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 <[email protected]>
To: Keith Cronin <[email protected]>; RE-wrenches
<[email protected]>
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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