net-metered efficiency observations [RE-wrenches]

[Kirk Herander]

I have a net-metered system: 4 kw of pv on Zomeworks trackers, regulated
by -2- Outback MX-60's. The sell voltage is set to 52 volts, and the mx-60's
are in MPPT bulk charge all day, except for occassional auto-recal. Using
the form 12s meter to measure PV power converted to AC in a 48 vdc battery
based Xantrex SW system, I observed the following. On a recent sunny day,
the AC kilowatt-hr meter registered 20 kwh. The total DC kwh registered on
the mx 60's was 23.8 kwh for the day. So this gives an dc/ac conversion
efficiency of about 84%. Although this might be a somewhat simplistic means
of measuring conversion efficiency, is 84% reasonable for a battery-based
system w/MPPT controllers? I might of thought it to be a little less than
this......



Vermont Solar Engineering
Kirk Herander
North American Board of Certified Energy Practitioners
Certified Solar PV Installer(TM)
Xantrex Certified Dealer Charter Member
NYSERDA-eligible installer
Vermont Solar and Wind Partner

PO Box 697
Burlington, VT. 05402
www.vermontsolar.com
www.backeastsolar.com
800.286.1252 - 802.863.1202
fax 802.863.7908

- - - -
To send a message: RE-wrenches at topica.com

Archive of previous messages: http://www.topica.com/lists/RE-wrenches/

List rules & etiquette: http://www.mrsharkey.com/wrenches/etiquete.htm

Check out participant bios: www.mrsharkey.com/wrenches/index.html

Hosted by Home Power magazine

Moderator: michael.welch at homepower.com
--^----------------------------------------------------------------
This email was sent to: michael.welch at homepower.com

EASY UNSUBSCRIBE click here: http://topica.com/u/?bz8Qcs.bz9JC9.bWljaGFl
Or send an email to: RE-wrenches-unsubscribe at topica.com

For Topica's complete suite of email marketing solutions visit:
http://www.topica.com/?p=TEXFOOTER
--^----------------------------------------------------------------