Cost effectiveness of batteries

NorthGuy

When I was doing reasearch on batteries (about year and half ago), I made a comparison chart of different brands and types of the batteries to figure out which ones are better for me. I assumed that I would need to discharge the battery at 1KW output for 16 hours a day. Then I calculated depth of discharge and using manufacturer data found the cycle life of the battery at a corresponding depth of discharge. Knowing the number of cycles and overall price, I calculated the cost of storing one KWh.

Naturally, these numbers depend on the size of the bank because if you have more batteries your depth of discharge descreases.

I came up with the following ratings (from low to high price):

8 x Surrette 12CS11PS - $0.14/KWh
6 x Surrette 8CS17PS - $0.16/KWh
4 x Surrette 12CS11PS - $0.17/KWh
8 x Trojan IND13-6V - $0.17/KWh
16 x Trojan L16RE-B - $0.20/KWh
24 x Trojan L16RE-B - #0.21/KWh
12 x Surrette 12CS11PS - $0.21/KWh
16 x Trojan IND13-6V - $0.27/KWh
16 x Deca 8L16 Flooded - $0.35/KWh
16 x Deca 8G4D Gel - $0.54/KWh
20 x Deca 8G4D Gel - $0.55/KWh
12 x Deca 8G4D Gel - $0.60/KWh
24 x Deca 8L16 Flooded - $0.63/KWh

Looking at this table, there's no doubt that the most effective are think-plated heavy batteries such as Surrettes or Trojan IND. Small "cheap" batteries cost more, and sealed batteries are three times as expensive. Selecting the right kind of batteries seems to be a no-brainer. Watering batteries every two months and doing equalization twice a year is not the whole lot of maintenance to justify paying triple price for the sealed batteries. Right?

However, there's no substitute for real-life experience. If the flooded batteries are not "happy" with standard charging routine, and you need to do extra absorption time, or frequent equalizations etc. you would need an energy to do this. This energy must come at the time when batteries are fully charged and at the same time you must support all your loads. This is hard to get with RE, so most likely it will require some extra use of generator, which is very expensive. For me, an hour of generator time costs me $3.20 (in fuel and amortization cost) and if you count this cost towards battery maintenance, it adds $0.40 per KWh of stored energy. If I need two hours, it's $0.80/KWh, and for three hours you would need to add $1.20/KWh.

Factoring this in, the sealed batteries, which do not have any of these problems, do not seem expensive any more, and may be more cost effective.

Cariboocoot

Re: Cost effectiveness of batteries

Factoring this in, the sealed batteries, which do not have any of these problems, do not seem expensive any more, and may be more cost effective.

Except that it is really easy to destroy sealed batteries without ever getting a clue that something is wrong. They have all the same charging issues as flooded cells, except you can't check the specific gravity to find out if you are having those problems.

The cheap batteries which by your analysis seem to be expensive can in fact last as long as the expensive ones. And if you do destroy them early on you're not out so much money.

Then there's issue with being able to charge those batteries, as not all batteries charge alike. The Trojan and Surrettes want higher Voltage than the Dekas. Will your system be capable of charging them?

To compare battery value you have to pick comparable units; ones that will work interchangeably in the same system. That's not so easy to do. If you can it's a matter of comparing equivalent Watt hours for cost.

Matters of availability and local cost factor into it as well.

Not trying to be a pain; just pointing out a few caveats.

Eric L

Re: Cost effectiveness of batteries

However, there's no substitute for real-life experience. If the flooded batteries are not "happy" with standard charging routine, and you need to do extra absorption time, or frequent equalizations etc. you would need an energy to do this. This energy must come at the time when batteries are fully charged and at the same time you must support all your loads

Yes, one of the additional things to factor in is finding the most cost-effective panel-to-battery ratio for a given situation. I think with high-voltage panels now available at well under $1/watt, a much higher panel-to-battery ratio (watts : watt hours of capacity) than traditionally used can start to make economic sense. Having a higher ratio solves this particular problem while improving cloudy-day performance.

