Anyone have any experience with Greenrock saltwater batteries?

We will be installing our solar system this year for the tire bale house we're building.
We have enough experience with lead acid batteries + solar to know that we won't be using them for our house.

We'll be getting Lithium or saltwater batteries.
Saltwater is the obvious eco choice, but the company is pretty new, has a tiny market share, and therefore little track record.  We're already aware that they are gigantic compared with lithium, just as safe and clean / no offgassing, etc., easy to have in the house (except for the size).  The lithium we are looking at has built-in battery management, and we don't know whether switching to saltwater means there are other controllers, etc. we'd also need beyond what we're planning for our system with lithium batteries (we do have a query in to Greenrock for that info).

Does anyone here have any experience with Greenrock batteries?  What insights can you share?

I'd also be interested in hearing how saltwater has panned out for you Aquion owners, although I have no idea how equivalent the Aquions would be to Greenrock...

And if there are any other companies out there offering saltwater batteries, by all means, school me!

I'm not interested in any hazing for swearing off of lead acid nor for considering lithium, but I am able to deal with it or ignore it if you can't help yourself !

Thanks in advance!

its basically the same technology as the aquion batteries. Bluesky energy tried to buy Aquion but it seems they are now out of bankruptcy protection and making batteries again so you could also research Aquions for reviews. The technology is interesting but the power density is low so your bank will be quite large. The big problem Aquion had was how fast each stack of batteries could give up amps or absorb them. It was really really low like in the 30 or 40 amp range. You had to gang up many strings of quite expensive batteries to get say 100 to 150 amps of draw at 24 volts for a 2.4 to 3.5 kW load not unusual when it comes to starting a deep well pump. Same thing if you wanted to have a larger array you needed too many strings of batteries to get the charge rate you wanted. I never used them just trouble shooted a battery bank for someone. I found that flooded lead acid beat them even factoring in midlife battery change out. That was 3 years ago maybe prices have changed.
Cheers,  David

Saltwater batteries sound a whole lot more like permaculture than my lead acid beasts. Every time I go to check and refill the water I feel like there has to be a better way!

You will burn more water on the saltwater then a lead acid.

Thanks for your input!  Good info to have.

I will say that Blue Sky / GreenRock has been super so far -- very communicative.  I am one of those nerds who asks a million detailed questions and then when I get answers I ask a million follow-up questions.  Our email thread already has 13 detailed, informative messages in it, and it just started Sunday night!  (36 hours ago, and yes, their first reply to me came Sunday night)

They are between models... they are adding battery management to each battery stack; the new version should be out early next year, but in the meantime they are not selling any more of the old version.   Bummer for our timing, since we'd like to get up and running this year not only because we need power at our construction site, but also for the tax credit.

Well, they are willing to sell us two Discover lithium batteries, and then swap them for 8 of their saltwater batteries whenever they are available, for no additional fee!  (The price tag is just a tad bit more than lithium for a generously bigger battery bank to hopefully have similar performance).  It is true that the big footprint is not lost on us -- in our little house, it will be a space hog compared to lithium.  We were originally thinking lead acid when we designed the utility room, though, so we should be able to do it.

They are also writing us a quote for a complete turnkey system including panels and everything else you need (inverters, charge controllers, etc etc).

The other vendor we are looking at is Wholesale Solar -- with them also we are going for a turnkey system (including backup generator).  We could also do a Wholesale Solar all-but-batteries kit, and get the batteries from BlueSky (lithium for starters, swapped out for saltwater when available). We are normally DIYers, but have way enough DIY on our plate at the moment, in the middle of a house build, finishing up our earlier greenhouse build, farming, and just managing day-to-day life living outside.

And we thought we were retired.

So we are OK with delegating solar system design and detail planning to a vendor!  We'll still have to pull permits, install the system, arrange inspections, etc.  That's enough.

Any input on wholesale solar would be welcome.  Or input on Heliene panels, Schneider inverter...

