smkettner
Posts: 7138
Joined: Mon Aug 09, 2010 10:13 pm
Delivery Date: 26 Feb 2014
Location: Orange County, CA

Re: Solar capacity needed for my Leaf?

Thu Sep 19, 2013 10:42 am

Is it a separate meter reading gross production or reading net of usage?
1 bar lost at 21,451 miles, 16 months.
2 bar lost at 35,339 miles, 25 months.
LEAF traded at 45,400 miles for a RAV4-EV

DarthPuppy
Posts: 628
Joined: Sun Aug 11, 2013 8:45 pm
Delivery Date: 11 Aug 2013

Re: Solar capacity needed for my Leaf?

Thu Sep 19, 2013 10:51 am

smkettner wrote:Is it a separate meter reading gross production or reading net of usage?


The meter provides two readings. One reading is power drawn from SCE. The other reading is power provided to SCE. I then net the two readings to determine my surplus production.
'13 Leaf SL
'18 Honda Clarity Touring PHEV

QueenBee
Posts: 1564
Joined: Sun Aug 08, 2010 5:14 pm
Delivery Date: 20 Jun 2011
Leaf Number: 2062
Location: Bellevue (Seattle), WA

Re: Solar capacity needed for my Leaf?

Thu Sep 19, 2013 11:08 am

DarthPuppy wrote:Ok, I checked the SCE meter and it appears that over the past year, my 5.8kW (DC) system produced 7400 kWh AC, which exceeded what was used by the house by a little over 1,400 kWh.
smkettner wrote:Is it a separate meter reading gross production or reading net of usage?


The meter provides two readings. One reading is power drawn from SCE. The other reading is power provided to SCE. I then net the two readings to determine my surplus production.


Wait, doesn't that mean something else?

If you have one meter that is measuring power sent to the grid and power taken from the grid then you don't actually know how much power your system produced or how much power you produced? The only thing you know is how much more/less power you put into the grid than what you took from the grid.

But your 7,400 kwh vs 5.8kw system ratio seems to indicate that would be its total production? So maybe you have a third meter that is showing total production as well?

DarthPuppy
Posts: 628
Joined: Sun Aug 11, 2013 8:45 pm
Delivery Date: 11 Aug 2013

Re: Solar capacity needed for my Leaf?

Thu Sep 19, 2013 11:21 am

QueenBee wrote:
DarthPuppy wrote:If you have one meter that is measuring power sent to the grid and power taken from the grid then you don't actually know how much power your system produced or how much power you produced?


Good point. The missing element would be the power produced and used by the house before feeding excess back to SCE. This would suggest that my production is significantly better than 7,400 kWh over the course of a year. So perhaps a 10 panel system would be overkill.

I now have a little more thinking to do.
'13 Leaf SL
'18 Honda Clarity Touring PHEV

User avatar
Boomer23
Posts: 3540
Joined: Sun May 23, 2010 9:57 pm
Delivery Date: 30 Mar 2011
Location: Orange County, CA

Re: Solar capacity needed for my Leaf?

Thu Sep 19, 2013 11:47 am

DarthPuppy wrote:
QueenBee wrote:
DarthPuppy wrote:If you have one meter that is measuring power sent to the grid and power taken from the grid then you don't actually know how much power your system produced or how much power you produced?


Good point. The missing element would be the power produced and used by the house before feeding excess back to SCE. This would suggest that my production is significantly better than 7,400 kWh over the course of a year. So perhaps a 10 panel system would be overkill.

I now have a little more thinking to do.


Right. As I mentioned, my 5.16 kW DC system in your same geographic region generates about 8,500 kWh AC per year. If you have south facing siting with little to no shading, you should be generating about 9,500 kWh AC per year.

Last calendar year, I used 3,129 kWh AC to charge my LEAF at home to drive 11,149 miles (184 kWh of public charging also contributed to this mileage.) That translates to about 1.9 kW DC from my solar array, which is the output of about nine of my 215 W panels.
2014 BMW i3 with Range Extender
2017 Chevy Bolt EV Premier Kinetic Blue
Blog: http://drivingelectric.blogspot.com" onclick="window.open(this.href);return false;

GRA
Posts: 8656
Joined: Mon Sep 19, 2011 1:49 pm
Location: East side of San Francisco Bay

Re: Solar capacity needed for my Leaf?

Thu Sep 19, 2013 3:09 pm

DarthPuppy wrote:
RegGuheert wrote: would equate to about 3000Wp PV panels (grid-tied).


So 3,000 W is the spec I need to tell the installer that I want to add to my system? Or am I mis-translating? What is a "Wp"?

Thanks!!!

Maybe it was answered somewhere but I didn't see it: "Wp" is Watts Peak, i.e. under (rated) peak power conditions.
Guy [I have lots of experience designing/selling off-grid AE systems, some using EVs but don't own one. Local trips are by foot, bike and/or rapid transit].

The 'best' is the enemy of 'good enough'. Copper shot, not Silver bullets.

Burr
Posts: 33
Joined: Mon Sep 09, 2013 9:35 am
Delivery Date: 07 Dec 2013
Leaf Number: 400968

Re: Solar capacity needed for my Leaf?

