Passive Solar Hot Water Heating Systems
everyday explanation of passive solar water heating
The simplest way to passively heat water with the sun:
- paint a container or bucket black,
- pour water into it,
- put it out in the sunlight,
- wait a few hours..
..presto! Free hot water, compliments of Ra, the ancient Egyptian Sun God. The bucket system is a "passive" system because it does not use any moving parts or electricity.
scientific explanation
Billions of photons beaming from the sun strike the bucket's surface, thereby exciting the bucket's atoms --making them move and "spin" faster. We observe the faster moving atoms as an increase in temperature. The bucket's more excited atoms in turn excite the "H2O" water molecules. The transfer of heat is called thermal conduction and obeys the laws of thermodynamics and the scientific law of conservation of energy, not to be confused with human-legislated conservation law.
hot water from the sun
We enjoy hot water in the form of hot showers and also the important side benefits of loosening grit and grime from our skin, clothes, dishes, floors and pets.
batch collectors
Passive "Batch" collectors are a more sophisticated form of the bucket example. The collectors are black coated containers or tanks that are housed in an insulated metal box and covered with a solar glass or glazing material, and are larger than buckets. Usually batch collectors are filled with pressurized water.
strengths
Batch collectors operate without the need of "active" pumps or controls, so they don't need much maintenance. Also, because they don't have many parts, they can be the least expensive system to purchase, build, and maintain.
weaknesses
Batch collectors are not as efficient as "active" collector systems. Also, batch collectors should be installed only where freezing is not a problem, because the water feed pipes and storage tanks are prone to freeze damage. Owner participation is usually required to prevent freeze damage, by manually draining down the batch collector during near freezing weather conditions.
other passive systems
Thermosiphon Systems are a special kind of passive system that has solar panels resembling active systems.
specific systems
King Solar offers the Hydroquest ICS
batch collector with its reputation for providing decades of hot water and
high customer satisfaction. The SunBather ICS Batch
System is another popular passive system.
sizing systems
The above system works for most residential applications. For best results, systems should be matched according to energy use patterns. Sizing a domestic or commercial solar system can be a challenging exercise, regardless of system type. We can help. Send us your requirements.
Tell us:
- how the solar hot water heating system will be used. For example, will it be used in a home or as part of a boiler system in a commercial environment
- how many gallons of hot water are used per day. We can approximate by knowing how many people live in the residence, or how much heat is created per day by a boiler etc.
Contact us for a price quote. We will reply within 48 hours with a suggested set of equipment specifications to meet your alternative energy needs.