[RE-wrenches] Off Grid Optimizers

Thu Oct 31 11:52:42 EDT 2019

I don't think adding micro inverters is too crazy idea, since you 
already have a DC coupled array in the system. I just wouldn't go too 
much power over the base load though.  Also splitting the array on East 
and West faces will help spread the production out over the day and 
avoid the clunky "on/ off" control from the frequency shift or relay 
control scheme.  I'd also set the DC controller to do the final 
charging, maybe a 1/2 to 1  v higher than the setting for the AC coupled 
array.  Basically as the batteries reach the absorption phase, the AC 
coupled array would drop first, and the DC coupled array would do the 
actual 3 stage charging.

I've been against AC coupled arrays for off grid, but I think they can 
be worked into a larger system as long as there is plenty of DC coupled 
array.  In my mind, the AC coupled array offsets daily loads, while the 
DC actually charges the batteries.  Maybe you could put some of the new 
subarray less likely to be shaded on DC, and then put the lower, more 
shaded modules on micro inverters?

Ray Walters
Remote Solar
303 505-8760

On 11/1/19 9:04 AM, drake.chamberlin at redwoodalliance.org wrote:
> After doing research, it seems that the optimizers won't do what is 
> needed for the shading and orientation issues. The modules will be on 
> the east and west pitches of the roof.
>
> There is an existing array with a Midnite Solar Classic. There are 4 
> sub-arrays of 3 modules each , all facing due south  that act 
> independently.
>
> The new sub-array has more shading and orientation issues. We may need 
> to cut more trees, but would rather not.
>
> Although it seems radical for an off grid system., I'm considering 
> using microinverters, AC coupled to a Radian. Is this idea totally crazy?
>
> Thank you,
>
> Drake
>
>
>
>     ----- Original Message -----
>     From:
>     offgridsolar at sti.net "RE-wrenches" <re-wrenches at lists.re-wrenches.org>
>
>     To:
>     <glenn.burt at glbcc.com>, "RE-wrenches"
>     <re-wrenches at lists.re-wrenches.org>
>     Cc:
>
>     Sent:
>     Wed, 30 Oct 2019 16:11:20 -0700
>     Subject:
>     Re: [RE-wrenches] Off Grid Optimizers
>
>
>     Probably for shading! I cut the trees down to avoid all shading
>     offgrid.
>
>     Dave Angelini Offgrid Solar
>     "we go where powerlines don't"
>     http://members.sti.net/offgridsolar/
>     e-mail offgridsolar at sti.net
>     text 209 813 0060
>
>     On Wed, 30 Oct 2019 19:02:58 -0400, "Glenn Burt"
>     <glenn.burt at glbcc.com>
>     wrote:
>     > Then again, why optimizers?
>     > Rapid shutdown MLPE exist without the complexity and cost of
>     optimizers,
>     so
>     > I too am perplexed.
>     >
>     > Glenn
>     >
>     > -----Original Message-----
>     > From: RE-wrenches <re-wrenches-bounces at lists.re-wrenches.org> On
>     Behalf
>     Of
>     > William Miller
>     > Sent: Wednesday, October 30, 2019 5:34 PM
>     > To: RE-wrenches <re-wrenches at lists.re-wrenches.org>
>     > Subject: Re: [RE-wrenches] Off Grid Optimizers
>     >
>     > I think I know this one: For rapid shutdown?
>     >
>     > William
>     >
>     > Miller Solar
>     > 17395 Oak Road, Atascadero, CA 93422
>     > 805-438-5600
>     > www.millersolar.com
>     > CA Lic. 773985
>     >
>     > -----Original Message-----
>     > From: RE-wrenches
>     [mailto:re-wrenches-bounces at lists.re-wrenches.org] On
>     > Behalf Of Allan Sindelar
>     > Sent: Wednesday, October 30, 2019 2:11 PM
>     > To: RE-wrenches
>     > Subject: Re: [RE-wrenches] Off Grid Optimizers
>     >
>     > Drake, I must be old school - why use optimizers?
>     > Allan
>     >
>     >
>     >> On Oct 30, 2019, at 1:00 PM, drake.chamberlin at redwoodalliance.org
>     wrote:
>     >>
>     >> Hello Wrenches,
>     >>
>     >> What is the best combination of charge controller and optimizer
>     to use
>     > with an off grid, battery based system? What combinations are
>     problematic?
>     >
>     >>
>     >> Thank you,
>     >>
>     >> Drake
>     >> Athens Electric
>     >> 740-856-9648
>     >>
>     >>
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