Passive Solar Design vs. Active Solar Energy for Homes: Understanding the Key Differences

Updated 29 July 2025

As the demand for renewable energy continues to grow, homeowners are increasingly exploring solar energy to reduce their carbon footprint and lower energy costs. Solar energy is not just one-size-fits-all. There are two primary approaches to taking advantage of the sun's rays:

Passive Solar: where you design in strategies to use the ‘free' heat from the sun.

Active Solar: a mechanical system that allows you to harness thermal or electrical energy from the sun for use in a building.

Understanding the differences between these systems (and it's not passive vs active solar heating - you can have both!) is essential when considering the best solution for your home.

What is Passive Solar Energy?

Passive solar energy is a design approach. 'Passive' solar refers to design strategies that harness solar energy for heating, cooling, and lighting in a building without mechanical devices. The passive solar energy component is baked right into the fabric and design of the building.

Passive solar energy relies on the orientation and space planning of the building to take advantage of solar radiation and turn it into solar heat, while active solar heating systems rely on mechanical equipment to convert sunlight.

How Passive Solar Design Works

Passive solar systems rely on a building's design to collect, store, and distribute solar energy. This can include positioning windows to face south (in the Northern Hemisphere) to capture maximum sunlight during the winter months, using thermal mass (such as concrete or stone) to store heat, designing the building to take advantage of natural ventilation for cooling and air movement, as well as using shading and insulation to regulate indoor temperatures.

Passive solar energy is a design approach. 'Passive' solar refers to design strategies that harness solar energy for heating, cooling, and lighting in a building without mechanical devices. The passive solar energy component is baked right into the fabric and design of the building.

Passive solar energy relies on the orientation and space planning of the building to take advantage of solar radiation and turn it into solar heat, while active solar heating systems rely on mechanical equipment to convert sunlight.

How Passive Solar Design Works

Passive solar systems rely on a building's design to collect, store, and distribute solar energy. This can include positioning windows to face south (in the Northern Hemisphere) to capture maximum sunlight during the winter months, using thermal mass (such as concrete or stone) to store heat, designing the building to take advantage of natural ventilation for cooling and air movement, as well as using shading and insulation to regulate indoor temperatures.

This means approaching building design in a slightly different way than usual. A passive solar home requires strategies that turn the house into a thermal energy collection, storage, and distribution center: a passive solar heating system is a whole-house energy strategy.

Integrating Passive Solar into A House

Passive solar is relatively easy to integrate into the construction of homes, particularly in cool and cold climates where heating is a significant concern. There are three key elements needed to harness solar energy: collect the solar heat, store it, and distribute it.

Collecting solar heat, in the form of light, is the first element of in passive solar energy systems where the goal is to offset or even replace space heating needs. In passive solar design, the windows are the solar collectors, as opposed to the bolt-on panels that are used in active solar systems to generate electricity, or charge up solar water heaters.

Windows allow the sun's rays to pass into the building. As the light passes through the glass, it transforms from short wave (light) to long wave (heat) energy and gets trapped inside the space, where it bounces around and gets absorbed by the objects and surfaces in it. This is what's called the greenhouse effect.

One of the key parts of passive solar design is ‘store': making sure the heat that is collected through the windows stays inside the building envelope. An airtight envelope with high insulation levels make the best storage device for solar energy in a house. Keeping the heat in is the first priority of 'store'.

Windows - specifically the glass in them - are always the weakest link in the house when it comes to energy efficiency. Glass is a terrible insulator, but a great conductor. That means that windows can let as much heat out at night as they let in during the day. Passive solar relies on high performance windows with features like triple pane, low-e, argon, and insulating spacers minimize this thermal energy loss.

On the other hand, materials such as concrete floors or masonry walls can store heat during the day and release it slowly during cooler nights. This is called thermal mass, and it exposed to the sun's rays directly so that it can soak up usable heat during the day.

