[RE-wrenches] sunny island and lithium

Tue Jul 15 12:49:21 PDT 2025

Hi  Mac and everyone 

Where I go with things these days is maximum reliability.  Having to use 3rd party products to communicate or making sure the firmware is up to date between multiple OEMS leads to all sorts of issues in my experience.  Now some of you are super tech savvy which makes this all fun and easy.  Me not so much. 
Fortress in the future recommends some update that doesn’t work with the SI which isn’t supported, not their problem, which it isn’t. 
This sunroof company goes belly up, removing the box, no comms.  

Given the level of communication now requested if not required between equipment, having OEM battery and inverter greatly keeps things simpler.  

I’ll keep you all updated.

thanks

jay

> On Jul 15, 2025, at 1:38 PM, Mac Lewis <maclewis1 at gmail.com> wrote:
> 
> Hi Jay,
> 
> The trick with a good lithium experience with Sunny Island is to have a way to give the Sunny Island the state of charge of the lithium battery.  The AC coupling works really well if it knows where the batteries are.  The built in algorithm for calculating SOC can't handle Lithium very accurately.  
> They do have a battery mode called Ext BMS that works via RS485 (I believe).  A company called New Sun Road ( https://newsunroad.com/contact/) has a microgrid box that was used by Blue Ion for a while to aggregate the BMS data and tell the Sunny Island what the state of charge is.   It may be worth calling them and talking with them about what battery you would like to integrate with.  With that, the Sunny Island works great.  I've had a quad stack humming along for about 4 years without an issue.
> 
> Economically, it still may make sense to ditch the Sunny Islands.
> 
> Good Luck!
> 
> On Tue, Jul 15, 2025 at 1:15 PM jay via RE-wrenches <re-wrenches at lists.re-wrenches.org <mailto:re-wrenches at lists.re-wrenches.org>> wrote:
>> Thanks William,
>> 
>> Yes it’s AC coupled which I neglected to include.  
>> 
>> Given how inexpensive the new inverter gear is, the age of the old stuff and seemingly the complication of integration I will propose replacement of both inverter and battery.  
>> 
>> thanks
>> 
>> jay
>> 
>> 
>> 
>> 
>> 
>>> On Jul 15, 2025, at 8:44 AM, William Miller via RE-wrenches <re-wrenches at lists.re-wrenches.org <mailto:re-wrenches at lists.re-wrenches.org>> wrote:
>>> 
>>> If the system is AC coupled I would suggest you dump the Sunny Islands immediately. 
>>> 
>>> We are soon going to wreck out 4 SIs and install 2 envy 12s. The SIs just would not work AC coupled to e-vault 18s. 
>>> 
>>> 
>>> William Miller
>>> Miller Solar.com
>>> 805-438-5600
>>> www.millersolar.com <http://www.millersolar.com/>
>>> 
>>> 
>>> On Tue, Jul 15, 2025 at 6:43 AM jay via RE-wrenches <re-wrenches at lists.re-wrenches.org <mailto:re-wrenches at lists.re-wrenches.org>> wrote:
>>>> HI All,
>>>> 
>>>> I might be inheriting a 12 yr old SI off grid system, that has a dying Absolyte battery.  
>>>> 
>>>> 
>>>> I know there have been some discussions on the SI and lithium. 
>>>> 
>>>> I’m just trying to understand what the options are with closed vs open loop, basically can it be done.  
>>>> 
>>>> If I do get the project, I will happily pay someone who’s done all the hard work for the education to tell me what the programming steps are.  
>>>> 
>>>> And at what point does it make sense to just remove the SI and install a AIO? 
>>>> 
>>>> thanks in advance.
>>>> 
>>>> jay
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> 
> 
> 
> --
> 
> 
> 
> Mac Lewis
> 
> "Yo solo sé que no sé nada." -Sócrates
> 

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