Does anyone know full charge kWh amount?

[Azrich]

In a couple weeks I'm having a roof solar panel company come to my home to discuss the possibility of putting panels on part of my roof of my house. (Company: Technicians for Sustainability) My roof is not huge but I want to at least get enough panels to recharge my LEAF. Does anyone know the amount of kWh needed for a full charge? Even though I won't need a full charge every night, this would give me a starting point.

Later I will ask more questions about solar panels because I know many of you are already generating electricity with them.

Thanks.

 

[sjfotos]

Hi Azrich,
I am seeking a similar answer. I have Astrum Solar visitng to assess my situation as well. One thing I liked about their design was the use of a micro-inverter for each panel. That way you can monitor the performance of each panel as an individual unit. I'll post some more info as i get it and appreciate your post as well!
Steev

 

[mitch672]

If you emptied the pack every day, it would need 24Kw/day, but you probably won't, and also your house has other electrical needs as well.

FYI, of major importantance for solar is WHERE you live, and how may hours/day of peak daylight you have (refered to as 'solar insolation'), in the western US (California, Nevada, Arizona, etc), there are many more hours of usable, cloud free daylight than we have here out on the eastern seaboard Here is a solar insolation calculator, it can help you analyze your area for solar, this is what most professional solar installers start with

http://www.pvwatts.org/

and, yes sjfotos, the enphase micro inverters are great, because if you have a few trees, you only lose output power on 1 panel, versus the entire string.

enphases technology:
http://www.enphaseenergy.com/products/ourtechnology.cfm

how it works:
http://www.enphaseenergy.com/products/moreinfo/howitworks.cfm

enlighten, monitor your system on the web, sample installations
http://enlighten.enphaseenergy.com/systemslist

Do it yourself? maybe, but you will need help and an electrician for the permiting
http://store.solar-electric.com/enmigrsy.html

Yes, I have been investigating this for a while now

 

[Azrich]

mitch, I'm in Tucson - lots of sun. There are no trees shading roof. Should I still consider using enphase micro inverters?

Pardon my lack of any knowledge about this topic, but you said the battery pack would need 24 Kw/day for a full charge. Can you convert that to kWh or is it the same?

 

[evnow]

Does anyone know the amount of kWh needed for a full charge? Even though I won't need a full charge every night, this would give me a starting point.

The battery is 24kwh - if we assume a 80% max useable, that would be about 20 kwh.

 

[mitch672]

azrich, the enphase system doesn't have too much of a premium these days over a "traditional" string inverter, and their website/reporting is very nice. You might even be able to sell the "SRECs" (Solar Renewable Energy Credits) with the reporting that their "enlighten" system provides. SRECs are sold at auction, but could be worth $300-$600 per MwH, this helps with your PV payback.. around here the value of the SREcs is about twice the value of the electricity produced, so it's like you are getting paid 3 times the price per KW, once because you generate it yourself and don't need to pay your utility, and twice on the value of the SRECs you can sell to your utility or at auction. Here is the SREC trade website: http://www.srectrade.com/ It's most eastern/central US, doesn't look like Arizona participates...

Find some PV systems in Arizona using the enphase system, this will give you an idea of what you might expect, the number of panels is listed for each site as well. BTW, I own a small property in Arizons (Meadview, near lake mead in the high desert 75 miles from Vegas), I will probably put in some solar when I build a retirement home.

http://enlighten.enphaseenergy.com/all_public_systems

 

[sjfotos]

Thank you mitch672. I will be interested to see what they suggest. They completed a survey this past week and will schedule a meeting soon.

 

[Cacti]

"The Mini E gets about 4 miles per kilowatt-hour, Peder said, which means 12,000 miles in one year will require 3,000 kWh - which, as noted before, is what the Norbys are experiencing. To generate 3,000 kWh, you'd need a 2-kilowatt photovoltaic system. Each kilowatt PV system generates about 1,600 kWh per year."

http://blogs.edmunds.com/greencaradvisor/2010/03/rooftop-solar-panels-energize-home-and-mini-e-at-low-cost-and-with-no-emissions.html

Hope this helps?