For consistent heating in passive solar homes, collecting and storing the heat isn't quite enough. It also needs to be distributed. Heated air rises, passive solar systems work with physics will take advantage of natural convection loops. But, that's not often enough to even out temperature differences, so fans and ducts used by central heating systems are often used to help move the heat around.

Pros and Cons of Passive Solar Design

Advantages:		Disadvantages:
Low-cost implementation, especially if integrated during the home’s construction.		Limited ability to control temperatures compared to active systems, especially in extreme weather.
No need for additional mechanical systems or ongoing maintenance.		Effectiveness is highly dependent on building orientation, window placement, and climate.
Reduces energy consumption by naturally moderating temperatures.		Retrofitting an existing home to incorporate passive solar design can be challenging and costly.
Environmentally friendly, as it relies solely on natural sunlight without electricity or fuel consumption.

What is Active Solar Energy?

Active solar energy systems use mechanical or electrical devices to capture, convert, and distribute solar energy. These systems typically involve solar panels, pumps, or fans to collect and circulate heat or electricity. Unlike passive systems, active systems require external devices for the heat transfer process.

Solar technology has many uses: electrical systems, thermal systems, room air heaters, cooling systems.

A solar thermal hot water system will include a storage tank. Solar water heating systems can be used for domestic hot water or augment thermal mass with radiant slab systems. Solar thermal is often used in pool heating systems as there's a perfect seasonal match between supply and demand.

Two Types of Active Solar Energy Systems

There are two ways to extract energy from sunlight. The first type collects light and creates electricity from ‘semi-conductor' materials (photovoltaic cells) that create electrical charges. The second type - thermal systems like solar water - works on the same principle as passive solar: it collects, stores, and distributes the sun's energy as heat.

Active solar systems rely on panels, typically installed on the roof or in other sunny locations, to capture sunlight. Solar panels use Photovoltaic (also known as PV) cells to convert sunlight into electricity.

Active solar systems that produce thermal energy use panels or tubes as solar collectors that heat fluids or air, which is then stored using a heat exchanger and circulated via piping or ducting.

Pros and Cons of Active Solar Energy Systems

Advantages:		Disadvantages:
High efficiency in converting solar energy to electricity or heat.		Higher initial costs due to the need for solar panels, batteries, and other equipment.
Can dramatically reduce or eliminate reliance on grid electricity.		Potential dependence on grid electricity during extended periods of low sunlight unless a battery storage system is in place.
Scalable to meet the energy needs of homes of varying sizes.		Requires regular maintenance of mechanical components, like pumps and inverters.
Ability to store energy in batteries for later use, providing reliability even on cloudy days.

4 Key Differences Between Active and Passive Solar

1. Energy Capture: Active systems use external devices including mechanical or electrical components to capture and distribute solar energy, while passive systems rely on building design and materials to harness sunlight naturally.
2. Cost: Active solar systems require a significant upfront investment for equipment and installation, while passive solar systems can be more affordable, particularly if planned during the home's construction.
3. Maintenance: Active systems need ongoing maintenance for mechanical parts like inverters, pumps, and batteries in solar power systems. Solar thermal systems require maintenance and replacement of pumps, heat exchangers, and storage tanks. Passive systems, on the other hand, have minimal maintenance requirements as they rely on static building features.
4. Control: Active systems offer greater control over energy output and storage, making them more adaptable to changing weather conditions. Passive systems depend entirely on the design and natural environment, making them less versatile.

What is the best type of energy for a house?

Both active and passive solar energy systems offer valuable ways to harness the power of the sun.

Clean energy, like solar power or wind power, gives individuals and society a leg up when it comes to minimizing energy usage. A solar energy system to produce electricity is more common than wind for homes, because a home solar electric system can be installed on the roof, and doesn't have any moving parts.

Passive solar does that at the design stage, so it’s definitely worth it to spend some time figuring out seasonal design features for new builds and renovations. Gather the sun’s heat to keep the interior of the house warm and deflect or reject it to keep the house cool.

