, etc.:cool:
Have a good day!
Phil (hello NSA!)

May 1916? Got a time machine? :D

You're off to a good start, planning on solar. Prices on panels keep coming down.

[loghousenut]

Hello Loghousenut!
You seem to be the wisest here and I always appreciate your good advice. I can't make the class this year but hope to attend in May 1916 if the class is available.
Amazing, my family is in support and say, "go for it." Hopefully after I take the class I can travel to someone's build site and help there for the experience because I will probably need help too. If anyone's interested, I just found a great book by Henry A. Mercer titled Ancient Carpenters' Tools. Amazon.com $17 - $20. Describes log building tools (axes, hatchets, draw knives etc.). This would help if you are looking for old tools at flea markets, antique stores, etc.:cool:
Have a good day!
Phil (hello NSA!)


You're a very perceptive fellow, Phil... In May of 1916 I was just getting situated with some of this wisdom.

My advice to you is to wait a year or so and take the class. Sooner if you can swing it but I say no hurry. After class you'll be welcome here at the LHN spread but don't expect much work happening. I'm slow and meticulated.

[phorvath]

Thanks Ed!
I definitely prefer the off-grid route. Don't know if it is okay on here to mention a vendor I found. I'll take a chance and say it is okay. I've priced everything at www.bluepacificsolar.com. They have the watt requirement inventory tool. I probably underestimated but I figured that I will need a 2000 W system (unless I find a "full time night woman"). They sell the solar panels, inverter etc. in kit form. The batteries are under a different tab. This is the only site I've found so far so I don't have another for price comparison. This site also has grid-tied solar kits. I will probably have two sets of eight 9-volt batteries (in series) connected in parallel. Also a Generac generator.
:cool:I think what you guys are talking about above will be useful. I'll also keep in touch with my electrician friends here at work.
Thanks for the advice!
Phil

[phorvath]

Hi Don!
I couldn't make it to class this year due to my Federal Theft Return and other expenses. But next year for sure. Will be retiring at age 70 (am 67 now) so I have time to collect all the tools after the class and purchase the land. I hope this can be in Montana. I've looked at the Michigan Upper Peninsula as well as the Superior bordering county of Wisconsin. But I always come back to Montana and the mountains.
Your from Pittsburgh, PA! I grew up just outside of Philadelphia.
Can't wait to take the class.
Phil:cool:

[phorvath]

Okay Great!
I'll keep coming back here.
Phil

[donjuedo]

Thanks Ed!
I definitely prefer the off-grid route. Don't know if it is okay on here to mention a vendor I found. I'll take a chance and say it is okay. I've priced everything at www.bluepacificsolar.com. They have the watt requirement inventory tool. I probably underestimated but I figured that I will need a 2000 W system (unless I find a "full time night woman"). They sell the solar panels, inverter etc. in kit form. The batteries are under a different tab. This is the only site I've found so far so I don't have another for price comparison. This site also has grid-tied solar kits. I will probably have two sets of eight 9-volt batteries (in series) connected in parallel. Also a Generac generator.
:cool:I think what you guys are talking about above will be useful. I'll also keep in touch with my electrician friends here at work.
Thanks for the advice!
Phil

Phil,

In order to procrastinate this afternoon, I visited the web site you listed, and made a spreadsheet to compare batteries' system cost. The public link is here:

https://docs.google.com/spreadsheets/d/1oCSzDWv61l0GEPIbOr4y2i_S0fUUeYjV_JvcW1Cs4SM/edit?usp=sharing

My assumptions are based on my usage in this part of the country, and how long I'd go before starting a generator. I have no laundry in this apartment, and wash dishes by hand. Heating and cooling costs do not show in my numbers. Everyone's needs are different, of course, but I'm hoping this spreadsheet will help folks size their own system and shop for the best battery deal.

If you find typos, please let me know.


Peter

[StressMan79]

Thanks Ed!
I definitely prefer the off-grid route. Don't know if it is okay on here to mention a vendor I found. I'll take a chance and say it is okay. I've priced everything at www.bluepacificsolar.com. They have the watt requirement inventory tool. I probably underestimated but I figured that I will need a 2000 W system (unless I find a "full time night woman"). They sell the solar panels, inverter etc. in kit form. The batteries are under a different tab. This is the only site I've found so far so I don't have another for price comparison. This site also has grid-tied solar kits. I will probably have two sets of eight 9-volt batteries (in series) connected in parallel. Also a Generac generator.
:cool:I think what you guys are talking about above will be useful. I'll also keep in touch with my electrician friends here at work.
Thanks for the advice!
Phil

9? Volt

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[rreidnauer]

Your from Pittsburgh, PA! I grew up just outside of Philadelphia.
Can't wait to take the class.
PhilThen I'm sure you know where I grew up, in Quakertown.