 

[mitch672]

"The Mini E gets about 4 miles per kilowatt-hour, Peder said, which means 12,000 miles in one year will require 3,000 kWh - which, as noted before, is what the Norbys are experiencing. To generate 3,000 kWh, you'd need a 2-kilowatt photovoltaic system. Each kilowatt PV system generates about 1,600 kWh per year."

http://blogs.edmunds.com/greencaradvisor/2010/03/rooftop-solar-panels-energize-home-and-mini-e-at-low-cost-and-with-no-emissions.html

Hope this helps?

It really depends on where you are in the country and what the "solar insolation" in your area is, that's why I posted the link to PV Watts...

 

[garygid]

A typical family house might use 10 kWh to 20 kWh per day (300 to 600 kWh per month) when not air conditioning, and perhaps 1200 to 1500 kWh per month (40 to 50 kWh per day) when using the air conditioning. These are just some figures to use for discussion here.

Check your own monthly electricity bills for your own "kWh" usage for each of the last year's usage, and add them to get your full years usage.

Then, plan extra for additional uses (adding electric water heating, or air conditioning, etc.).

Perhaps subtract for energy efficiencies (new refrigerator, dual-pane windows, etc.).

Adjust for future usage changes (like retirement and staying home more, and needing to use the air conditioning more during the day, or just being more comfortable).

Add big new uses, like an EV. Including conversion and generation losses, a single "full" Leaf charge might take 25 kWh (19 kWh usable into the battery). Factor in expected usage to get an average kWh per month value.

Decide how many kWh (if any) you are willing to buy from your utility company (or how much you want to over-produce).

Get an estimate on that size PV system, recover from the "sticker shock", readjust the steps above to get to your "affordable" range, and try again.

Lastly, see if your situation can accomodate the physical size and "facing" needed for your desired PV system, and adjust again.

 

[Azrich]

Cacti, I'm assuming that is you and your Mini's in the article. That is a great article and gave me a lot of information. I just wish my garage was in such good order!

garygid, thanks for the step by step process on how to figure all this. Our home is only 1700 square feet and has a flat roof. One problem is that there are 7 skylights to work around. I think our best flat space is above the garage and one bedroom.

I've asked about ten people in Tucson who to go to first about the installation and 8 people said a group called Technicians for Sustainability. They have done many home but also some large businesses like Canyon Ranch Resort, just over the hill from me.

I want to ask them about the panels that move and follow the sun too. Any thoughts?

 

[garygid]

On a flat roof, you will probably want tilted panels, either a fixed (average) tilt, or possibly a somewhat more expensive varible-tilt, even a manual crank that you might change 6 times a year.

If the roof access is easy, then even 3 "hooks" on the upper rail for a winter top position, spring and fall middle position, and a lower summer position might be easy to do.

However, sufficiently sturdy mounts for real sun-following is probably substantially more expensive (need to consider highest-speed winds).

 

[sjfotos]

LA Times Article on one person's experience.


http://www.latimes.com/news/custom/topofthetimes/features/la-hm-realistidealist-20100508,0,4646090.story

 

[JasonT]

I've asked about ten people in Tucson who to go to first about the installation and 8 people said a group called Technicians for Sustainability. They have done many home but also some large businesses like Canyon Ranch Resort, just over the hill from me.

I want to ask them about the panels that move and follow the sun too. Any thoughts?

I also went with Technicians for Sustainability. We had some slight scheduling issues (they would just show up expecting access to the house - luckliy I work from home so it ended up not being an issue), but other than that they were great. I went back to them when I expanded my system - I've now got a 5.25kW system running.

I haven't done a lot of research on it, but from what I understand the added expense, maintainence, and power needed for motorized panels just isn't worth it. I've heard stories of people ripping out/disabling their moving panels and just going with fixed.

