| Tesla Powerwall 2 | Panasonic LJ-SK56A | |
| Initial Usable Capacity (kWh) | 13.5 | 5.3 |
| Max. Inverter Efficiency | 90% | 93% |
| Output (kW; Peak/Cont.) | 7 / 5 | ? / 2 |
| Warranty | 10 yrs; Unlimited cycles* | 10 yrs. @ 1 cycle per day |
| Guaranteed Energy Retention | 70% after 10 years | 60% after 10 years |
| Power Back-up Option? | Yes | Yes |
| Scalable? | Yes, up to 10 units | No |
| Dimensions (mm) | 1150mm x 755mm x 155mm | 1380mm x 966mm x 224mm |
| Weight | 120kg | 136kg |
| Operating Temperature Range | -20°C - 50°C | 0°C - 40°C |
| Price (including install)** | TBA | ~AUD$9000 |
How do the powerwalls work, do they have the power electronics built in to do what I described?
If you are on net metering, than why would this make sense? My parents (who live in a different country) are on net metering, so ever year, they read the consumption and production, they pay (or get back) the difference, and the pre-payment next year is based on that. Every year.
How does this work in Australia?
So, a Tesla Powerwall provides 40 MWh of storage over it's full life, approximately. It will cost you, ~15k, including solar, that is ~35 to 40 cents per KWh? Quickly at the back of the napkin.
Maybe even worse, on cloudy days it might not get a full charge.
Looking at this it is very expensive energy.
And, for the backup power function you'd need a mains breaker, correct?
If you have net metering, and it is 90 days, than I dont think it makes economically sense to install batteries. You basically just produce the energy during the day, and use it at night. Yes, in the summer (winter???) you generate more, but you would need to store that for more than 90 days. The network is the battery.'
Then it is not net metering. In net metering, first they calculate the difference between the production and consumption for the period, and you only get payed for the excess production (usually with reduced feed in tariffs), or pay for the excess consumption (normal price).
I'm sorry, but you are using the term "net metering" wrong. Maybe even the DSO uses it wrong. In net metering, if you export 10 KWh during the day, and buy back 10KWh during the night, you pay 0.
You said net metering. If you pay for selling 10KWH and buying it back, then you dont have net metering. its called Power Purchase Agreements. https://en.wikipedia.org/wiki/Net_metering#Comparison (https://en.wikipedia.org/wiki/Net_metering#Comparison) Please read this, and understand it. You are just using the term "net metering" wrong. What you have is not net metering.
There is:You said net metering. If you pay for selling 10KWH and buying it back, then you dont have net metering. its called Power Purchase Agreements. https://en.wikipedia.org/wiki/Net_metering#Comparison (https://en.wikipedia.org/wiki/Net_metering#Comparison) Please read this, and understand it. You are just using the term "net metering" wrong. What you have is not net metering.
:palm:
I'm not going to go back and forth with this. What I have in place is net metering, this is what it's known as in the industry and it's pretty universal. Rather than relying on Wikipedia, you can refer to any number of government and industry websites. The only other option is gross metering (which I don't have). You can go ahead and call it "silly sausage PV scheme" if you like, it doesn't change what it is. Anyway, moving on... this was not the point of this thread.
Net metering has one, bidirectional meter, with one number on it, which can be negative. You have two meters. Its not net metering.
Any reason why you're not building your own powerwall?
Just a simple question. If you have one meter, you produce 10 KWh during the day turns in one direction, and use it at night, turns in the other direction, it will show 0 the next day, right? So you would pay 0. But you claim, that you have a more elaborate payment scheme. I guess you have more than 1 meters then? Maybe it is not even called net metering.Net metering has one, bidirectional meter, with one number on it, which can be negative. You have two meters. Its not net metering.
For what it's worth I have a single meter, then again, I haven't checked it in about a month, a second one could have mysteriously appeared? Who knows?
Just a simple question. If you have one meter, you produce 10 KWh during the day turns in one direction, and use it at night, turns in the other direction, it will show 0 the next day, right? So you would pay 0. But you claim, that you have a more elaborate payment scheme. I guess you have more than 1 meters then? Maybe it is not even called net metering.
