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Meter Messenger #126 - Tesla - Next Gen EV
July 15, 2013

Issue #126
July-August 2013

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Table of Contents

Tesla - Next Generation Electric Vehicle

Is Solar a Good Investment?

How Efficient is Your Air Conditioner?

Ten Energy Saving Tips

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Tesla - Next Generation Electric Vehicle

Most of us are familiar with electric vehicles that have entered the market within the last couple of years such as the Chevy Volt and the Nissan Leaf. They offer a commuter type range and style. To compensate for its 38 mile range the Chevy Volt, for example, uses a gasoline powered engine to serve as back-up and an alternative charger. The Nissan Leaf is purely electric, claims to have a range of about 100 miles on a full charge and can go from zero to sixty in about 9 seconds.

Electric vehicles not only face the challenge of limited range but the time it takes to recharge them. If you commute to work and can charge during working hours as well as overnight at home, charge time is generally not a problem. But, what happens when you want to take a trip of several hundred miles across a couple of states? If you have to stop and wait for a full charge, your travel time gets decimated.

What if an electrical vehicle could deliver a 300 mile range on a single charge, swap batteries in less time than it takes to refuel a conventional vehicle and go from zero to 60 in 4.2 seconds? Enter Tesla's Model S - a sleek, 4-door sedan now on the scene from an independent electric car company out of Silicon Valley that is not a subsidiary of any of the big automobile manufacturers.

Drivers marvel at the smooth, aggressive acceleration of Tesla's products. The EPA has certified the 85KW version of the Model S to deliver a 265 mile range. Evolving from the 2-door Tesla Roadster, the Model S went into production with first deliveries in June of 2012. 2,650 units were sold in 2012 and an additional 4,900 in the first quarter of 2013 making the Model S the best selling plug-in electric car in the U.S. beating out the Chevy Volt (4,421 units) and the Nissan Leaf (3,695 units). Tesla increased its sales target to 21,000 for the year in April and looks to produce 30,000 vehicles in 2014.

One of the company's keys to success is the way it has overcome vehicle charging obstacles. They offering several options: standard, twin charger, Supercharging stations and battery swaps. The car's on board charger will restore full power in about 10 hours using a 120 volt outlet or an optional 240 volt twin charger can cut that time in half. Special Tesla Supercharging stations, of which there are very few around the country thus far, can deliver a half charge in a half hour or do a battery swap in less than two minutes. Tesla's goal is to have enough Supercharging stations deployed by 2015 to allow coast to coast travel via the major interstates.

How does the cost of operating an electric car compare with that of a conventionally powered vehicle? If we assume electric rates to be about 10 cents per Kwh and gas prices to be $3.25 to $3.50 per gallon, Tesla's Model S fuel cost will run about 20 percent that of a similar sized 4-door sedan that gets 22-25 mpg. The best way to track this is to use a multi-point or circuit level energy monitor that measures all of the energy going through the breaker to the charging station in your garage and keep a log of any charging fees incurred away from home.

For more information on this remarkable vehicle, check out Tesla Motors.

Is Solar a Good Investment?

Many of us dream about how nice it would be to have a miniscule electric bill, or better yet, no electric bill at all because we are generating all of the power for our home through renewable, off-grid resources such as solar or wind. In many cases these dreams can be turned into reality, but at what cost? If someone can reduce a $300 electric bill to $30 per month but must add a $500 loan payment to the family budget for the next fifteen years to do so, what have they gained?

Solar PV systems do work but require careful evaluation to determine if the economics are viable. Some of the things to consider are the average hours of sunshine per day at your location, cost of the solar panels and inverter, cost of installation, roof area needed, financing options and equipment efficiency.

Rather than go through the lengthy calculations, we'd like to point you to a handy solar estimator we link to from the Solar Power Panels page on our web site. Simply enter your zip code to begin. Continue with your electric bill rate and average monthly consumption for winter, spring, summer and fall.

The estimator will run a calculation of what it would cost to install a solar PV system capable of supplying 50% of your electrical load. Installation cost, amount to be financed, interest rate, loan period and utility inflation rate are just some of the variables you can tweak to see how the investment will pay for itself.

Calculations include federal incentives to reduce overall system cost. Output depicts a cash flow schedule that shows when the breakeven point will occur, provides loan payment information and determines monthly and annual energy savings over the 25 year life of the project.