 

[Jimmydreams]

I haven't done a lot of research on it, but from what I understand the added expense, maintainence, and power needed for motorized panels just isn't worth it. I've heard stories of people ripping out/disabling their moving panels and just going with fixed.

I think a lot of that depends on what type of moving platform you're using. I've seen solar-tracker arrays of 9-12 panels mounted on an old satellite antenna pole. I haven't read much about those being nightmares when it comes to maintenance, but they DO put out about 30% more wattage than a fixed array. THAT'S something to consider over the long-term.

 

[evnow]

Anyone trying to findout how much PV you need try this out.

http://www.findsolar.com/Widgets/CalculatorEmbed.aspx?t=utility&id=291

This will calculate PV needed, cost etc using the insolation based on your zip code.

 

[AndyH]

If you emptied the pack every day, it would need 24Kw/day, but you probably won't, and also your house has other electrical needs as well.

The battery is 24kwh - if we assume a 80% max useable, that would be about 20 kwh.

I think Mitch has it. The folks from Nissan (as reported during the NY stop of the cross-country trip) said the user would have access to 80% capacity - from 90% SOC to 10% SOC. They also said the user would have 24kWh available.

The pack has 48 modules of 4 cells. Each cell holds 33Ah. 100% full on LiMN is 4.2V per cell. Total capacity if charged to 100% is 26.6kWh.

[This number is above 24 so I think we're safe to call the 24kWh number the 'consumer capacity'. I suspect that the 33Ah capacity reported by AESC might be reduced as well. The cells could be closer to 40Ah each. If that's the case, a full pack would hold 32,256kWh and 80% of that is 25.8kWh]

Andy

 

[Cacti]

azrich,

"Cacti, I'm assuming that is you and your Mini's in the article. That is a great article and gave me a lot of information. I just wish my garage was in such good order!"

Unfortunately that was not me in the article, although I do have a 5.28 kW array but I do not have a garage.

Cacti

 

[evnow]

I think Mitch has it. The folks from Nissan (as reported during the NY stop of the cross-country trip) said the user would have access to 80% capacity - from 90% SOC to 10% SOC. They also said the user would have 24kWh available.

The pack has 48 modules of 4 cells. Each cell holds 33Ah. 100% full on LiMN is 4.2V per cell. Total capacity if charged to 100% is 26.6kWh.

[This number is above 24 so I think we're safe to call the 24kWh number the 'consumer capacity'. I suspect that the 33Ah capacity reported by AESC might be reduced as well. The cells could be closer to 40Ah each. If that's the case, a full pack would hold 32,256kWh and 80% of that is 25.8kWh]

Hmmmm .... I had not heard of this before. If this is the case, then they are even cheaper than $375/kwh.

26.6 * 90% = 23.94. So, may be the max available is 24kwh, out of which 21.28 kwh will be used (i.e. 10% remaining of original 26.6). I'd read/heard about the 21.3 (or 21.6 ?) kwh of usable capacity - this would indicate that.

If the pack is even bigger and 24 kwh is indeed usable, then I thing the real world range will be close to 100 miles and low speed driving will give better range.

 

[mitch672]

Here is the link to the modules: http://www.eco-aesc.com/en/bmodule.html
seems to indicate nominal voltage of 14.4 volts per module (made up of 4 cells),
assuming 24 modules per string, that is 345.6 volts nominal at 33AH, or 11404.8 watts.
multiply that by 2 (for 2 strings of 24 modules), and we get 22809.6 watts, or 22.8kw

Of course we don't have any real detailed specs on the modules, just a few lines on this webpage.

on this page http://www.eco-aesc.com/en/bpack.html they show the strings made up of 6 modules, so who knows...

EV Module
Weight:3.5kg
Nominal Voltage:14.4V
Capacity:33Ah
Size:315×225×36