Passive solar can improve the cost-effectiveness of active solar by reducing space heating loads. It does this in a couple of ways, both of which are 'by design'.

The first way is by optimizing the 'free' heat from the sun during the winter by careful window sizing and placement.

The second way is by choosing high performance windows and improving the building envelope to reduce the amount of heat loss.

Can you power your entire home with solar?

Absolutely.

That’s what the terms ‘net zero energy’, or ‘zero net energy’ refer to: houses that produce as much energy in a year as they consume. Most often, the cost effective solution is to power home with solar panels.

Solar electric systems are a good match for electrification projects where oil or gas furnaces and boilers get switched out for heat pumps. Electrification programs aim to minimize greenhouse gas emissions by reducing reliance on fossil fuels.

Active solar gets ‘bolted on’, but there still needs to be planning for orientation as well as roof size and shape to optimize a solar PV system. Management of occupant loads becomes more crucial the closer the house gets to Net Zero Energy targets.

What is the Cost of Solar Panels?

Solar panels cost money. There's no way around that. Installation costs have come down significantly over the past decade, and most experts agree that if panels are installed for $3 per Watt, there is a reasonable payback the system, based on the average costs of electricity provided by the regional utility company.

There are a range of tax credits and financial incentives for green energy that can help reduce the costs of installing solar panels.

Minimize Loads, Maximize the Investment

It's important to minimize occupant loads and create a high performance building envelope for an all-electric building brimming with energy efficiency features. Making sure the system is optimized for energy production falls to the solar company installing such a system. Look at at future energy costs, a house that generates it's own electricity is immune to price swings and, potentially, grid outages, as well.

The more the annual electricity usage goes down, the fewer solar panels needed. Energy production needs to be optimized at the design stage. One thing homeowners can do right now is look at their utility bills and see how much electricity they are using. It's relatively easy to translate energy costs associated with gas and oil use into equivalent kilowatt hours to see how much power they would use in their current situation.

Solar Panel System Components

A solar panel setup includes the collector panels, and then what's commonly called the 'balance of system', often shortened to BOS. Going with high quality solar panels with good efficiency ratings is the best investment, as more power will be generated with the same number of panels. In a grid-tied system, the next biggest expense after the panels themselves is the inverter. Net metering systems need inverters that meet utility company requirements for connection.

After installation, there are minimal maintenance costs and no moving parts.

Number of Panels

How many panels are required to generate enough electricity to bring a house to a net zero energy target is based on a few factors. First, the actual location of the house. Sunlight hours vary significantly across the continent. Second, the roof orientation, because that affects how much sunlight gets converted. Third, the pitch of the roof. Fourth, the amount of shading on the roof.

The location of the house, the roof orientation, the shading and the pitch of the roof determine how much electricity can be generated.

The power usage of the house will determine if a rooftop installation can completely power the house or not. If there is not enough power generated, look to higher efficiency panels for more energy, or ways to reduce the energy usage to fit the rooftop installation. In some areas, excess solar energy can be sold back into the grid to further reduce electricity costs. In other areas, more solar panels are not allowed. Systems can also be set up to charge (and be charged by) an electric vehicle.

Building Codes Are Moving to Net Zero

Building codes are moving us down the path to Net Zero Energy by 2050. Electrification and renewable energy systems are how we get there, once we've improve the building envelope.

Active solar is ideal for homeowners seeking higher efficiency and control over energy generation, while passive solar is a cost-effective, low-maintenance solution for energy savings through thoughtful design. The choice between the two depends on your energy needs, budget, and whether you're building a new home or retrofitting an existing one.

We say there's no need to choose between the two. Passive solar design reduces the amount of energy usage in a home and reduces reliance on fossil fuels. That can lead to an optimized load for an active system to provide enough electricity for the home via a rooftop installation. Both passive and active systems have great environmental benefits and combat greenhouse gas emissions.

Why not use both?

Learn more about passive and active solar (and wind) in our Introduction to Renewables Course.