On average, one Sunfire Solar Water Heater prevents about 20,000 lb. of CO2 from entering the atmosphere per year and we have the hard data to prove it. Reports from our customer's electric utility companies show that one Sunfire Solar Water Heater saves 695 kWh of electricity over the course of 28 days. Over the course of a year, then, one Sunfire Solar Water Heater will save 9,057 kWh of electricity (365 days/28 days = 13.0357, 13.0357 * 695 kWh = 9057 kWh). Since 1kWh = 2.2 lb. CO2, 9057 kWh = 19,925 lb. CO2. To reiterate, just one Sunfire Solar Water Heater prevents about 20,000 lb. of CO2 from entering the atmosphere every year.
See the table for a listing of average daily total solar radiation in several U.S. Cities. The amount of sunlight striking the collector (or irradiance) is an important factor in how much energy the collector can produce. Also important is how much the energy output of the collector declines as the sunlight declines. Irradiance is measured in megajoules per square meter per day (or in Btu per square foot per day).
Average Daily Total Solar Radiation for U.S. Cities
| City | MJ/m²·day | MJ/m²·day | Btu/ft²·day | Btu/ft²·day |
|---|---|---|---|---|
| 23° Tilt | 45° Tilt | 23° Tilt | 45° Tilt | |
| Albuquerque, NM | 23.58 | 23.42 | 2076 | 2062 |
| Apalachicola, FL | 18.13 | 17.50 | 1596 | 1541 |
| Atlanta, GA | 16.62 | 16.12 | 1463 | 1420 |
| Baltimore, MD/ DC | 14.79 | 14.75 | 1302 | 1299 |
| Billings, MT | 15.91 | 16.58 | 1401 | 1460 |
| Birmingham, AL | 16.25 | 15.76 | 1431 | 1388 |
| Boise, ID | 17.54 | 17.91 | 1545 | 1578 |
| Boston, MA | 11.41 | 11.62 | 1005 | 1023 |
| Burlington, VT | 12.87 | 13.07 | 1134 | 1151 |
| Casper, WY | 18.96 | 19.80 | 1669 | 1743 |
| Charleston, SC | 14.91 | 14.73 | 1313 | 1297 |
| Charleston, WV | 13.12 | 12.81 | 1155 | 1128 |
| Charlotte, NC | 16.96 | 16.67 | 1493 | 1468 |
| Chicago, IL | 14.74 | 14.80 | 1298 | 1302 |
| Cincinnati, OH | 13.50 | 13.20 | 1189 | 1164 |
| Concord, NH | 12.00 | 12.09 | 1057 | 1064 |
| Dallas/Fort Worth, TX | 17.42 | 17.44 | 1533 | 1536 |
| Denver, CO | 20.24 | 20.89 | 1782 | 1839 |
| Des Moines, IA | 14.87 | 15.25 | 1310 | 1343 |
| Detroit, MI | 12.78 | 12.72 | 1125 | 1120 |
| Fairbanks, AK | 2.62 | 3.04 | 231 | 268 |
| Fargo, ND | 14.46 | 14.90 | 1273 | 1319 |
| Greenville, SC | 17.08 | 16.79 | 1503 | 1478 |
| Hartford, CT | 12.35 | 12.37 | 1087 | 1089 |
| Honolulu, HI | 19.24 | 17.67 | 1694 | 1556 |
| Houston, TX | 16.28 | 15.49 | 1434 | 1364 |
| Indianapolis, IN | 13.71 | 13.52 | 1208 | 1191 |
| Jackson, MS | 17.17 | 16.61 | 1512 | 1463 |
| Las Vegas, NV | 24.16 | 24.14 | 2127 | 2126 |
| Little rock, AR | 17.31 | 16.94 | 1524 | 1492 |
| Los Angeles, CA | 20.18 | 19.87 | 1777 | 1749 |
| Louisville, KY | 15.16 | 14.86 | 1335 | 1309 |
| Memphis, TN | 16.76 | 16.30 | 1476 | 1436 |
| Miami, FL | 17.70 | 16.81 | 1559 | 1480 |
| Milwaukee, WI | 13.46 | 13.70 | 1185 | 1206 |
| Minneapolis, MN | 13.73 | 14.08 | 1209 | 1240 |
| New Orleans, LA | 17.15 | 16.41 | 1510 | 1445 |
| New York, NY/Newark, NJ | 14.16 | 14.12 | 1247 | 1244 |
| Norfolk, VA | 16.57 | 16.30 | 1459 | 1435 |
| Oklahoma City, OK | 18.40 | 18.16 | 1620 | 1599 |
| Omaha, NE | 16.45 | 16.89 | 1449 | 1485 |
| Philadelphia, PA | 13.96 | 13.87 | 1229 | 1221 |
| Phoenix, AZ | 23.55 | 23.08 | 2073 | 2033 |
| Portland, ME | 11.97 | 12.24 | 1054 | 1078 |
| Portland, OR | 12.00 | 11.94 | 1057 | 1051 |
| Providence, RI | 13.00 | 13.10 | 1145 | 1153 |
| Sacramento, CA | 18.80 | 18.69 | 1655 | 1646 |
| St. Louis, MO | 16.10 | 16.02 | 1418 | 1411 |
| Salt Lake City, UT | 19.06 | 19.47 | 1679 | 1714 |
| Seattle, WA | 11.65 | 11.63 | 1026 | 1024 |
| Shreveport, LA | 17.39 | 16.79 | 1531 | 1478 |
| Sioux Falls, SD | 15.12 | 15.63 | 1331 | 1376 |
| Syracuse, NY | 11.40 | 11.29 | 1007 | 995 |
| Topeka, KS | 16.83 | 16.91 | 1482 | 1489 |
| Wilmington, DE | 14.49 | 14.44 | 1276 | 1271 |
The values listed in this table are based upon TMY data for each of the cities listed. The data for the tilted surface radiation was processed using the TRNSYS 13.1 radiation processor with the Hay and Davies tilted surface radiation model. The source for this table can be found here