Written Unless your Air conditioning system Refrigerant starts to Leak there is no need of Replacement or recharge. People may scam you that you need more refrigerant or Your Ac "used up" the refrigerant but don't worry about it.source: Residential & Commercial Heating and Cooling | Tesla announced a battery for your house, the Powerwall. I think this is a great opportunity to talk about batteries and physics. Let me answer some questions you might have. This is perhaps the most important question and one that has likely been addressed many times. In short, a house battery will let you be more power independent. If you have solar panels or electricity generated from wind, they don’t always produce the same amount of power. With a battery, you can store this energy during the day (or during wind) and then use it at night. A house battery will also let you get power from the electric company at night when the rates are lower and then use it during the day. You win with a lower power bill and the electric company wins with lower demand during the day.

You could always have a battery for your house. The most common way was to use lead acid batteries, like the one in your car. However, this was not so simple. You would need to have a whole bunch of the batteries and you would have to connect them together. When one battery goes out, you have to replace it. Oh, the traditional battery is also expensive and takes up lots of space.air conditioners wall units reviews The Powerwall seems to make a home battery more like an appliance. cooling capacity of ac unitIt mounts on the wall and you don’t have to maintain individual batteries, and the price seems reasonable at between $3,000 to $3,500.ac and furnace systemsYour house runs on AC current but the battery gives you DC current.

This means that you need to take the DC current and convert it to AC current. You might have a device that does this in your car so that you can plug in household items like a computer or a coffee pot. The converter takes the DC current from the car battery and turns it into an AC current so that your laptop can then take this AC current and convert it back to DC. Yes, that seems silly but it’s true. The Powerwall does not include a DC to AC converter (or AC to DC if you want to charge from the power grid). Tesla makes a 7 and 10 kilowatt-hour battery. Let’s look at the 10 kWh one—but Tesla says that you can stack these such that you could make a 20 kWh battery if that made you happy. But really, this comes down to the definition of power as the rate that you do work (or change energy). We know the energy stored in the battery and we can estimate the average power the house uses. From that, I can solve for the time to use this energy stored in the battery. What is the energy stored in a battery?

The bigger Powerwall has 10 kWh. Yes, this is a unit of energy and not power. It says that you could get a power of 10 kilowatts for 1 hour. You can convert this energy to Joules if you like – it would be 3.6 x 107 Joules (1 watt is a Joule/second). The next thing we need to calculate the run time is the power. How much power does your house use? I think 2 kilowatts is a good estimate. With that, we can calculate the time: Five hours doesn’t seem like a long time, but I bet this would get you through the night if you are using solar power (you don’t use as much energy when you are asleep). Ok, actually you would get less than 5 hours. This calculation assumes everything is 100% efficient. In fact, the battery is only 92 percent efficient and the DC to AC converter would have some energy loss as well. If you aimed for 3 hours at 2 kW, I think you would be ok. If I talk about density, you will probably think of the mass of an object divided by its volume. This would be the mass-density.

Energy density is the energy stored in a device divided by its volume. But why would you need this? Well, it tells you how large a storage device will need to be to store a certain amount of energy. What is the energy density for the Powerwall? From the Powerwall page, the battery has dimensions of 130 cm x 86 cm x 18 cm. Assuming this is a perfect rectangular cube it would have a volume of 0.201 m3. With 3.6 x 107 Joules (or 36 MJ) of stored energy, the Powerwall has an energy density of 179 MJ/m3 or 0.179 MJ/L – I don’t know why people like energy densities in Joules per liter. How does this energy density compare to other things? This Wikipedia page lists the energy density of various mediums. Looking at this data, the energy density for the Powerwall seems rather low since a lead-acid battery has a density of 0.56 MJ/L. However, maybe this is due to extra space in the Tesla battery. There is also a mass energy density (energy per unit mass). The Powerwall has a mass of 100 kg which puts the mass energy density at 0.36 MJ/kg.

This value puts the Powerwall right in the rand for Lithium-ion batteries.Homework is my favorite part. Here are some questions for you to consider.The Tesla Powerwall home battery system puts a higher-tech face on technology you can already buy: backup batteries that store the sun’s energy for use in peak evening hours, or that protect your house in a power failure. The Tesla Powerwall battery module is a small, light, maintenance-free system that is guaranteed for 10 years. It uses the same lithium-ion cells as in a Tesla vehicle. The Powerwall system runs $3,000 to $3,500 per module, and you’ll spend several thousand more for an inverter and installation.For home users, Tesla will sell two Powerwall modules optimized either for backup (power failures) or load-shifting from afternoon to evening. For business, Tesla will sell massive battery packs that can load-shift power or provide short-term UPS-like coverage until the backup diesel generator kicks in. Awesome as Tesla’s devices may be, they’re good for hours, maybe a day — not as replacement power when the grid goes down for days at a time.