What ratio makes sense depends on many factors though; size of daytime loads, availability of opportunity loads, even the type and frequency of cloud cover can all make a difference.

Matters of availability and local cost factor into it as well.

This is a huge variable in my experience. I found cost differences between local distributors to be far greater than web price differences between types of batteries (AGM vs. FLA, e.g.).

BB.

Re: Cost effectiveness of batteries

Also, check the battery charging details... Many (most?) GEL batteries are rated at C/20 (5%) rate of charge maximum... A good off grid solar power system is probably a bit more usable and longer battery life with around a 10% rate of charge. A 5% rate of charge would require a 2x larger battery bank (at 2x or more the cost) vs a standard flooded cell configuration (assuming this is a daily use system rather than a emergency power / ups setup).

There is at least one European battery vendor that offers GEL with higher rates of charge--If you are still interested, I can look for the posts or one of the others here can give you some pointers.

-Bill

Photowhit

Re: Cost effectiveness of batteries

Hi Northguy,

I don't think you've been off grid long, or you have a very large genny. Equilizing is done when batteries are fully charged and takes very little current, so not much 'power' is needed. Also the type of equalizing your refering to is a 'maintainance equalizing' not even recomended for Trojan batteries, and can be done by your charge controller when it 'gets a chance' even older PWM charge controllers will do this.

If your comparing batteries by cost per Kwh you also have to take into account the longevity of the battery. If you'd like to do your calculations for my forklift battery, I'd bet it comes out pretty 'Shiny' 24V 800AmpHour Cost was $2525.

BTW- If your batteries "batteries are not "happy" with standard charging routine" your system isn't balance for your needs and your system should change once you've killed your batteries, if you can't adjust it by adding panels or reducing loads.

NorthGuy

Re: Cost effectiveness of batteries

Eric L wrote: »

Yes, one of the additional things to factor in is finding the most cost-effective panel-to-battery ratio for a given situation. I think with high-voltage panels now available at well under $1/watt, a much higher panel-to-battery ratio (watts : watt hours of capacity) than traditionally used can start to make economic sense. Having a higher ratio solves this particular problem while improving cloudy-day performance.

With cheap panels, if you get more panels, you can get away with less batteries. The panels will be producing something in the cloudy weather, thus eleminating the need to discharge the batteries.

For example, my panels produce electricity at $0.04/KWh. Now prices dropped even further, and it is probably $0.03/KWh. In comparison, an energy from generator costs me $0.65/KWh. Certainly, if you buy more panels and don't have enough batteries, the energy that they could've produced in sunny days will be waisted. But, even if I buy extra panels and waist 90% of their production, the rest 10% will cost you only $0.30/KWh, much cheaper than getting it from the generator. I have 6KW of panels now. I'm thinking about installing another 6KW this summer. With that amount of panels, I don't need a big battery bank, just enough to get me through the night. I got 673AH, and if it starts working, that's more than enough.

With such ratio, it should not be a problem to charge batteries, especially if you have less of them.

In winter, the situation changes. Since the day is short, and you need to baby your batteries with long absorptions/equalizations, you must run the generator no matter how much panels you have.

NorthGuy

Re: Cost effectiveness of batteries

Cariboocoot wrote: »

Except that it is really easy to destroy sealed batteries without ever getting a clue that something is wrong. They have all the same charging issues as flooded cells, except you can't check the specific gravity to find out if you are having those problems..

Perhaps, I could convert my flooded batteries into "sealed" ones if I didn't look inside

Cariboocoot wrote: »

The cheap batteries which by your analysis seem to be expensive can in fact last as long as the expensive ones.

For some reason, I think that these cheap batteries would have less charging problems because of the thin plates. At least, when I look on the Internet, people are having more problems with heavy-plated ones.

BB. wrote: »

There is at least one European battery vendor that offers GEL with higher rates of charge--If you are still interested, I can look for the posts or one of the others here can give you some pointers.

Thank you, Bill. I'll try to make it work with Trojans.

