[RE-wrenches] Enphase 215

[Keith Cronin]

William

It seems like the product tries to be everything to all mod manu's, which is hard to do, at best.

Don't know if its a limitation in the electronics or design architecture. Could also be a strategic position to clamp down on what can be plugged into the circuit per NEC to limit their exposure to liability and keeping up with the myriad of modules hitting the market every month.

As you point out, its a delicate balance- insolation vs max harvest. Sites that are free and clear of any shading are penalized, so to speak.

I suspect they are aware of this design challenge and in the future, we will see matched inverters to the mod wattage output to not leave any watts on the table.

Within 24 months, we could even see things go a different direction- mods labeled AC rating first and DC second. If the inverter is built into the modules already, this make the language universal, like virtually all AC wiring in a home.
 

Keith


________________________________
From: William Miller <william at millersolar.com>
To: Keith Cronin <electrichi01 at yahoo.com>; RE-wrenches <re-wrenches at lists.re-wrenches.org>
Sent: Wednesday, August 24, 2011 10:49 AM
Subject: Re: [RE-wrenches] Enphase 215


Keith:

Her's my guess:  Through the MPPT algorithm.  The processor
indicates near maximum output, the MPPT impedance reduces to throttle
back power production.  

This is pure speculation, but I'm stickin' with it (untold told
otherwise).

Throwing away power?  Yes.  If MPPT is not at maximum power
transfer at all times then your investment in PV is not earning it's full
return.  However, your inverter investment is not earning it's full
return during the many hours of less than optimum insolation.  These
are the two factors to balance in system design.

William


At 01:01 PM 8/24/2011, you wrote:

David, et al
>
>Yes, their literature states max output power of 215. Not sure how that
is controlled, except for electronically. 
>
>So this could be the shunt, so to speak and must take into consideration
voltage to follow some algorithm to keep things humming along at that
threshold.
>
>Having said this- are we "throwing away" power then?
>
>Keith
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