Thermal Solar Water Heating
| Table Header | Table Header |
|---|---|
|
2 |
Reduces use of fossil fuels, thereby reducing utility expenses and increasing post energy independence and security |
|
3 |
Six to 12 months for design and procurement and one to two months for installation and testing |
|
2 |
Engineering services, solar thermal modules, substructure and mounting system for modules (roof-mount or ground-mount), and balance of systems (e.g., pumps, valves, piping, tanks) |
|
|
FAC, FIN, GEN, BPO |
Thermal solar water heating systems collect radiation from the sun to heat water with no fuel cost or GHG emissions, and with low operation and maintenance cost. A solar water heating system includes solar thermal collector panels and storage tanks.
Two types of thermal solar water heating systems are available:
- Active systems constantly recirculate water or heat-transfer fluid (used in colder climates) in an indirect circulation system.
- Passive systems do not circulate fluid and offer three different technology options: flat-plate (such as those used for swimming pools), integral collectors (such as those used for any pre-heat tank system), and evacuated tubes. Evacuated tube collectors can produce near-boiling temperatures and are particularly effective for kitchen applications, which require higher-temperature water for sanitization.
Figure 9: The components of a solar thermal system
Image Source: www.uksolarenergy.org.uk
These technologies are quickly and easily implemented and are most suitable for residential and commercial laundry and kitchen applications, where hot water demand is high.
Thermal solar hot water technology works in most climates—not just in hot, sunny locations—to achieve cost-effective results.
To determine the potential for using thermal solar water heating at posts:
- Look online for solar insolation maps (see Resources: World Solar irradiance data (solcast.com)), which show the average daily solar radiation a location is likely to receive, depending on the time of year. Note that solar thermal water heating is most cost-effective on sites with an average daily solar insolation of 4.5 kWh/m2.
- Consider that sites with lower solar insolation but high costs for conventional water heating (more than $0.02 per thousand British thermal units (BTUs) are good candidates). Sites with lower solar insolation but high avoided energy costs are also good candidates: this includes sites with electricity rates over $0.034/kWh, with poor access to natural gas, or with aging boilers.
Consider the following when identifying locations for solar thermal modules:
- Space: Ensure there is adequate ground or roof space for solar thermal modules.
- Solar access: Look for flat or tilted areas that receive little or no shading from adjacent structures and landscaping. Select south-facing surfaces in the northern hemisphere and north-facing surfaces in the southern hemisphere. Near the equator, horizontal surfaces work best.
- Security: Consult security personnel to confirm that location of and access to solar systems are not in conflict with security criteria.
- Use adjacency: Look for available surfaces nearest the most significant or concentrated uses of hot water as identified above.
- Installation: Identify areas that are already tilted toward the sun or that are off the ground, such as rooftops.
- Maintenance: Consider areas with easy access for maintenance personnel for cleaning and repair. In addition to optimizing solar harvest, tilting panels also reduces required cleaning frequency.
Payback for thermal solar water systems can be as short as one year, depending on local energy costs. Implementing simple and inexpensive strategies to reduce heat loss and wasted hot water prior to sizing a solar water heating system can help minimize the payback period.