I have still not been able to find any info on buying Aquion batteries currently.  I've heard they are available overseas, and I did find 2 vendor sites that mention them (https://www.solar-electric.com/aquion-energy-batteries and i didn't record the other) but neither had them for sale on their site, and I have calls in to both to see if they actually are selling them (solar-electric just said no, haven't sold them since they went bankrupt).  The Aquion site itself does not seem to be working.  If anyone has a link to some place where you can buy Aquion, I'd be interested.  Also, if anyone has any comparison between Aquion and GreenRock batteries, I'd love to hear that too.  In the meantime, I am pretty impressed with Blue Sky / GreenRock.  They have been selling GreenRock batteries in the US for four years.

Thanks again -- I'll shoot off the 14th email with the questions raised by David!

Blue Sky response:

Those are great questions.  First, there is no 'burning' of the saltwater electrolyte.  They are sealed and never require any maintenance.  


As I mentioned in a previous mail, our batteries are 500W each, continuous power, so that particular comment is fairly accurate.  3-4 of our stacks match the capacity of one Discover (~7.2 kWhs).  But that one Discover can handle load of 7kW (if your inverter is that large), which will cover a lot of surges!  3-4 of our Saltwater batteries want to see about 1.5-2.0kW continuous charging/discharging.  8 Saltwater will want to see roughly 4kW.  Your 2 Discovers will not flinch at loads up to 14kW.  Our saltwater (and Aquion) are 48V batteries with a continuous charge / discharge of roughly 10amps (~500W).  They can surge up to 20amps for a few seconds.  

Love their fast and thorough response.  Not sure my hub will love the less fast and less thorough response of the batteries, though...

Do you know -- if we have a backup generator, does this just mean that with power surges (well pump, power tools, etc), if we overtax the batteries, the whole house backup generator will kick in?  Or is it going to be a pain in the neck when we get big surges, with shutdowns & reset etc?

Kimi Iszikala wrote:Blue Sky response:

Those are great questions.  First, there is no 'burning' of the saltwater electrolyte.  They are sealed and never require any maintenance.  


As I mentioned in a previous mail, our batteries are 500W each, continuous power, so that particular comment is fairly accurate.  3-4 of our stacks match the capacity of one Discover (~7.2 kWhs).  But that one Discover can handle load of 7kW (if your inverter is that large), which will cover a lot of surges!  3-4 of our Saltwater batteries want to see about 1.5-2.0kW continuous charging/discharging.  8 Saltwater will want to see roughly 4kW.  Your 2 Discovers will not flinch at loads up to 14kW.  Our saltwater (and Aquion) are 48V batteries with a continuous charge / discharge of roughly 10amps (~500W).  They can surge up to 20amps for a few seconds.  

Love their fast and thorough response.  Not sure my hub will love the less fast and less thorough response of the batteries, though...

Do you know -- if we have a backup generator, does this just mean that with power surges (well pump, power tools, etc), if we overtax the batteries, the whole house backup generator will kick in?  Or is it going to be a pain in the neck when we get big surges, with shutdowns & reset etc?

that is the most of it. So if you overtax the batteries the voltage will crash and the inverter will reset. Good to know about the electrolyte learn something everyday..

So I ran our choices by our local solar nonprofit that helps folks get up & running with solar.

He mentioned an electronic device that will lower the surge on motors so they are less likely to trip the inverter.  But he didn't know much about that -- they are mostly helping folks get started with small, simpler systems.

Does anyone know about that?  Is that what an "inrush current limiter" is?

So far the links I've found are all highly technical and sound like they are for big industrial applications...

I think we may just end up going with lithiium rather than cobble up a bunch of stuff to throttle our motors to make the batteries sufficient -- but I think we ought to at least check out the options before deciding.  I do love the idea of the saltwater batteries, but don't want to spend the same $$ for a system that does not work for us...

FYI, we did decide to go with lithium -- Kilovault.
(I am always curious after reading threads like this to hear how it turned out, so thought I'd close the loop on this one...)