Based on the original Powerwall 1 (which had approximately half the capacity), the system would pay for itself within the 10 year warranty period. This was based on a 4KW PV system + Powerwall available in January 2016 for under AUD$15,000 and the average solar generation in Sydney AU on a 4KW system is about 15.6kWh per day (averaged across an entire year). Most parts of Australia have higher generation (the highest being Alice Springs at about 20kWh per day).You'll need to show your working for that, it doesnt sound like it could profit alone. Even with the poor tariff structure you have at the moment:
The 50%/50% split is a reasonable assumption for the storage, so you'd need to have a 10 year system cost less than 1.76*356*10 = $6400I'm sorry, but you are using the term "net metering" wrong. Maybe even the DSO uses it wrong. In net metering, if you export 10 KWh during the day, and buy back 10KWh during the night, you pay 0.I don't think so. Here's some maths using my current rates:
Export 10 kWh = 67c credit
Import 10 kWh = $2.40 charge
Import - Export = $1.76 out of pocket.
As you said earlier, you have to take into account the lower feed-in tariff. In this example, the proceeds from my export don't equal or outweigh my total outlay. This is by definition what the word "net" means.
Any reason why you're not building your own powerwall?
This field of electronics isn't my area of expertise. Plus I'm not licenced to touch/work on anything at 240v.
I'm sorry, but you are using the term "net metering" wrong. Maybe even the DSO uses it wrong. In net metering, if you export 10 KWh during the day, and buy back 10KWh during the night, you pay 0.
I don't think so. Here's some maths using my current rates:
Export 10 kWh = 67c credit
Import 10 kWh = $2.40 charge
Import - Export = $1.76 out of pocket.
As you said earlier, you have to take into account the lower feed-in tariff. In this example, the proceeds from my export don't equal or outweigh my total outlay. This is by definition what the word "net" means.
Any reason why you're not building your own powerwall?
This field of electronics isn't my area of expertise. Plus I'm not licenced to touch/work on anything at 240v.
Upgrading to an inverter that supports a battery (hybrid compared to grid tied or purely off grid)and making your own lithium battery from used cells mite be another option if you have the time.
Extra low voltage under 120volt DC doesn't require a licence to work on.
Here is a 24 volt string of C&D brand 1212 Amp Hour at 8 hour rate on a friend’s off grid system. I did all of the major wiring to the inverter and Pelton wheel. The Pelton wheel is connected to a brushless automotive style alternator that outputs 17 amps at 27 volts 24-7.
A big resistor dumps the excess as heat to keep the powerhouse dry. The battery room is separated from the powerhouse with a fire wall. A 3500 watt inverter supplies all the AC power.
Just to clarify one very obvious difference in how two people are using the term "net metering".Yes, exactly. The one I'm describing, the net metering is for extended time. When it is instantaneous, it is always "Power Purchase Agreement". I looked up "gross metering" since it is an unknown term, and only Australian websites come up? Anyway, I'm going to accept that it means something else on the other side of the planet, and I cannot force a country to say potato instead of potato.
One is using it on a "point in time" basis and the other is using it in reference to an extended period. Interestingly, both of these usages refer to a value determined by the net flow of electricity - it's just the time scales that differ ... and that difference is significant when it comes to the electricity bill.
Has anyone tried running a washing machine or central A/C system off an inverter? If I wanted to put my whole house on battery I imagine those two loads would be the most challenging to power because of the startup draw.
When the vast majority of your energy is bought at $0.35+/kWh, batteries may help. Given a sufficient sized array. In the end, all batteries do is allow a time shift between generation and consumption.
There is also the possibility of building a cabin where electricity simply isn't available. A real off-grid application.
Don't see the profit yet! You already said better tariffs are available to make it less attractive. Also the Panasonic quote at half the storage size is already costing more than this. You'll be betting on electricity prices (and the grids energy arbitrage ratio) increasing more rapidly than other investments. With all the blustering from the government about the energy sector I wouldn't be investing on such assumptions.I dont think it actually makes sense to be an early adapter for this kind of system, if you loose money (degradation of battery) with each charge. If electricity prices go up, you can install a battery system later. Prices are likely to drop, and reliability and number of charges are likely to go up in a future system. Imagine, they finally start mass producing aluminium-ion batteries, and prices are halved.