Tesla Motors announces new home battery

[Great-Kazoo]

Huh... Apparently I should pay more attention to forums that I respond to... Lol.

I'll have some time to write it up early this week.

Thank you.

[Grant H.]

Alright,

Travel for work has been odd, so my schedule has been odd...

The solar solution that we did at my parents, consists of some solar panels, a sh!t load of batteries, some wire, and a few semiconductors...

Glad I could help...




I keed, I keed...

The setup is 6KW of cheap thin film panels, that were bought several years ago (stupid being busy, delaying the fun projects), when a good deal on panels was $.90/watt. We gave less than that, but we are also tied into some interesting groups through work that get some decent deals here and there. The mounts are all aluminum angle (no rust, no need to paint). My parents have a great barn roof, that faces directly south, so the mounts are pretty straightforward. We made them a little more involved so that in the next few months we can add some electro-mechanical pitch adjustment. We didn't bother with east-west tracking, despite that raising the effectiveness of PV panels drastically, because we have enough panels that they only about 12-15 hours of good sun a week, to cover their average usage. The pitch adjustment is because my parents have 3 engineers for children, and we get bored and come up with good/stupid ideas, it will be a benefit, as the optimum pitch of the panels does change a lot here, but it isn't actually necessary.

For voltage, we decided on a 48VDC system, so that losses are minimal. The only downside to the 48V choice comes in the number/cost of batteries. We use a 6VDC 215AH battery that is designed for golf carts. They have some of the best battery life we have found, and provide a fairly simple install. When we did the battery banks, we installed them in a known dry area with climate control. The better you can control the temperature of the batteries, the longer they will last. Based on their need, we used 40 batteries. 8 wired in series to provide 48VDC, and 5 sets in parallel. We don't design battery banks to allow for greater than 50% discharge. Some might call it overkill, but it protects the batteries life, which lowers maintenance cost, and speeds payback.

We used all Outback isolated charge controllers and inverters, which do cost a bit more, but the feature set, the usability, and the general install is nice with their gear.

Hopefully, this helps. I'm happy to answer questions, as I'm sure there are details that some will want that I glossed over.

[Grant H.]

For cost ideas... Since I missed that point of questions in my response...

For panels, the cost was right around $.70/watt. For 6000 watts, that means the cost was $4200ish for the panels delivered. Also, if you shop around, panels can be as low as $.50/watt now.

The batteries can be had for $100ish from BatteriesPlus. $4000 in batteries, plus tax.

2x Outback MPPT Charge controllers - $550 each

2x Outback Offgrid Inverters - $1500 each

All in all:

$10800 plus mounting and minimal ancillary wiring.

I'm going to guess ~$12-13k in the whole thing.

My parents were spending ~$100-125/month on electric, so that looks like a 10yr pay off. If things had been a little less overbuilt, the cost would be less, and the pay off would be faster. You can also get lower cost charge controllers and inverters.

Like I said, my parents have three engineers for kids, and we usually over build/over design stuff.