NorthGuy

Re: Cost effectiveness of batteries

Photowhit wrote: »

I don't think you've been off grid long, or you have a very large genny. Equilizing is done when batteries are fully charged and takes very little current, so not much 'power' is needed. Also the type of equalizing your refering to is a 'maintainance equalizing' not even recomended for Trojan batteries, and can be done by your charge controller when it 'gets a chance' even older PWM charge controllers will do this.

I'm still on the grid, and I will only disconnect when things are working than expected.

What you describe is what I thought it would be.

But, when the Trojan tech rep made me do a 20-hr equalization, that was a shoke to me. I simply cannot do this when I go off-grid. Neither can I do 4-hour absorptions that they recommend. Not without a generator anyway.

These are, certainly, extremes, and I will have to dial it down somehow, but it seems to me people are still having problems and have to do extra maintance, such as longer absorptions or mini-equalizations.

Photowhit wrote: »

If your comparing batteries by cost per Kwh you also have to take into account the longevity of the battery. If you'd like to do your calculations for my forklift battery, I'd bet it comes out pretty 'Shiny' 24V 800AmpHour Cost was $2525.

Would exchange my Trojans to couple of these any time.

Photowhit wrote: »

BTW- If your batteries "batteries are not "happy" with standard charging routine" your system isn't balance for your needs and your system should change once you've killed your batteries, if you can't adjust it by adding panels or reducing loads.

They are new batteries. I tried to charge them with solar, but then I discovered problems with them after 4 cycles. And they're off system now. I charge them every day with the grid, and do longer absorptions sometimes, and they're still not "happy".

Vic

Re: Cost effectiveness of batteries

Couple of things;

On a dark cloudy day, PV essentially produces nothing. So doubling the amount of PV will essentially produce 2 X nothing.

On a recent dark day, the 3.15 KW STC array produced 0.6 Kwh. On some, somewhat cloudy days the effect of doubling the PV size would make a larger difference, but ... still on dark days PV is of limited use for nominal-sized systems.

For off-grid systems, one will really need some form of generator - you MUST have something, regardless. It would not need to be 10 Kw, but genset cost will always be part of the system cost, even if just for the times when something important breaks.

In general, Sealed batts bring more problems to an off grid system than they solve. As noted, these batts are NOT batteries that you do not have to check the SG of, with no need to water. They ARE batteries that you can only infer (with some trouble) the SOC, and can only wonder if they have yet become ruined.

In my very direct personal experience with a number of Surrette batt banks, they do NOT require any special voltage settings for Absorption, or EQ. Many, many mfg's battereis would desire a higher Vabs in the Winter, just as an Opportunity recharge due to shorter days in many locations -- this is mostly dependant on DOD and typical RE power available. Nothing at all special, whatsoever, required for Surrettes IMHO.

And, NorthGuy, please do not give up on your current battery bank. IMHO, you must, must contact Trojan, or the dealer/distributor who sold the batts and have prescribe a recharge process that will work for your situation. It is quite possible that the maximum recommended Absorb voltage is too low for your situation.

Will not further derail this Thread ... You have a number of positive things in your favor; You seem to be a technical person, you care, and you are paying close attention to your batteries now, rather than a 2:00 AM when all the power is out (know that you are now on-grid, but this is the OG Topic). Good Luck! Vic

Vic

Re: Cost effectiveness of batteries

N G,

Our posts crossed ...

Well, recall that there has been no discussion of your loads, or on your desire to be off grid. Generally, Grid power is by far the least expensive of any power in the USA and Canada. Hawaii and parts of AK may be exceptions. Much of the extra cost of off grid systems is in the batteries.

The battery recharge times are essentially based on how much energy is removed from the batts, avaliable recharge power, and recharge efficiency, as well as loads on the system during recharge.

Conservation is the least expensive power that one will find, and it is especially important for off-grid systems, especially in northern climes.

