Solar Home Battery Storage Systems

[JerryBob]

Been looking at the Solar Home Battery Storage systems on the market to get off the grid. Got a sales pitch about the Tesla Powerwall 2. Has anyone actually installed/going to install one of these in their home? Do you need 60Kwh of battery storage to charge a Bolt or is the Bolt helping power your home like on the island of Madeira, Portugal? They say it will charge an EV but I think they are still in the 22Kwh battery pack world. How long would it take to recharge the battery with in home usage at the same time. Seems like a lot of upfront cost with some infrastructure improvements to the home electrical system. Would you have to buy another system in 20 years? The brochures are very colorful and promise a happy carefree low carbon emission future.

 

[Pigwich]

The Powerwall is a neat product, but you still need power input, be it solar or grid,etc. They're infinitely better than lead acid batteries, that's for sure. Higher initial cost, but the capacity is way better, the useful life is way longer, and they don't need the maintenance. There's a ton of info online.

As for capacity, you can stack them. I wouldn't think you need 60kWh unless you plan on fully discharging your car before recharging it (plain stupid) but more battery is good if you can afford it. At my house, were EV only,and we use around 11kWh daily. You just need to be honest about your driving habits.

Charge times are dependant on what you set your charger to. If you want to pull 7 kw out of a battery system that can only supply 2.2 kw,it will trip a circuit breaker. There is nothing on the market that I'm aware of that will automatically de-rate your charger current.

Next up, reverse current flow. With the Bolt in its current implementation, the answer is NO. When we do see this, I have a feeling that it's going to come over the CCS port and the inverter will be in your garage. It's a tentative feature in the CCS 3 spec. Doing the grid integration on the car is probably more responsibility than car makers currently want. But who knows. If there was a grid inverter in the car, the current EVSEs might be able to deal with return power, but I don't think any current spec supports it.

So... No.

 

[EldRick]

At current pricing, there is no way on earth that the Tesla Powerwall would ever pay back in power savings. Reliability? Maybe, but my house draws 40kWH/day, and it would take a lot of batteries to get thru an outage.

 

[user 1485]

At current pricing, there is no way on earth that the Tesla Powerwall would ever pay back in power savings. Reliability? Maybe, but my house draws 40kWH/day, and it would take a lot of batteries to get thru an outage.

I agree. We use about 43 kWh per day, and we just endured a 36 hour outage, which would be about 60 kWh storage required to carry through that outage. We have had quite a few week long outages over the years, so clearly batteries are not there yet. Its still best to use a propane-fired generator, or a gasoline generator. However, net-metered roof solar is a good option to charge your EV. In CT, with approaching three quarters of our energy either renewable or nuclear, its a clean way to go.

 

[IMAdolt]

rgmichel, EldRick, Unless you're driving 50% of that power away you guys should really review your energy usage habits.

Anyway an expensive product like a "powerwall" really only makes sense when tied to a point of use power generation system like solar or wind or whatever you got going on. If it's simply for when the grid goes down to give you a day or so of coverage then it's a waist of money, If you must have it for that then your best bet there is to sub panel your critical systems with switchgear so you're only running like your gas furnace fridge etc. that'll stretch your battery bank quite a ways.

 

[boltage]

rgmichel, EldRick, Unless you're driving 50% of that power away you guys should really review your energy usage habits.

Also, if the high consumption is from driving EVs, a home battery may only need the capacity to be a UPS for the home, since the EVs can be driven to public charging stations to be recharged. Not as convenient as charging them at home, but lets the home battery last longer as a UPS for the home.

 

[AyeJay]

Hey JerryBob,

Next up, reverse current flow. With the Bolt in its current implementation, the answer is NO. When we do see this, I have a feeling that it's going to come over the CCS port and the inverter will be in your garage. It's a tentative feature in the CCS 3 spec. Doing the grid integration on the car is probably more responsibility than car makers currently want. But who knows. If there was a grid inverter in the car, the current EVSEs might be able to deal with return power, but I don't think any current spec supports it.

So... No.

-- I started a thread a while ago that may be of interest ..

http://www.mychevybolt.com/forum/viewtopic.php?f=12&t=7416&hilit=this+could+change+everything

AJ