DIY Tesla powerwall

[sed6]

I did not think I'd ever end up here, in a solar forum showing off my stuff. But the CV-19 scare made me realize my energy dependence and I started collecting components a couple months ago.



My initial plan was something portable and it worked out well. You can see some details in my 10kWh Portable Tesla Generator thread. Alas 130+ lbs isn't very portable, so I decided to mount everything properly.



I started with my panels on the roof. 260w REC that I have wired up 2S2P for 60 volts and 17 amps. Getting those suckers up there by myself was a challenge! Eventually I used some bolts, large fender washers and wing nuts, temporarily screwed into the factory mounting holes, to hang them on the gutter while I climbed the ladder.



Juice from my panels will run to my garage, where miraculously I have a small blank wall available.



Juice will run through three breakers: PV in from the roof to two 20 amp breakers to break both positive and negative on the way to my MPP LV2424 Hybrid inverter. My battery is protected by two 70 amp breakers. A/C IN and OUT will each get their own 20 amp breaker.



Last up is my wire run. With 50' from my panels to my batteries voltage loss was a big concern. I went with 6/2 MC cable with ground. I got lucky and found it for $1.50/foot locally! 50' of 6/2 at 60 VDC and 17 A will allow for just a .67v or 1.1% drop.




My MPP LV2424 Hybrid inverter is on the way and soon I'll get my other breakers up. I'll post some updates as I go.

Questions, comments or concerns are welcome! Thanks for looking!

 

[Pacer]

I love this! I will be following along to watch this project evolve. Nicely done!

 

[JoeHam]

Great work! I love how you used the gutter to help.

What is your solar panel mounting system and rails?

 

[sed6]

I love this! I will be following along to watch this project evolve. Nicely done!

Thanks!

Great work! I love how you used the gutter to help.

What is your solar panel mounting system and rails?

Thank you. The first one I hauled up on my back with a strap! It was breezy out and I thought they're must be a safer way to do this. The rails are Unistrut from Home Depot which they call Superstrut. The mounts and flashings and stand offs I fabbed up myself.







I made some additional progress tonight in that I wired up my AC breaker.




That wall outlet goes straight to my breaker box and there is nothing else on that circuit. I'm going to take the power going into the wall outlet box, bypass the outlet itself and hook it to AC IN on my MPP for grid connection. The AC OUT on my MPP will then go into that wall outlet box and power the outlet.

I really puzzled over this hybrid inverter, and the whole concept of a critical loads panel. I don't want to mess with a new panel but I need AC out to some potential load for me to consider this a "system". So that outlet can serve any loads I decide to plug into it but otherwise the energy I produce will be fed back into my panel to serve my home. And yes the LV2424 has anti-islanding built in so no lineman will be endangered. It also has a programable schedule to set when I feed the grid (house). I plan to schedule that to match my electric companies terrible TOU rates from like 3-7 pm.

More soon, thanks for looking.

 

[sed6]

Here's some info on the MPP LV2424 Hybrid Inverter. It's not perfect, but for the price there's nothing else that comes close to its features. They also make a line of high voltage hybrid inverters for anyone running lots of panels in series.

 

[sed6]

Tonight I replaced the breakers from my panel to the inverter. The original 20 amp Square D QO series breakers are rated for DC but only up to 45VDC. I can continue to use the 70 amp QO breaker on my batteries as they are 24V.



The Nader breakers I got from Home Depot and are 20 amp 230 volt. Probably nothing wrong with pushing 60v from my panels thru the 45v QO breaker, but I'm no electrician and better safe than sorry, plus they are the same price at about $10.



I'm not a fan of DC boxes, they might look okay in my RV or solar shed but not mounted on the wall of my garage above my cool Tesla batteries (no offense to anyone). As such I had to modify the Square D box by drilling and tapping two holes to hold the DIN rail. That's it! I used 10/32x3/8" screws and a bunch of washers under the rails to bring the breaker face up to the panel face. I found a 12" rail locally at Grainger for $3.50.

More to come. Thanks for looking!

 

[sed6]

Okay, more wiring to do and still waiting on my LV2424 Hybrid but I've got the breaker boxes up.



When I stand back and look I see room for expansion; maybe another battery or inverter is in the cards for the future. First I'll need more panels.

 

[Pacer]

Looking awesome!!!

 

[JoeHam]

Great stuff!

There are spec sheets on the QO breakers that state some are good up to 125vdc but they don’t provide exact numbers so I can find which ones.

Thanks for pointing out the Nader breakers. I had no idea HD carried those.