Deliveries start later this year and the prices will be softened by federal tax credits of 30% of the battery price. California has a 60% be-a-fool-to-not-try-this rebate. Tesla’s quantities of scale in manufacturing will also drive the price down. Tesla is a company like Apple: It has the ability to create or legitimize nascent markets in tablets, smartphones, smartwatches (with the jury still out), and now home battery power. A basic Powerwall module is dazzlingly small at 51.2 x 33.9 x 7.1 inches (HWD) and 220 pounds. It’s small enough to be wall-mounted in your garage wall, even outside, as long as temperatures don’t go beyond -4 to +110 degrees F (-20 to +43 degrees C). The flooded batteries most commonly used today are insanely heavy, need to be checked weekly, and sit on the floor in leakproof plastic cases about the size of a thoroughbred jockey’s coffin. As I mentioned above, the Tesla Powerwall is maintenance-free and carries a 10-year warranty with an optional buy-in for a second 10 years;

it will be interesting to see if that’s a full replacement or pro-rated.Because Tesla knows how to generate media coverage, homeowners will start thinking more about battery backup. The federal and state tax credits lets homeowners line up at the government trough alongside defense contractors and transfer payment recipients (the poor, seniors). But these credits may serve a valuable purpose: To spur early adopters to invest in battery backup, which generates more battery and inverter production, which drives down prices. It’s all based on the underlying idea that the majority of Americans have concerns about climate change, and solar puts a dent in the use of fossil fuels. Elon Musk in Thursday’s press conference reiterated that climate change is a real issue.There are two Powerwall modules. There’s a 10 kWh unit optimized for backup or power-failure applications, at $3,500. There’s a 6 kWh unit for daily cycle applications for $3,000. For both, that’s before installation (definitely not a DIY project for most) and the AC-DC inverter needed to convert 350-400 volts DC power to 120 or 240 volts AC.

There may also be a charge converter needed to interface to solar panels, to manage power going into the Powerwalls if they’re not charged by energy grid power. Each runs in the low thousands of dollars.The Powerwall delivers 5 amps (at 350-400 VDC), 8.5 amps at peak. If you recall high school physics, volts times amps equals watts. For a single Powerwall, Tesla cites 2.0 kW continuous, 3.3 Kw peak. A kilowatt is 1,000 watts and a single 15-amp household AC circuit delivers about 1,800 watts and a 20-amp circuit delivers about , so you’re getting about one circuit worth of continuous power with the ability for extended periods, and the ability to draw more than 25 amps when the hair dryer or toaster oven kicks in. The Tesla Powerwall page notes that the lights in one room, or a flat-screen TV, each use 0.1 k kilowatt hour (100 watt hours), which could be one 10 watt LED bulb or TV for 10 hours a day. It rates a clothes washer at 2.3 kWh per use and a dryer at 3.3 kWh per use. In other words, a single load of wash draws down the majority of a single Powerwall unit.

Caution: These are broad calculations that leave out transformer losses, the differences between DC and AC (AC watts are calculated as volts times amps times a fudge factor of about one-third, which your physics teacher may have blown right by when he saw the class already nodding off), and a system may show less longevity when dealing with massive drains of battery power. This also assumes all 10 kWh in the specs are available for use. So take this as a start and feel free to add detailed scenarios in the comments.For longevity (power delivered over time), look to the kilowatt-hours figure: 10 kWh means 10 kilowatts delivered for an hour, 1 kilowatt for 10 hours, or 1.8 kilowatts (a 15 amp household circuit) or just under six hours. In other words, your $3,500 investment (plus inverter, plus electrician, plus solar panels) gives you one 15-amp circuit running draw for a quarter of a day. Time to think about chaining together two or three Powerwalls, and doing high-drain applications (laundry, dishwasher) early in the day on sunny days.

The average American house uses 30 kilowatt hours a day, according to the US Department of Energy. A Japanese home, smaller and more efficient, uses about a third as much power. This suggests a typical US home might need 2-3 Powerwall units. With that, you could throttle back daily demand — maybe no air conditioning and line-dry the laundry — and get a week of runtime in an extended power failure. Or you could have more than 15 amps of time-shifted power draw in the evening.People who’ve gone off the grid, or who want to take advantage of solar, shift their dryer, oven, and stovetop from electric to gas or propane. They run their dishwashers and washing machines in the morning to draw directly from the solar panels. LED bulbs are a must. A small, permanently mounted 7-10 kilowatt generator ($3,000) gets off-grid homes through multiple cloudy days and the shortest winter days.Powerwall can be joined in microgrids. For business, the upsized version is called Powerpack, and Tesla CEO Elon Musk says it’s an “infinitely scalable system.”

The basic module is a 100 kWh block at $250 per kilowatt-hour that can scale up from 500 kWh to 10 mWh. Musk could say “to infinity and beyond” if Buzz Lightyear didn’t get there first. As Musk has said, “Our goal here is to change the way the world uses energy at an extreme scale.”Powerpack has already been in low-key testing in businesses across the country including Wal-Mart. The biggest installations could be at electric generating plants, especially those with the lowest-cost or lowest-pollution electricity. They’d store energy created at off-peak hours and deliver it during late afternoon and early evening at peak demand periods. When utility officials or government planners talk about a shortage of electric generation capability, they mean “in the afternoon on a hot, humid day.” Even California has enough generating capacity from midnight to 6 a.m. Duke Energy and others are installing battery systems adjacent to wind farms and hydro power sites.The demand for the batteries in Powerpack and Powerwall will lead to more gigafactories than Tesla’s first in Nevada.

Tesla says the initial economies of scale will drive down battery costs by 30%. The convenience factor compared with flooded batteries, the wet-cell lead acid batteries much like in your car, are immense. They have to be checked weekly, the fumes can be problematic, and there’s even a slight risk of sparks causing a fire. There are already sealed battery packs for backup and storage, but Tesla’s lithium ion technology and longevity could prove preferable to consumers. The Tesla site already has a signup page for Powerwall-intenders and says first deliveries begin this summer. You’ll buy Powerwall from a Tesla partner that can handle the entire installation. They include Treehouse, SolarEdge, and Green Mountain Power. Tesla on its site says the prices of Powerwall ($3,500 for 10 kWh, $3,000 for 7 kWh) are the selling price to installers. Since the price will be known to customers, it’s not clear if the batteries will be marked up, or if the installer will recoup its costs and profit from the installation service.