Your Bill

How much electricity do you use?

Electricity is measured in kilowatt-hours (kWh). This is one thousand watts being used for one hour. Some examples of usage include:

>         A 100 watt light bulb burning for 10 hours

>         A 42" LCD TV (300 watt) turned on for 3 1/2 hours.

>         A computer running for 4 hours

To calculate your electricity usage in kilowatt Hours (kWh) per day, find a recent electricity bill, preferably a summer and a winter bill. Look at the information about how much electricity you used. This by itself will probably give you an additional incentive to go solar. It will also be the first thing a solar installer will ask you for.

You are probably shown the total number of kWh you used. Divide this number on your bill by the number of billing days to see your daily electricity usage.

Understand Tiers

Utilities generally increase your cost for electricity as you use more. These slices of power usage are called "tiers." As you can see below, at high tiers, you can pay more than double the amount at low tiers.

The Baseline Tier generally covers the first 10 kWh per day.

 

Tiers

 

Baseline

2

3

4

5

6

Edison

$0.12

$0.15

$0.24

$0.29

$0.34

 

LA DWP

$0.11

 

 

 

 

 

Pasadena

$0.09

$0.10

$0.11

$0.13

$0.15

$0.17

Burbank

$0.10

$0.14

$0.16

 

 

 

Glendale

$0.15

$0.18

$0.21

 

 

 

The cost for solar PV electricity, after rebates, is now approaching $.10 - $.15 per kWh, making it competitive with almost tiers all except the baseline.

You generally want to install a PV system sized to replace your highest cost electricity (the amount at the highest tier) - this will give you the fastest payback.

For PV system sizes, the number equals the kWh generated in one hour of full sun. Over a year, a 1kW system will generate 4.1 kWh of electricity per day. In summer, it will be more like 5.1 kWh per day, and in winter, it will generate 2.9 kWh per day.

Energy Efficiency

Energy conservation and efficiency measures are easier and less expensive to implement than solar. An energy efficient building will use less energy and require a smaller and less expensive solar system. Application of the 10 energy efficiency measures below in a typical home yields nearly $600 in annual bill savings, and an impressive 16% overall return on investment. The diagram below provides a representative view of the high profitability of energy efficiency upgrades. Note that the home evaluated here is located in an average U.S. climate and has a heat pump, electric water heater, clothes washer, clothes dryer, and dishwasher.

 

The example cost-effectively surpasses the 30% savings target for existing homes under PATH (The Partnership for Advancing Technology in Housing). In fact, all of these measures yield a higher return on investment than an ordinary bank account, and most are as or even more profitable than the stock market has been in recent years! The efficiency savings shown above include the effect of income taxes. This makes the savings even more attractive, because you can keep all the money you save on your energy bills, but have to pay hefty taxes on most ordinary investment income.

Energy Efficiency Upgrade

Purchase Price1

Annual Bill Savings2

Simple Payback (yrs)

Rate of Return

Fluorescent Lamps & Fixtures

$200

$80

2.5

41%

Duct sealing

$250

$95

2.6

41%

ENERGY STAR Clothes washer

$194

$66

2.9

37%

ENERGY STAR Programmable Thermostat

$107

$29

3.7

30%

Water Heater Tank Wrap (R-12)

$85

$23

3.7

28%

ENERGY STAR Refrigerator

$97

$23

4.2

27%

ENERGY STAR Heat Pump

$692

$126

5.5

19%

ENERGY STAR Dishwasher

$29

$5

5.5

18%

Air sealing to 0.5 air changes per hour

$522

$38

13.7

9%

Increase wall and attic insulation

$1,784

$111

16.1

8%

Total

$3,960

$597

6.6

16%

Total bill savings as % of baseline bill 3

 

36%

 

 

NOTES:
Assumes typical house with air-source heat pump, electric water heating, clotheswasher, clothes dryer, dishwasher. Purchase prices and annual bill savings for efficiency measures are in nominal 1997 dollars. The rate of return assumes 3% annual inflation in residential electricity prices. After-tax rates of return assume a 28% marginal income tax rate.


1Purchase price of clothes washer, dishwasher, thermostat, and heat pump measures is incremental to the price of existing "NAECA" appliance standards. All other prices reflect the full cost of the measure, including installation.
2 Bill savings assume average electricity cost of $0.088 per kilowatt-hour. Bill savings of equipment measures are relative to a NAECA standard unit.
3 Heating and cooling consumption values are from LBNL energy modeling using DOE-2; other enduse consumptions are from the U.S. Department of Energy's Residential Energy Consumption Survey (RECS).

Source: http://www.fypower.org/res/efficient-appliances/

Installers

A professional solar installer will simplify what can be a complicated process, and take care everything for you. They will verify that your site is suitable for solar, inform you about all available incentives, and guide you through the permitting and installation process. A database of registered installers, contractors, and retailers is available here:

http://www.gosolarcalifornia.org/retailers/index.html.

This site will give you and your installer a good idea of whether your site is suitable for solar. It will provide a lot of the information needed to provide estimates, including total roof area, roof area suitable for solar (including the impacts of trees and neighboring buildings).

Also make a note of anything on the roof that may shade your solar system for example any mechanical equipment, chimneys, roof decks, etc. To learn more about the process of buying a photovoltaic solar electric system go to:

http://www.energy.ca.gov/reports/2003-03-11_500-03-014F.PDF

Other resources:

If you want to find more information go to: http://www.gosolarcalifornia.org/solar101/index.html