Will post a few other thoughts in your Battery thread. Vic

NorthGuy

Re: Cost effectiveness of batteries

Vic wrote: »

Well, recall that there has been no discussion of your loads, or on your desire to be off grid. Generally, Grid power is by far the least expensive of any power in the USA and Canada. Hawaii and parts of AK may be exceptions. Much of the extra cost of off grid systems is in the batteries.

One of the reasons I'm going off-grid is because it's going to be about 30% cheaper than the grid power.

Vic wrote: »

On a dark cloudy day, PV essentially produces nothing. So doubling the amount of PV will essentially produce 2 X nothing.

On a recent dark day, the 3.15 KW STC array produced 0.6 Kwh. On some, somewhat cloudy days the effect of doubling the PV size would make a larger difference, but ... still on dark days PV is of limited use for nominal-sized systems.

My production is slightly better than this. I guess in Alberta it doesn't really get that cloudy. On a cloudy days, I get about 2KWh from my 6KW array. If the day ia cloudy, but not too dark, I get about 3KWh. My average load is 500W. With good timing, this would save me 0.5hr of generator run. In summer, when days are twice as long, I hope I would get 6KWh from my existing array, so doubling it will put me at 12KWh. With shorter night, it'll take care of 80-90% of my needs, and I may not need to run a generator on such days.

Vic wrote: »

For off-grid systems, one will really need some form of generator - you MUST have something, regardless. It would not need to be 10 Kw, but genset cost will always be part of the system cost, even if just for the times when something important breaks.

That's right. But the generator life is limited - the more you use, the faster it dies. And fuel is only getting more expensive. So, if you manage to shorten generator runs, it'll decrease your cost. In my situation, every hour that I save, decreases cost by $3.20.

Vic wrote: »

In my very direct personal experience with a number of Surrette batt banks, they do NOT require any special voltage settings for Absorption, or EQ. Many, many mfg's battereis would desire a higher Vabs in the Winter, just as an Opportunity recharge due to shorter days in many locations -- this is mostly dependant on DOD and typical RE power available. Nothing at all special, whatsoever, required for Surrettes IMHO.

That's good to know. May be I was looking for the posts that deal with problems with batteries, and got a wrong impression that you need to treat these batteries with extras to get them working. What kind of Surrettes do you have?

Vic

Re: Cost effectiveness of batteries

Hi NorthGuy,

First, your existing PV array would be considered large. Doubling it would make it very large in my book. So at about double the suize of the array where I am now your array should produce more than mine for similar illunimation, but the tilt of the PV will make some difference, although clouds are good diffusers.

Well, your grid power must be very very expensive. Batteries and electronics have finite lives, and those, too, need to be amortized (in addition to the genset).
Even with the reduction in the cost of PV modules, it is easy to make the case that off grid power can cost between $060 - $1.00 US/ Kwh consumed. So conservation pays off in a large way for off grid systems, and for GT systems where grid power is exhorbitant.

You should get a number of hours of good sun in the Summer, so at a reasonable elevation angle (tilt) of the PVs and no shading, you could easily see 20 - 30 kwh unless you are in a deep valley, etc. Very large PV arrays can easily be wasted, much of the year, when batteries are in Float, and you have run out of Opportunity loads. But know that your Winters can have very short solar days, even when the sun does shine.

Hope that you can get some meaningful data regarding just exactly what you need to do to get your battery bank in shape. This might well include higher than recommended Absorb voltage, until the bank behaves as Trojan says it should. The rated SG for these batteries is a bit of an odd-ball -- 1.260, but as such, one would expect the Vabs and Veq to be slightly lower than that of 1.265 SG batts.

The Surrettes here are 4KS25s -- 4 volt cells with a "rated" 20-hr capacity of 1350, but Surrette, like many other mfgs spec Capacity as if the batts use 1.280 SG electrolyte, which these, and most other Surrettes do not ... all a part of the specmanship game IMHO. So I say that these batts are about 1280 AH, a 5% reduction for the weaker electrolyte. These batteries have served well. Have one bad cell in one bank. This was caused by Floating this bank for a few years, with too few deepish cycles. Deep cycle batts really need to be cycled fairly frequently for good health, and so on.

