<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">Allan,<div><br></div><div>Can be done but I don't believe it is economical. You will have more cost in equipment yet your daily PV power production will be less. The reason is that battery charging will not use 100% of PV potential for the entire charge cycle. Every day the power will taper off as the battery gets full, the rest is wasted. This waste will add up to many kWh's. Also, the MPPT conversion efficiency will likely be less directly charging a battery compared to using a grid tie inverter. You can optimize the array voltage for one or the other but probably not both.</div><div><div>
<span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div><br class="Apple-interchange-newline">Larry Crutcher</div><div>Starlight Solar Power Systems</div></div></span></span><div>(928) 342-9103</div><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div><u><br></u></div></div></span></span></div></span><br class="Apple-interchange-newline"></div></span><br class="Apple-interchange-newline"></span><br class="Apple-interchange-newline">
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<br><div><div>On Aug 23, 2012, at 7:50 AM, Allan Sindelar wrote:</div><br class="Apple-interchange-newline">
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Wrenches,<br>
We have a customer who has built several EVs, and wants to
eventually develop a business around them here. A few years ago we
installed a GT system on his home. He has now moved and wants to
install a system on his new home as well. This time, he'd like to
develop a means by which to charge his EV directly from his array,
avoiding the inefficiencies of inverting to the grid and then
running a grid-based charger. <br>
<br>
I know of no way to do this, but then, I'm a veggiehead (drive an
old Mercedes on waste fryer oil), not an EV aficionado. I suspect
that there are folks out there trying to do this, as it's a logical
objective. Can anyone suggest products, links, or websites for this
customer to explore?<br>
<br>
Here are his notes about this effort:<br>
<blockquote>...this is essentially the idea. to use the EV as
rolling battery backup to dual-purpose the investment in battery.
The second plus is avoiding loss from two inversions dc-ac-dc, the
third being relatively high-amp charge without buying another
charger! and dual purposing the inverter to avoid cost of high-amp
inverter only used for emergencies for a backup.
<br>
<br>
The tech details of EV battery packs that are going to make this a
challenge is the high voltage. The DIY pack running DC are going
to be 120, 144, 156vDC nominal most commonly. Guys running AC
motors and OEMs might run much higher.... closer to 300v.
<br>
<br>
The charge controller or voltage limit switch needs to be user
settable and fairly accurate (+/- 1 volt). The DIY people usually
use a 'finish' voltage of 3.65volts / cell being 'done'. So for a
120v nominal system I would want to set the DC charge to come up
to 139v and either shut down right then, or if it COULD just hold
at 139v until amps drop or a specified time, that would be even
better.
<br>
<br>
I am planning to do a grid-tie system at my new house, and yes,
the intent is to 'stub-in' capability to both quick-charge the
pack direct from the DC side of PV if possible, AND use the car
pack as night-time/emergency backup just to show its possible....
<br>
<br>
My little car has 12kWhr on board, one I'm working on right now
will have 20kWhr onboard.
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Thank you in advance for any assistance.<br>
Allan<br>
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<font face="Times New Roman, Times, serif"><b>Allan Sindelar</b></font><br>
<small><a href="mailto:Allan@positiveenergysolar.com"><font color="#000099" face="Times New Roman, Times, serif"><u>Allan@positiveenergysolar.com</u></font></a></small><font face="Times New Roman, Times, serif"><br>
<span style="font-size: 10pt;">NABCEP Certified Photovoltaic
Installer<br>
NABCEP Certified Technical Sales Professional<br>
New Mexico EE98J Journeyman Electrician<br>
Founder and Chief Technology Officer<br>
<b>Positive Energy, Inc.</b><br>
3209 Richards Lane (note new address)<br>
Santa Fe, New Mexico 87507<br>
<b>505 424-1112</b><br>
<a href="http://www.positiveenergysolar.com/" target="_blank"><u>www.positiveenergysolar.com</u></a><o:p></o:p></span></font><p class="MsoNormal" style="margin-right: 722.25pt;"><span style="font-size: 10pt;"><font face="Times New Roman, Times,
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