Which battery is best for solar?

[Westbranch]

I really like the ~ 30 Lb weight of each 'cell' in the S line , 8 of them to a stack, one man job to move / install it!

[xsnrg]

If the specs are from engineering, and not from marketing, I have attached a simple spreadsheet to look at costs.  I also documented some assumptions and other thoughts.  Poke at it, let me know if I am off somewhere.  These look good if they deliver what they say.

[Westbranch]

you should split AGM and FLA, also add LiFePo4 that we know of at this time.  there are other Li chemistries but not on the open market at this time.    See 'Boston Power'

[xsnrg]

It would be nice to have them all listed, I agree.  I just have not done the research on other cell types yet, except for a little bit on AGM.  If you have the data for the other cells, the formulas should be able to be copied over directly into additional columns.  Feel free to add information and share it back.  Data always has assumptions, list those too if you have them.

[Westbranch]

I did some reading about the East Penn Ultra battery.  you can download the 2 white papers here:
http://www.ecoult.com/contact/?_cldee=ZXJpYy5qb2hhbnNlbkBzaGF3LmNh

I was especially impressed with the PSoC graph Fig 4 (SANDIA) on page 9 of the short version on the paper... 

Now that is more like what is needed for an O/G battery... downside is the weight...

[lasolargroup]

Hi,

I think Deep-cycle, lead-acid batteries are very good and i personally using for my solar product. so you can go for it

Link removed as it resembled advertising

[xsnrg]

@Halfcrazy, any word on your testing or additional thoughts?

@Westbranch, thanks for the links, have downloaded to see what they have to say.

[toothy]

Ryan

I am also quite curious.

I tried to send you a pm, I didn't want to poke you again on here about this, but it seems to have gotten lost in the netherworld.

Wade

[Halfcrazy]

Well so far so good the newer stacks they sell now are definitely better as far as surge capability. They are still softer than a Lead acid but its probably not an issue anymore. We have 6 stacks on an XW with a 3/4HP well pump and it starts that just fine. So far I am impressed but we have only been playing for a week on these new ones

[toothy]

Hello Again Ryan

After 11 hours of gen run today, including EQ, my brain is back on batteries.

No snow, no sun, little wind and rain for weeks on end at 35-45 degrees, remind me why I moved to AK?

I know it's not your department but..., why not add another module to the stack so it more closely resembles the DC input window for our inverters, your XW at I think 44-64 and mine at 42-68? I think I remember the early stacks started with 7 modules. 9 modules would put the voltage around 66V, so it would be closer to my DC high and a slight bit above yours.

Any new revelations? I hope your Aquions are forgotten in the corner, quietly doing their thing while being properly abused!

Thanks
Wade

[xsnrg]

I did some reading about the East Penn Ultra battery

Me too.  I reached out to East Penn, as well as to the only distributor they list on their website.  I actually received replies from both, so that was very nice.  What I found out is the battery is only being made for custom fits at this point, and larger distribution is probably not going to happen until at least Q3, which is a bummer as I am looking to switch to 48v shortly.  The battery has great specs for RE/solar purposes with the partial SOC expectation, and doesn't have any problem delivering current with the capacitance ability.  The technology has been in use since 2008 in quite a few laboratories and proving grounds with seemingly good results.  The actual specs on the cell though seem to be hard to find since they are not generally available yet. 

It looks good, but nearly any pre-release product does.

[xsnrg]

Ryan, given you are a month in, have the characteristics settled down at all?  I am asking because it is time for me to make a decision.  I have all the stuffs except cells for switching to 48v.

My questions are mostly around rate of charge and discharge.  They claim 480w continuous for a 48v nominal stack, which puts it at 10A.  A 24v stack then would be 240w at 10A.  Do they scale such?  Are you able to charge/discharge @50A on your 5 24v stacks continuously?

Given the entry price, 2 48v stacks at 1150 each plus shipping, I have to say I am leaning towards ole Pb Acid though.

[North of 56]

Ryan, given you are a month in, have the characteristics settled down at all?  I am asking because it is time for me to make a decision.  I have all the stuffs except cells for switching to 48v.

My questions are mostly around rate of charge and discharge.  They claim 480w continuous for a 48v nominal stack, which puts it at 10A.  A 24v stack then would be 240w at 10A.  Do they scale such?  Are you able to charge/discharge @50A on your 5 24v stacks continuously?

Given the entry price, 2 48v stacks at 1150 each plus shipping, I have to say I am leaning towards ole Pb Acid though.

I have read elsewhere that a price drop for the Aquion stacks is planned near the end of this year. Price is apparently going to drop from about $500/kwh to about $350/kwh if the company follows through?

Any word on the performance of the S20 stacks. They sound promising regarding rated cycle life, however, that may take years to prove out, especially if factoring in calendar life? $/kwh has me very interested. (10,000 cycles at an average 25% daily DOD works out to almost 30 years, not factoring in calendar life)

[xsnrg]

https://www.youtube.com/watch?v=FRYgRvtWTSA

During the video, they mention that the vendors are also monitoring things.... very cool.  2 M-pallets of Aquion.  I wonder if there is more information if one knows where to look?

[North of 56]

https://www.youtube.com/watch?v=FRYgRvtWTSA

During the video, they mention that the vendors are also monitoring things.... very cool.  2 M-pallets of Aquion.  I wonder if there is more information if one knows where to look?

After watching the video, it's interesting that they have set up the system with set points, so that the generator will come on line, when significant loads appear at the same time the battery SOC is relative low. It sounds like they are using the generator to handle the voltage sag of the AHI bank, at a lower SOC with loads.

I am seriously considering going the AHI route, and was thinking of going with a slightly smaller AHI stack quantity than originally planned. To deal with voltage sag, I would put in place a small LiFePo4 pack, that is set up to engage (ie put in parallel) with the AHI pack, thus, boosting the voltage and preventing the inverter from prematurely kicking out at lower SOC's.

For example, I would install say qty 10, S20 stacks into a 48 volt bank. This equates to roughly 20kwh of storage. If voltage of this pack under load drops below an adjustable preset level, I would engage the LiFePo4 pack, which would be sized to handle sub C currents with typical loads that come on. For handling a 3 to 4 kw load, a relatively small 100 ah pack @ 48 volts would suffice. The LiFePo4  pack would only engage when the load is present, and disengage shortly after. The relay used to connect the LFP pack to the main bank would also double as your LVD. And the relay for charging the LFP pack would double as your HVD, where charging could be redirected to the main pack from a separate smaller CC and panel setup.

I think that the two chemistry's could do very well together. Maybe it was meant to be? The only concern I have is it may be desirable when cutting in the LFP bank to do it softly rather than full on?