Solar Hot Water

After climate control, hot water is the second most energy-consumptive household operation. Solar water heating can reduce the energy expended by as much as 90% in most latitudes without sacrificing any hot water.

An active solar hot water system includes a traditional solar hot water heater (either electrical or propane) that is fed by a roof-mounted passive solar hot water heater. Radiant heat from the sun heats the water on the roof and insulation ensures that the heated water loses its heat as slowly as possible after the sun has set. Since the traditional hot water heater is activated by thermostat, it does not turn on when fed by hot water from the roof and is only activated when the inlet water is cooled below the activation temperature.

For tropical environments, many households forego an active system and rely on passive solar water heating and simply sacrifice the luxury of hot water when an extended period of rain makes it so that the roof-mounted heater does not get enough solar radiation to heat up, or in cases in which the entire volume of water is consumed during the night. Tank volumes typically vary between 30 and 50 gallons. Pricing for factory models range from $3500-$5000 FOB San Jose.

Osa Power and Water fabricates these same units locally in Costa Rica for pricing of $1750-$2500. For active systems an additional $750 is required for the additional hot water heater and fittings.