Thu Sep 19, 2013 5:49 pm

Darthpuppy- :) We are in the same boat. I'am not far from you and I'am stuck with SCE also. I 'guess-estimated' about 2-3 kW of panels for the Leaf. Since the install is so routine,(DIY) and micro-inverters are plug-in-play, I decided to put in 2 kW of additional panels to start with. I'm using (8) 255 watt Canadian panels on about 28" of railing, with (8) 225 Enphase micro inverters . To check my work and keep the building inspector happy, I paid a good electrician an additional $150. From Craig's List, I got the Solar Panels for $206 plus tax. The Microinverters were on sale for $119 each, also on Craig's List. The railing and hardware (Prosolar) cost about $90 (yep, from Craig's list also). The additional wiring, conduit, & disconnect box came from Home Depot for about $70. Because of Work and other obligations, I took two Saturdays or 10 hours to install. Early mornings are best, to avoid the heat. About April or May next year, I'll reassess and/or add an additional (4) panels w/micro inverters. That will give me a second shot at the Federal 30% rebate. As you see I'am not an engineer either . I also don't do well at heights. Solar equipement is alot cheaper than seven years ago. DIY is a real option.......Good Luck

DarthPuppy
Posts: 628
Joined: Sun Aug 11, 2013 8:45 pm
Delivery Date: 11 Aug 2013

Re: Solar capacity needed for my Leaf?

Thu Sep 19, 2013 7:00 pm

Thanks Guy for the translation of Wp!

Boomer, your numbers are spot on versus the analysis from last year's install of the 5.8 kWh system = 9,500 kWh over the year.

I now have a proposal for 10 SolarWorld (US made) 250 panels with Enphase M215 inverters. That study is estimating a little over 3700 kWh over a year.

From what I've gleaned from these posts, that should cover at least 13,500 miles in my Leaf. Since this past month's driving suggests I'll do 14,000 miles over the year, that size should work well for me. 2 fewer panels and I likely won't have full coverage. 2 more panels and I'll likely be supplying more excess to SCE than I'm interested in.

You folks are awesome in providing insight! Thanks!!!!

Perhaps in 3 years when the MB B-Electric isn't 1st year production run, I'll add a second EV and add more solar then. I love the combination of solar power and BEV.
'13 Leaf SL
'18 Honda Clarity Touring PHEV

User avatar
RegGuheert
Posts: 6229
Joined: Mon Mar 19, 2012 4:12 am
Delivery Date: 16 Mar 2012
Leaf Number: 5926
Location: Northern VA

Re: Solar capacity needed for my Leaf?

Fri Sep 20, 2013 8:19 am

DarthPuppy wrote:I now have a proposal for 10 SolarWorld (US made) 250 panels with Enphase M215 inverters. That study is estimating a little over 3700 kWh over a year.

From what I've gleaned from these posts, that should cover at least 13,500 miles in my Leaf. Since this past month's driving suggests I'll do 14,000 miles over the year, that size should work well for me. 2 fewer panels and I likely won't have full coverage. 2 more panels and I'll likely be supplying more excess to SCE than I'm interested in.
That sounds like a nice addition to your system, assuming your roof and your wallet can handle it.

The MTBF study I did indicates that the reliability of the M215s is extremely high to date (MTBF > 1200 years) and the price on those should be very good now that the M250s are out. Since the M250s are brand new, nobody knows whether they will be able to achieve the same high level of reliability so I think the M215 is the right choice. With a 250W panel, you do not need anything bigger than the M215s (which can actually put out 225W).

Good luck with your new addition! Please give us the link to the public website for it once you get it up and running (assuming you are also installing a Envoy).
RegGuheert
2011 Leaf SL Demo vehicle
10K miles: Apr 14, 2013, 20K miles (55.7Ah): Aug 7, 2014, 30K miles (52.0Ah): Dec 30, 2015, 40K miles (49.8Ah): Feb 8, 2017, 50K miles (47.2Ah): Dec 7, 2017.
Enphase Inverter Measured MTBF: M190, M215, M250, S280

ERG4ALL
Posts: 603
Joined: Thu Sep 23, 2010 11:17 am
Delivery Date: 10 Mar 2011
Leaf Number: 000404
Location: Phoenix/Show Low AZ

Re: Solar capacity needed for my Leaf?

Fri Sep 20, 2013 9:00 am

I was told by the Enphase people that they intentionally have more panels with smaller inverters because the generation on a daily basis is a bell curve with a flat top. The total power generated is the area under the curve. The claim is that the total area is greater with more panels with a "flat top" than if you purchased fewer panels with inverters that could handle the maximum output of the panels. Just looking at rated capacity of the panels assumes that you are comparing the maximum power output of the panels without regard as to how the power ramps up and down over the course of a day. With a few more panels the power generated at ramp up comes on more quickly than fewer panels and the same with ramp down. Thus, the area on the sides of the bell curve before "flat top" is reached is greater than the amount lost at the peak.

We have Enphase inverters rather than a central inverter and they have been trouble free for over three years now. However, our array is not subjected to the extreme heat of the desert. We are at 6,700 ft. so they are relatively cool by comparison and we have less atmospheric shading. Having said that, there are a couple of good reasons to consider a centralized inverter. First is that the centralized inverter does not need to be mounted on the roof and can be cooler. This of course just depends on your climate. Second, if you ever plan on having a battery back up and going off grid, then a central inverter may be better. The reason is that when you use a battery back up, the power needs to be reverse inverted from DC back to AC. With many micro inverters this would require and additional inverter to get the power back to AC.

To further make the decision difficult, there are many reasons to go with micro-inverters and you are probably already aware of them. They do lend themselves to additional panels down the road. They function independently so if one fails the entire system doesn't fail as opposed to the central inverter. However, one caveat is that, at least in our local, the utility will not allow any more than 20% of your main electrical panel capacity to be solar. Thus, if you have 200A service to your house, then the maximum solar would 40A, thus depending on your initial installation, adding more panels later may be a moot point.

Finally, welcome to the club. We have been totally pleased with our decision.
Reserved 4/20/10, Ocean Blue Ordered SL 9/30/10, ESVE Installed 11/22/10, Delivered March 8th, 2011.

Return to “Solar”