[RE-wrenches] off-grid AC coupling feasibility

[Jay]

I also worry about getting the system 
to 64 hz. 

That is hard on motors and might be the cause of the Light pulsing you’re seeing drake. 

Jay


> On Jul 31, 2022, at 10:08 AM, Drake Chamberlin via RE-wrenches <re-wrenches at lists.re-wrenches.org> wrote:
> 
> 
> Yes, we have a system with AC and DC coupled arrays on an off-grid system. Having DC coupled capacity is important for reasons given in other posts.
> 
> We used AC coupling due to shade issues, so we could use Enphase inverters.
> 
> In your case, if the house really is going to go on grid, I would think AC coupling makes sense. If not, I'd use high voltage DC charge controllers (like the Schneider 600 V units) and keep it DC.
> 
> The main complaint I have with AC coupling off grid is that some lights tent to strobe in certain charging conditions. Another complaint  is the 5 minute delay period after the micro-inverters shut down. The micros are phased, based on battery voltage, so they don't all shut down at once.
> 
> 
> 
> Drake Chamberlin
> 
> Athens Electric LLC
> 
> Ohio Electrical Contractor’s License 44810
> 
> CO Master Electrician’s License 4526
> 
> NABCEP Certified PV Installation Professional
> 
> 
> 
> 
> 
> ---
>  
> 
> 
>> On 2022-07-30 12:30, Kirk Herander via RE-wrenches wrote:
>> 
>> All,
>> Anyone out there successfully AC-coupled inverters in an off-grid system? Advantages vs. pitfalls?
>>  
>> In my case I'm thinking of its practicality with a Solaredge inverter AC-coupled to an OB Radian inverter. OB firmware makes this pretty easy now. So effectively the Radian is always operating in a grid-backup mode.
>>  
>> I already upgraded the system to the Radian, and soon to add 5kw of pole-mounted PV(currently only 1.8kw of 22-year old PV on the roof). This system also just got 16kwh of Blue Ion LFP batteries.
>>  
>> This is a last-minute thought I have instead of investing in additional DC charge controllers for the new array.
>> Cost-wise there's not much of a difference between several high-quality charge controllers and a smaller SE inverter w/optimisers. Thanks.
>>  
>> -- 
>> Kirk Herander / kirkh at vermont.solar
>> Owner|Principal, VT Solar, LLC
>> Celebrating our 31st Anniversary 1991-2022!!
>> www.vermont.solar
>> dba Vermont Solar Engineering
>> 802.863.1202
>> 
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