When considering the switch from natural gas to solar electric water heating, I would have to replace a natural gas water heater with an electric solar water heater. This involves a) finding a unit that will fit the needs of this property, b) finding a supplier and c) having a certified vendor install the unit. As a residential customer, I don't really care about the qualitative benefits (see pros and cons of solar below) of using sustainable energy. At the end of a billing cycle, it's all about the monthly bill and the lifetime cost of ownership of the unit. If I can get the meter to tick backwards, that'd be a big plus, but it's not the primary driver for research into this household appliance.
The case for solar
Year | Cost of Gas | Gas avg/month | Cost of Electricity | Electricity avg/month |
2010 | $614 | $50 | $249 | $21 |
2011 (thru July) | $385 | $55 | $155 | $22 |
To look at actual water heater consumption, one would probably have to compare summer months to winter months. It does snow here and only a few days a year. During the winter, the thermostat is set to 62 degrees F. During the summer, it's been so mild, bordering on chilly, that I haven't turned on the a/c. The graph below shows annual natural gas and electricity costs; where energy consumption is a direct correlation to cost.
When I think about it in this context, I don't really have a data-justified case to add a solar water heater since I'd still be consuming natural gas to heat the home. Natural gas consumption has already declined month-over-month since installing the programmable thermostat (a unit that has paid for itself in energy savings vs regular usage). I haven't done nearly enough calculations to proceed further.
Pros:
- Zero emissions; no pollution
- Quiet energy production
- Installation in remote locations more cost-effective than high voltage wires
- Able to use existing footprint (e.g. angled or flat rooftops)
- Unlimited energy eventually pays for the installed unit(s)
- Less dependent on fossil-fuel-dependent energy (e.g. coal, nuclear)
- SmartGrid, NetMetering eligible
- Cash incentives from regional utility providers (see below)
- Steep (initial) cost of the solar cells and/or panel array
- Pollution in dense metro areas can affect collection efficiency of the panels
- Effective during daylight hours; significantly less available "energy" during winter months
- Collector efficiency is affected by severe weather conditions (snow, hail, blizzard blackout conditions)
BPA Factsheet [PDF]
Solar-brewed beer at Lucky Labrador Brewing Company
Weatherization Specifications Manual
Calculator: Solar Water Heating
HomePower Magazine
Database of State Incentives for Renewables & Efficiency
Energy Trust of Oregon Residential Promotions
Northwest Natural Residential Promotions