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Tesla Energy

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Re: Tesla Energy

#471

Post by andor436 »

wiremine wrote: post #310

What I'd love to see is a ROI calculator that: * uses my zip code to figure out what my non-peak costs might be. * allows me to optionally calculate solar energy capture (so I can see what impact having solar would be, given the average sunny days in my area) * takes into account the wear and tear average cold weather would have on the lifetime of the batter and the payback period. For example, I live in Michigan, an…

I also live in Michigan, and can tell you it will be a money loser for one major reason: the full cost of the system you install will be added to your local property tax valuation, as the state tax exemption on renewable energy equipment was nullified several years ago and never replaced. In my case I had $500 in taxes added to my annual bill, which outpaces the value of the energy I produce and creates an infinite payback period.

Wait until this tax issue is resolved, then it will actually make good sense here. (It's sunnier than most people think!)

Re: Tesla Energy

#472

Post by drcross »

KhalPanda wrote: post #417

For those interested in investing and finance, I have a question. Why would this news not cause Tesla's share price to go up? It seems generally well-received (well, as much of an indicator as 812 points on HN is). Surely that's a good sign? Or did the announcement not live up to the hype, causing people to dump stock?

buy on the rumour, sell on the news.

Re: Tesla Energy

#473

Post by Hengjie »

rhino369 wrote: post #454
ZoFreX wrote: post #261

This is a three-pronged stroke of genius: 1) Immediate benefits to just about anyone. If you have your own solar panels, you need this (or something like it). Even if you don't, you can benefit by drawing more power during cheaper off-peak times. 2) If lots of people get in on this, we'll have the storage capacity we need on the grid to be more dependent on renewable energy. Lack of storage capacity is one of the big…

1) You don't need this if you have solar. Most states and utilities have pretty favorable subsidies for "selling back" energy to the grid. The utility is credit the feeding back to the grid at 100%. This device will introduce efficiency losses and it is expensive. Unless you have extreme peak v. non-peak fees, I doubt this will save you money. Even at 20 cent difference, 7kW hours is a 1.40 a day. But that assumes th…

I tend to disagree that the subsidies make sense. In New Zealand, the sell back price recently was reduced in half. The problem is that the price is effectively set by the electricity supplier, which means it's not exactly competitive to sell back. It's gotten to the point where the ROI calculations from this reduction has affected the feasibility of installing solar panels in NZ.

Re: Tesla Energy

#475

Post by drcross »

grecy wrote: post #156
localhost wrote: post #41

I'm going to install a 9kW solar grid on my roof in the next couple of months - capital cost is ~$40K USD. Without the Power Wall, I'd be selling power back to the utility at around $0.10 / kWh, and buying it back at $0.09 / kWh in the evenings. The Power Wall will also let me endure grid outages as well (you can't run your house on your solar panels directly). I'm really curious about what the end-user cost is going…

> 9kW solar grid on my roof in the next couple of months - capital cost is ~$40K USD That's crazy expensive. My parents just installed 5kW last month in Australia for $10k AUD (and the government rebated them $5k AUD) so their out-of-pocket was $5k, or $1k / kW, fully installed, including the inverter.

As someone from a country that gets less sunlight, how do you know the difference between good solar cells and less efficient ones?

Re: Tesla Energy

#476

Post by blacksmith_tb »

ZoFreX wrote: post #261

This is a three-pronged stroke of genius: 1) Immediate benefits to just about anyone. If you have your own solar panels, you need this (or something like it). Even if you don't, you can benefit by drawing more power during cheaper off-peak times. 2) If lots of people get in on this, we'll have the storage capacity we need on the grid to be more dependent on renewable energy. Lack of storage capacity is one of the big…

I am not so sure. On paper, I would be an ideal candidate, I have a 4.8kW PV system (20 panels), with an inverter the Tesla could likely use. But in practice I generate enough extra power during the sunny months to have credit for the winters, and that's in Portland OR. $3K for a whole-house UPS seems like a lot, somehow...

Re: Tesla Energy

#477

Post by tedunangst »

viewer5 wrote: post #442
dragontamer wrote: post #437

Earlier quoted context omitted.

While you are correct, you can at least snuff out a gasoline fire. Lithium fires do not require oxygen, so your typical Class ABC fire extinguishers won't actually work on it. You need a class D (dry powder) extinguisher, which is very rare and expensive.

> Lithium fires do not require oxygen I thought fire is by definition a combustion reaction, meaning some kind of material reacting with oxygen. What's fire, then? (I feel like a little kid, having to ask that...)

Generally, a fast exothermic reaction. Oxygen may be the most popular oxidant, but not the only one. Lots of stuff burns in pure chlorine gas, for instance.

Re: Tesla Energy

#478

Post by toddh »

rhino369 wrote: post #454
ZoFreX wrote: post #261

This is a three-pronged stroke of genius: 1) Immediate benefits to just about anyone. If you have your own solar panels, you need this (or something like it). Even if you don't, you can benefit by drawing more power during cheaper off-peak times. 2) If lots of people get in on this, we'll have the storage capacity we need on the grid to be more dependent on renewable energy. Lack of storage capacity is one of the big…

1) You don't need this if you have solar. Most states and utilities have pretty favorable subsidies for "selling back" energy to the grid. The utility is credit the feeding back to the grid at 100%. This device will introduce efficiency losses and it is expensive. Unless you have extreme peak v. non-peak fees, I doubt this will save you money. Even at 20 cent difference, 7kW hours is a 1.40 a day. But that assumes th…

In our area (the bay area), you can't have battery storage and have a grid connection. So in the setup you describe when the power goes out we couldn't run our house on solar energy. We would have to wait for the grid to come back up. It's crazy. That means batteries would be necessary. But we don't have a battery room or room for one. So this is the perfect solution. Will it save money? Tier 4 pricing with PG&E is 34 cents per kwh and the rates are going up. In the summer it's quite easy to hit tier 4.

Re: Tesla Energy

#479

Post by dragontamer »

warfangle wrote: post #446
dragontamer wrote: post #437

Earlier quoted context omitted.

While you are correct, you can at least snuff out a gasoline fire. Lithium fires do not require oxygen, so your typical Class ABC fire extinguishers won't actually work on it. You need a class D (dry powder) extinguisher, which is very rare and expensive.

While true for lithium fires, a venting lithium-ion battery is not a typical lithium fire. According to the MSDS for lithium ion batteries, fires involving them can be extinguished with a typical ABC fire extinguisher. Lithium batteries (not the rechargeable kind) are the ones that need a class D extinguisher. Edit: > CO extinguishers, halon or copious quantities of water or water-based foam can be used to cool down…

Using water on an electric fire sounds like a dumb idea to me. But yeah, the MSDS does seem to say that...

Re: Tesla Energy

#480

Post by mfringel »

cmelbye wrote: post #36
agumonkey wrote: post #16

2 billion battery packs, and how many solar panels to feed them ? Did I miss the number ?

A lot of the stuff Tesla is saying about this is quite weird. (In the press kit and in Musk's live stream.) For example, the first sentence of the press kit: > The world currently consumes 20 trillion kWh of energy annually. Enough energy to [...] supply energy to a nuclear power plant for 2,300 years. Am I missing something, or is that an entirely bizarre comparison to make? What does this even mean?

Not a direct reply, but to put some scale around the numbers:

20,000,000,000,000 kWh = 20,000,000,000 MWh = 20,000,000 GWh / 8,760 hours/year ~= 2,283 GW average steady-state generation, globally.

A typical utility-scale nuclear reactor produces around 0.5 GW.

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