Will look at the other Thread on these batts to refresh memory on what your daily loads are. Good Luck,

NorthGuy

Re: Cost effectiveness of batteries

Vic wrote: »

Well, your grid power must be very very expensive. Batteries and electronics have finite lives, and those, too, need to be amortized (in addition to the genset).
Even with the reduction in the cost of PV modules, it is easy to make the case that off grid power can cost between $060 - $1.00 US/ Kwh consumed. So conservation pays off in a large way for off grid systems, and for GT systems where grid power is exhorbitant.

I amortized all the costs over their projected lifespans (e.g. solar panels are good for 25 years, generator is good for 2000 hrs etc.) and my overall cost came up sligtly above $2K/year. This translates into $0.30/KWh. I've already decresed my consumption below these levels, so I use less KWh and actual cost per KWh will be higher. Since they de-regulted power here, the electric company can charge what they want, so I pay $3K/year (hope that is not for long). These are mostly fees of different sort, the electricity itself varies around $0.10/KWh. If their prices continue up, I may have to pay $5K in few years, but I'll be off-grid by then.

The battery bank is the most expensive part of this.

Vic wrote: »

The Surrettes here are 4KS25s -- 4 volt cells with a "rated" 20-hr capacity of 1350, but Surrette, like many other mfgs spec Capacity as if the batts use 1.280 SG electrolyte, which these, and most other Surrettes do not ... all a part of the specmanship game IMHO. So I say that these batts are about 1280 AH, a 5% reduction for the weaker electrolyte. These batteries have served well. Have one bad cell in one bank. This was caused by Floating this bank for a few years, with too few deepish cycles. Deep cycle batts really need to be cycled fairly frequently for good health, and so on.

These Surrettes were my first choice. I almost placed an order, but there were delivery problems, so I had to retreat and then decided to buy Trojans instead.

inetdog

Re: Cost effectiveness of batteries

NorthGuy wrote: »

I amortized all the costs over their projected lifespans (e.g. solar panels are good for 25 years, generator is good for 2000 hrs etc.) and my overall cost came up sligtly above $2K/year. This translates into $0.30/KWh.
The battery bank is the most expensive part of this.

Based on other calculations made by others on this and other forums, I have some problems with the $2K per year amortized cost and $0.30/KWh. I would guess that you are either being overly optimistic about your annual KWh production or are underestimating the lifetime cost of your batteries. I am very interested in seeing more of how you are calculating this. If your different battery size and DOD strategy plays a large part in this reduction, I definitely want to know more. :-)

BB.

Re: Cost effectiveness of batteries

NorthGuy wrote: »

Since they de-regulted power here, the electric company can charge what they want...

I am a bad boy--I really love the typo de-regulted power.

I am old enough to remember when the utilities (and the States) celebrated reliable and lots of power usage... Then the started making us feel guilty about using power, then campaigns to make even fell more guilty about wasting power (re-guilting). And now more re-reguilting and saving the polar bears and our children (hmm... not a good combination).

With fracking for oil and natural gas, we may be heading towards de-reguilting and beyond.

We also had de-regulation of power in California. Which really was more onerous regulation of power. In one year, it cost us over $25,000,000.000 in state bonds to bail out the (at least) two major power utilities in the state from bankruptcy. The costs to purchase electricity was de-regulated (and in fact, utilities where prohibited from contracting for electric power more than a few days in advance--No long term contracts allowed), but they were also prohibited from raising customer prices when the wholesale rates "ENRON'ed" to the sky.

At least we got a nice website on daily power usage in the State of California:

http://www.caiso.com/Pages/TodaysOutlook.aspx#SupplyandDemand



That was almost worth $25 billion dollars worth of 40 year state bonds.

-Bill

Photowhit

Re: Cost effectiveness of batteries

I too will suggest you check your math, I believe I have my costs down to about 26 cents a Kwh, and am in a unique situation where I don't need a battery bank large enough to surviv 3-4 days with out sun.