If you are considering a solar or wind energy project, wringing out the cost variables with an estimator such can prove invaluable. It shows you what you can expect to spend and what you can expect to save. Many may find their anticipated breakeven point to be much further into the future than previously expected.

Try it out - it's a great tool: Solar Estimate

How Efficient is Your Air Conditioner?

Air conditioning system efficiency is measured with the Seasonal Energy Efficiency Rating or SEER. This rating is the ratio of total Btu (British Thermal Unit) output of a cooling season to the total watt-hour input. It is used to measure the efficiency of central air conditioner or heat pump systems as they cycle on and off throughout the cooling season. Mathematically the SEER rating is calculated by dividing the total Btu output for the season by the total watt-hours used during the season.

A second rating called Energy Efficiency Rating or EER also represents a ratio of Btu output to watt-hour input for central air conditioners and heat pumps. It differs from the SEER in that it is measured only with the unit powered on, not cycled on and off. SEER ratings will always be higher for a given piece of equipment than EER ratings by 12 to 15%. Thus, the SEER rating is used as the industry standard.

What is a good SEER rating? The lowest SEER rating for central air systems produced in The U.S. today is 13. Energy Star rated homes require a minimum SEER of 14. Residential units can have a SEER as high as 20 but come at a pricey premium. These high SEER systems often operate with much higher refrigeration pressures which can increase maintenance costs.

How much can I save by replacing my current central air conditioner with a higher SEER rating? A quick way to estimate savings is to compare SEER ratings. For example, if you find your current air conditioning system is rated at 10 SEER (check the manual to find out) and you would like to replace it with a 14 SEER unit simple divide 10 into 14 and subtract the result from one. In this case it would be 1- (10/14) = 28.6%. In other words upgrading from a 10 to 14 SEER unit would save you nearly 30% in cooling costs.

If you have a heat pump, this savings would also apply to that portion of your heat that is produced by the heat pump. However, it would not apply to the energy used by the supplemental heating strips.

Keep in mind that the 28.6% savings generated is only on your cooling and heat pump compressor cost, not your entire electric bill. To determine how much energy is being used by your air conditioning system consider inventing in a multi-point or circuit level energy monitor. For additional tips on determining air conditioner efficiency check out the SEER Rating Comparison page on our web site.

Ten Energy Saving Tips

1. If you are planning to build a house this year, locate outdoor AC condenser units on the north side of the house to keep them in the shade (south side if in the southern hemisphere). Air conditioner efficiency can drop by as much as ten percent when condensers operate in the heat of direct sunlight.

2. Check your attic insulation for holes or gaps. R-30 batts are an absolute minimum. The best option is to have insulation blown at least foot thick across your entire attic.

3. Be sure that lamps or TV sets are not running in the vicinity of the thermostat. The heat they emit can affect thermostat temperature and cause cooling equipment to run longer than necessary.

4. Use your home energy monitor track the energy saving ideas your kids act upon. Take the savings from your electric bill and use a portion to bump up their allowance - when the energy is saved.

5. Do not oversize your water heater or add a second one unless you really need it. Remember, more gallons of hot water stored means more kilowatt-hours to keep it warm.

6. Plug battery chargers for tools, phones, laptops, etc. into a power strip. Turn the strip on when you are charging and turn it off when you're done. The coils within any size charger continues to draw a trickle of power regardless of whether or not it is charging a device.

7. Turn off your computer when you are done using it. Even in energy saver or sleep modes it still draws a trickle of power as do peripherals. Consider a smart switching power strip. When you set your computer as the master, all the slaved peripherals shut off automatically when you power down the computer.

8. Whenever you take a vacation for more than three days shut off the breaker to your hot water heater and shut off the water to your house. It takes more energy to keep 40 gallons of water warm for four days than it does to reheat it. Shutting off water can save a hardwood floor or carpet if the plastic water line to the refrigerator ice maker happens to rupture while you are away.

9. When checking food in the oven, look through the window instead of opening the door. A 20-30 degree temperature loss occurs whenever the door is opened briefly. In summer, the heat released must be removed by a heat pump or air conditioner adding the the energy load.

10. Try to avoid running large heat generating appliances such as the range or clothes dryer during the middle of the day so they do not compete with the air conditioner. Use these appliances in the morning or evening when outdoor heat loads are less.

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