Is this the box you modified for your din rail mount?

Square D QO 100 Amp 6-Space 12-Circuit Outdoor Main Lug Load Center with Cover QO612L100RBCP - The Home Depot

The Square D QO 100 Amp 6-Space 12-Circuit Fixed Main Lugs Outdoor Load Center is UL listed for residential, commercial and industrial power distribution. This load center is built with a rugged themoplastic

www.homedepot.com

About the price of the Midnight Solar baby box but available locally.

 

[sed6]

Great stuff!

There are spec sheets on the QO breakers that state some are good up to 125vdc but they don’t provide exact numbers so I can find which ones.

Thanks for pointing out the Nader breakers. I had no idea HD carried those.

Is this the box you modified for your din rail mount?

Square D QO 100 Amp 6-Space 12-Circuit Outdoor Main Lug Load Center with Cover QO612L100RBCP - The Home Depot

The Square D QO 100 Amp 6-Space 12-Circuit Fixed Main Lugs Outdoor Load Center is UL listed for residential, commercial and industrial power distribution. This load center is built with a rugged themoplastic

www.homedepot.com

About the price of the Midnight Solar baby box but available locally.

You bet. I did have to order the breakers and had them delivered to the store. Took about a week. Here's the box I used, $13 and it has a $10 breaker inside!

Square D QO 60 Amp 240-Volt 7.4 kW Non-Fuse AC Disconnect(QO200TRCP) QO200TRCP - The Home Depot

For more than 90 years, we've been the unchallenged leader in safety switches. Our Square D brand safety switches are preferred two to one over our closest competitor. We've continued our tradition of

www.homedepot.com

 

[Antonio Pt]

Very nice construction.
I have only one Tesla module and planning on doing something similar, on 24v

 

[sed6]

Very nice construction.
I have only one Tesla module and planning on doing something similar, on 24v

Thank you. I'm going with 24v also, just doubling the capacity with two batteries in parallel. At least I think I am, all my initial battery planning was for that cheap inverter at 24v. Now that you got me thinking, maybe the LV2424 Hybrid can do more? I'll have to go look at the specs.

Edit, nope the LV2424 is a 2.4kw & 24v inverter, I'd need the LV5048. So 24v it stays!

Edit to add, I've also started working on my mount to hang my batteries. Here's a teaser pic...

 

[sed6]

Here is the basic mounting idea for my batteries. The bracket is fixed to the wall with four simple drywall anchors. The batteries rest on the bracket and then a single screw holds the top of each firmly to the wall.

I'm going to paint the bracket some color and apply a Tesla decal to my bracket. What color should I paint the bracket and what color lettering would look good? I'm leaning toward white with red lettering. Thanks for looking!

 

[Antonio Pt]

Very nice work !! Keep it.
We are confined to "covid" so my solar project is in pause...
Thanks @sed6 for answering

 

[sed6]

More progress. Got the batteries mounted and my old MPPT and GTI hooked up temporarily until my LV2424 Hybrid arrived. It's all plugged in and feeding the house/charging my batteries!

 

[sed6]

I had some questions come up from a pic I posted in another thread.

What is in the 3rd gray box? It looks like it is connected to itself with a 3' heavy gauge wire.

That is a temporary install until my LV2424 arrives. Those wires will be cut in the middle and serve as AC in and AC out to my inverter. They are not hooked up now.

I can't see the picture well but what I can see raises questions.
Are you backfeeding through a nema 5-15p?

What's that mean? I'm backfeeding thru a 20 amp CH breaker in my main breaker box. The third box asked about above houses dual 20 amp QO breakers, one to break AC in from the grid to my inverter and one to break AC out from my inverter to the grid, once hooked up.

 

[John Frum]

What's that mean?

NEMA connector - Wikipedia

en.wikipedia.org

 

[sed6]

NEMA connector - Wikipedia

en.wikipedia.org

Thanks! So NEMA is a fancy word for power cord, then yes, temporarily via that cheap ebay GTI. My wall plug is a 5-20R though. Tell me your concern, I'm noob and need to learn.

 

[John Frum]

Thanks! So NEMA is a fancy word for power cord, then yes, temporarily via that cheap ebay GTI. My wall plug is a 5-20R though. Tell me your concern, I'm noob and need to learn.

Backfeeding from p to r means the potentially exposed pins are energized.
That is dangerous.

 

[sed6]

Backfeeding from p to r means the potentially exposed pins are energized.
That is dangerous.

What's p to r?