Did you include replacing electronics, inverter and charge controllers every 10 years, batteries every 10-15 years?

I'm only trying to provid a few hundred dollars worth of electric and your doing $2000, so I do question what's going on.

Here's my math;

It's going to be close to cost effective! or Off grid at 26 cents a KWh!

ChrisOlson

Re: Cost effectiveness of batteries

I have calculated that our batteries alone cost us close to 30 cents for every kWh we get out of the inverter to our loads. Getting total system cost down to 26 cents/kWh is very, very good.
--
Chris

inetdog

Re: Cost effectiveness of batteries

Photowhit wrote: »

I too will suggest you check your math, I believe I have my costs down to about 26 cents a Kwh, and am in a unique situation where I don't need a battery bank large enough to surviv 3-4 days with out sun.

Did you include replacing electronics, inverter and charge controllers every 10 years, batteries every 10-15 years?

I'm only trying to provid a few hundred dollars worth of electric and your doing $2000, so I do question what's going on.

Here's my math;

It's going to be close to cost effective! or Off grid at 26 cents a KWh!

I took a quick look at your math Photowit, and I am not ready to comment back in that thread, but one thing that stands out is that $20,000 now (or $10,000 now and $10,000 in 15 years) is not the same as $666/year over 30 years, even though the numbers are the same multiplied out.
That is why lottery winners who are offered $ 100 Million payed over 20 years versus $60 Million today have to think hard about which they want!

Also, you are assuming a 15 year battery life. That may be possible for you with good battery care, but it is more than most people will get. I suspect that even if you have a 15 year warranty on the batteries it will be both prorated and with strict enough requirements that it may not save you if they only last 10.

But even $0.52/KWh would be good enough for grid parity in Hawaii, and is an impressive achievement.

NorthGuy

Re: Cost effectiveness of batteries

I had a model, which calculated usage day-by-day. That's how I fugured sizes and lifespans.

Here's the components:

Panels 24 x $306 (255W) = $7,344. Yearly amortized cost at 0% interest over 25 years $294
Batteries 8 x $1075 = $8600. Yearly amortized cost over 13.1 years $656 (13.1 years come from actual usage put agains a published cycle life)
Generator $3500. Yearly amortized cost over 10 years $350 (it wouldn't use all hours within 10 years, but I capped at 10 years).
Generator fuel (NG) yearly cost $393
The balance $6000, amortized over 15 years (some things, like panel stand lasts longer, some, like Inverter, last shorter) $400.
Total - $2093/year.

That was an estimate that I made before buiding the system. Looking back I probably got things a little bit more expensive (the bigest example is solar stand took $2000 while I thought it would be $1000), however it wasn't far off.

The model had some mistakes. Namely, I hugely overestimated energy consumption (I planned for 7100KWh, but it's really below 5000KWh). I also, mismeasured a solar angle, so I underestimated the period of year where panel will be in a shade of three. I thought it would be no longer than a month, but it's longer. But both of these do not change the model drasticly.

Photowhit

Re: Cost effectiveness of batteries

ChrisOlson wrote: »

I have calculated that our batteries alone cost us close to 30 cents for every kWh we get out of the inverter to our loads. Getting total system cost down to 26 cents/kWh is very, very good.

I was lucky on some bargains and just cheap in other areas....

I do think forklift batteries are the way to go for cheapest energy per $ spent for larger systems, even if they require a bit more maintanance.

I'm more convinced when someone stated that Rolls (or maybe Trojan) required ordering in advance, because they made the battery to order, much like Golf cart batteries for small systems a battery that is mass produced can be done more cheaply.

That 24V 800 AmpHour battery was/is a new battery and price!

inetdog

Re: Cost effectiveness of batteries

NorthGuy wrote: »

The model had some mistakes. Namely, I hugely overestimated energy consumption (I planned for 7100KWh, but it's really below 5000KWh). I also, mismeasured a solar angle, so I underestimated the period of year where panel will be in a shade of three. I thought it would be no longer than a month, but it's longer. But both of these do not change the model drasticly.

