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Plan: Off grid solar with a Model S battery pack at the heart
- Thread starter wk057
- Start date
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- Energy Environment Policy
Still reading. Have you measured degradation on your storage batteries? Or total kWh through them?
Sorry about the thread revival! I wanted to check up and see how this has fared over time. I have been using 5 modules in my RV system for about a year now with no problems whatsoever. I built it last summer. It does not get the daily usage that wk057's system gets though. I am planning a 12 module build for an off grid solar telecommunications site and wanted to hear thoughts on going with Tesla Modules. Now that your system is around 5 years old, I was just curious about how it's holding up? Looking for any input on how much capacity the batteries have left. Any issues with balancing etc?
Beautiful system by the way!
Here's a few pics of my RV setup. We love it!
Beautiful system by the way!
Here's a few pics of my RV setup. We love it!
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When I first built this I was only using the trailer. I hadn't planned on drilling holes in the RV roof. 3 of the trailer panels are in series and the other 2 are in series as well. I couldn't fit 6 panels otherwise that would have worked with just one controller. All 5 in series was too much voltage for the controller. I could have used different panels however I already had the panels and extra controllers from a different project.
For the RV roof, the panels are different size, specs etc compared to the trailer so they had to be separate. If memory serves me right it was too much amperage to use 1 controller for the roof panels. I am running my system at 24 volts as I already had the Inverters, DC-DC power supplies (To make 12v for RV lights, jacks, slides etc). I'm sure a 48v system would have allowed less controllers.
-Jason
Yaaaah...I wondered if something like that might have been the situation. It really is frustrating trying to coordinate different sets of panels coming in at different times and with different wattages and so forth. I have now three controllers that are not just different sizes, but different brands as well.
SeminoleFSU
Voluntaryist
DAMN. That's super sweet. Wish I had the know-how to put something like this together!!
4825 Total wattage RV and trailer. They are all permanently flat mounted though so in the wintertime they only run about 50-55 percent of capacity. It's plenty of power for wintertime though. I wanted it to be nearly invisible and not have to worry about climbing up, tilting etc.
SeminoleFSU
Voluntaryist
Very cool. You said you did it all yourself? How many man hours would you estimate you have in it?
I’m doing something similar with a model 3 battery. Did you figure out how to communicate with the battery pack?EDIT/Update:
Near real time stats for my setup at wk057.solar.
EDIT/Update:
Since I started this thread this project has undergone many changes and updates and has turned into something larger than originally described. Most of that info is in later posts in this thread, and I'll try to consolidate some of it here later on.
My project has been featured on Bloomberg Business, Hack-A-Day (2), and quite a few other places around the interweb. So, I'll definitely work on getting a summary setup soon.
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Some specs from later on in the thread:
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Update 2015-05-15: Roof portion of my system is completed.
Solar Install - 15.7kW Roof System - Final Compilation (Time lapse, drone shots, photos) - YouTube
Solar Install - 28.7kW Ground System (Residential) - Part 2 - Final - YouTube
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So, I have this crazy idea about using an 85kWh Model S battery pack (from a salvage Model S) as the heart of a custom off-grid solar power setup somewhere around 25kW DC.
I assume others have thought about this...
I considered making a setup where the solar panels would be setup in a configuration to produce something like 450VDC+, then making a buck converter for high efficiency charging directly from the panels. The most I've seen the battery voltage was about 404V during a 100% charge at a supercharger, so, this should be possible. Little bit of microcontroller brains to keep things sane and all should be well.
Inverter should be simple, since HV inverters already exist. Might need to step the voltage down a hair since a lot do not operate at >400VDC input. But, that's not the hardest part of this project by a long shot.
That aside, does anyone have any information about the pack itself? I'm working on physically getting one to tinker with, which will help, but I'd be curious if anyone else has done any of this already and we could save each other some leg work.
I'm also wondering if Tesla would sell any of the parts needed to interface with it, such as the high voltage connectors. I might need to just get a full salvage Model S to do this (would be cool, because then I might end up with 170kWh of battery...). Things like hooking to the coolant loop and adding a radiator and things should be trivial. Accessing the existing BMS might be hard, though, but might not be needed. Since the pack will be stationary I'll probably pop the cover off and go from there.
Even if the pack+interface items cost say, $40k, thats only $470/kWh. I refuse to go lead acid again for an off-grid setup (my previous much more modest setup used lead acid, and it was just a pain...). But for lithium ion packs of comparable size, you're looking at a price of at least that, plus a lot of labor to build the pack itself. I came up with a cost of around $500-600/kWh using off the shelf DIY EV lithium ion batteries, not counting any assembly or wiring.
Anyway, my background includes a bunch of experience with solar and related items, as well as some electrical engineering, circuit design, programming, etc. So, this is a doable project assuming I can get the materials.
Just looking for input.
(Not sure if this is the right sub-forum, but it seems appropriate)
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Just to note, part of the load of this system will be charging my Model S. I'd love to get it 100% off grid.
SeminoleFSU
Voluntaryist
@Lukej if you have a whole/intact Model 3 pack, I would suggest contacting EVTV Motor Verks - Custom Electric Car Conversion Instructional Videos and looking at some of their setups that use intact packs as a whole/complete battery.
Ir is great seeing this thread again. When wk057 started it in 2014 I was skeptical. By early 2015 I had bought a Radian and was doing a small scale version just to enhance load shifting. I am now on my third home with a strategy to self consume as much of my solar and charge my two Teslas. I have to thank @wk057 for the inspiration.