[BoFuller]

Hello Loghousenut!
You seem to be the wisest here and I always appreciate your good advice. I can't make the class this year but hope to attend in May 1916 if the class is available.
Amazing, my family is in support and say, "go for it." Hopefully after I take the class I can travel to someone's build site and help there for the experience because I will probably need help too. If anyone's interested, I just found a great book by Henry A. Mercer titled Ancient Carpenters' Tools. Amazon.com $17 - $20. Describes log building tools (axes, hatchets, draw knives etc.). This would help if you are looking for old tools at flea markets, antique stores, etc.:cool:
Have a good day!
Phil (hello NSA!)

LHN, Wisest? Boy have you been snookered.

[edkemper]

Hello Loghousenut! You seem to be the wisest here and I always appreciate your good advice. Phil (hello NSA!)

Is it possible you're from either Colorado or Washington? :rolleyes:

[rreidnauer]

LHN, Wisest? Boy have you been snookered.
It was a typo. He meant wiseassed.

[loghousenut]

Phil (phorvath) just PM'd me with his apologies... He meant w i d e s t.

[phorvath]

Hello donjuedo!
Thanks very much for this information. The batteries that I have looked at are Rolls (my first choice) followed by Trojan. I calculated that I will need 16 nine volt batteries. Hopefully I can live off-grid 100% with a complete solar system. I don't plan on having a lot of appliances. This will be a complete change in lifestyle and I am looking forward to it.
Have a great day!
Phil

[donjuedo]

Hello donjuedo!
Thanks very much for this information. The batteries that I have looked at are Rolls (my first choice) followed by Trojan. I calculated that I will need 16 nine volt batteries. Hopefully I can live off-grid 100% with a complete solar system. I don't plan on having a lot of appliances. This will be a complete change in lifestyle and I am looking forward to it.
Have a great day!
Phil

I'm glad it was useful. But now I'm curious about your need. You said you need 9 volt batteries but all the batteries offered have even voltages, not odd. An inverter won't care, but a charger or BMS would.


Peter

[rawson]

Anyone checked into the latest Tesla whole home battery yet, pros or cons?

[donjuedo]

I did read a little. The 10 KWH model is not meant for daily discharge, but the 7 KWH model is. It just happens to be the energy I use in an average day, without heating or cooling. To be off-grid and last 3 days due to cloudy weather, I'd be OK with 7 units. That would cost just over 10 kilobucks. I will wait.

[marshall]

Did hear that Tesla isn't even making the batteries yet. Still in some sort of preliminary phase. At least that's what a solar company in Huntsville, AL told us when we inquired about solar.
I have been to several websites to price an off-grid solar system and have gotten wildly different estimates.
The only main appliances that will run will be fridge and separate freezer. The rest is lights(led), ceiling fans, and other small appliances. The well will be on a separate/dedicated solar system.

I was just curious about what was the "norm" with those who have off-grid solar? I know it varies wildly, but I'm trying to get an idea of what is reasonable and what sounds outlandish.

Everyone here sounds like they know way more than I do so I just thought I might get some friendly advice?

Thanks!

[Little Eagle]

I found this that said they would be deliveries this summer, may not be THIS summer but im not sure.

http://www.teslamotors.com/powerwall

[pietro]

Has anyone looked at lithium-ion batteries? I'm thinking of combining a few LiFePO4 ones and some supercapacitors.

[edkemper]

Awesome batteries. Had ten (12v) in the space of two normal wheelchair batteries in my powerchair. Crazy expensive short term. Drove further, by far faster because of the steady juice and lasted for years. Could run them down like your laptop battery and then get a full charge in no time. Not sure of practicality due to the expensive nature of those high tech batteries.

[donjuedo]

I have not, but would be interested in how they compare. Specifically, I like to measure cost, and not just for one battery. That's because batteries are different, so cost per battery comparisons still amount to comparing apples and oranges.

So I figure out kilowatts-hours (energy) one battery delivers from full charge to "empty" (proper discharge level, not run down to 0 volts).

I also assume the battery will need replacement at the end of the warranty period. That's far from perfect, I know, but two things are important about that assumption: battery manufacturers generally lie about the same (AFAIK), and batteries surely don't last forever. (NiFe would likely last past my "expiration date", life expectancy, but I still do that math).

My measure, then, is dollars/KWH/year. I wish all battery manufacturers would advertise their batteries with my measure, for easy comparison.


Peter