Fortunately, those two mistakes partially cancel out. :-)

NorthGuy

Re: Cost effectiveness of batteries

BB. wrote: »

Also, check the battery charging details... Many (most?) GEL batteries are rated at C/20 (5%) rate of charge maximum... A good off grid solar power system is probably a bit more usable and longer battery life with around a 10% rate of charge. A 5% rate of charge would require a 2x larger battery bank (at 2x or more the cost) vs a standard flooded cell configuration (assuming this is a daily use system rather than a emergency power / ups setup).

Trojan recommends charging at C/5 for their Gel and AGM batteries.

Mangas

Re: Cost effectiveness of batteries

My experience, Trojans running 24/7 off grid with care will probably last about 7 or maybe 8 years.

For a best practices off grid system, believe me when I say a top end reliable and durable generator is absolutely mandatory. Not making sufficient investment in a good one with plenty of generating capacity for periods when it's 15 degrees out, snowing and the genny goes down will make you a believer.

Well designed off grid systems leave a lot of reserve capacity on the table (battery storage and generator output) in exchange for reliably meeting peak period requirements. My opinion is when designing a system conserve first and then build it around 140% of your expected consumption. Eventually, all of it will be used.

Photowhit

Re: Cost effectiveness of batteries

Mangas wrote: »

My experience, Trojans running 24/7 off grid with care will probably last about 7 or maybe 8 years.

That's like saying "a bag of groceries will last a week", There are different bags and different desities of foods. Trojan makes some very high capacity single cells that should last much longer (Some come with a 7 year warranty!)

Mangas wrote: »

For a best practices off grid system, believe me when I say a top end reliable and durable generator is absolutely mandatory. Not making sufficient investment in a good one with plenty of generating capacity for periods when it's 15 degrees out, snowing and the genny goes down will make you a believer.

Never had a genny in my 10 years off grid, so I haven't had to worry about the genny going down, I have conserved when it's been very cold outside where my batteries live and/or long periods of cloudy weather, but feel I'd rather conserve than have a genny for the handful of times I would have needed a genny.

Mangas wrote: »

Well designed off grid systems leave a lot of reserve capacity on the table (battery storage and generator output) in exchange for reliably meeting peak period requirements. My opinion is when designing a system conserve first and then build it around 140% of your expected consumption. Eventually, all of it will be used.

I really agree (other than the generator), having a slightly over built system can save lots of headaches!

Blackcherry04

Re: Cost effectiveness of batteries

Trojan Warranty, it works for them. Ever try charging and living off a 50 % battery bank and that must be a defect.

""The dollar amount of any pro-rated credit amount is to be based on the actual purchase price at time of original purchase, divided by the number of months in the warranty period then multiplying the sum by the remaining months in the warranty period:
A battery will not be considered failed, defective or unserviceable unless it fails to deliver 50% or more of its rated capacity (temperature corrected to 80°F) during the warranty period. A failed battery is not necessarily due to a manufacturing defect and must be verified.""

http://www.trojanbattery.com/pdf/TRJN0501_RESeriesLimtWarr.pdf

""The Manufacturer or its authorized representative may inspect the battery, which may require having the batteries sent for testing to Manufacturer or its authorized facility with freight prepaid by the customer.
Acceptance of the battery at the facility for testing does not mean that the Manufacturer will accept the warranty claim. Batteries still in serviceable condition or otherwise not covered by this Limited Warranty will be returned to the customer at the customer's expense and may be subject to a testing fee.""

Mangas

Re: Cost effectiveness of batteries

I guess it depends upon one's own lifestyle choices. Our investment is larger than most living off grid for several different reasons.

The batteries I was referring to are the newer L16 REBs'. I have 64 of them.

NorthGuy

Re: Cost effectiveness of batteries

I think everything depends on your goal.

My goal was to get the power that I need at a minimum possible cost. So I designed it that way, and that is why my electricity cost is supposed to be low.

If the cost wouldn't be my main concern, my system would be completely different.