PV Gap

Marilyn Said:

what is passive energy?

We Answered:

Passive solar energy is simple unaided sunshine heat and/or light. Feel warm from standing in the sun? That's passive solar energy. It's doing nothing but landing on you, and warms you up directly. Sunlight is passive solar light.

Active solar when there's an appliance of some kind turning that passive energy into some other kind of energy. The most obvious is sunlight landing on a photovoltaic cell which produces electricity, and you use that electricity to do something like create heat with a toaster to make toast, or to light a LED lightbulb to make light. Both are still done with solar, but because there's a PV cell converting the sunlight into electrical energy, what you have is active solar.

Where is gets a little blurry is with something like solar hot water. You could argue that the water is heated passively, but many solar hot water units now don't have the acutal water that you use being heated directly by the sun, there's a frost-proof fluid used which then pipes through the water heating it.

Or a passive solar heated home. These work by having windows pointed to the sun and capturing the passive heat, and then having insulation and double glazed windows to keep that heat inside. Yes it's passive heating, but some passive building design is so sophisticated with passive COOLING as well that the building is as complex as a solar hot water system or even a PV cell, so could be argued as being an ACTIVE solar house.

Suzanne Said:

What is passive solar energy?

We Answered:

Passive solar heating and cooling represents an important strategy for displacing traditional energy sources in buildings. Anyone who has sat by a sunny, south-facing window on a winter day has felt the effects of passive solar energy. Passive solar techniques make use of the steady supply of solar energy by means of building designs that carefully balance their energy requirements with the building's site and window orientation. The term "passive" indicates that no additional mechanical equipment is used, other than the normal building elements. All solar gains are brought in through windows and minimum use is made of pumps or fans to distribute heat or effect cooling.