What is Passive and Active Solar Energy?

There’s an ongoing debate over the relative advantages of passive and active solar energy, with proponents on both sides believing their technology delivers higher utility bill savings and carbon offsets than the others.

This article explores passive vs. active solar power and how you can leverage both of these sustainable technologies to your advantage.

What Is Active Solar Energy?

This category includes all solar technologies that convert the sun’s clean energy into usable power (in the form of electricity). The photovoltaic (PV) panels you often see on residential or commercial roofs are the most famous example of active solar power. However, this category also includes the concentrated solar power (CSP) installations you often see on mega solar farms.

What Is Passive Solar Energy?

This category includes technologies and structural designs that use the sun’s natural radiation to help provide:

  • Heating during the cold winter months
  • Cooling in the hottest months of the year

In practice, tinted windows, south (or north-facing) facades, and solar water heating are all examples of passive solar power.

Which Is More Efficient: Active vs. Passive Solar Energy?

Both passive and active solar energy technologies help reduce reliance on grid electricity generated from fossil fuels. So whether you embrace active or passive solar power, you’ll start generating monthly utility bill savings and carbon offsets. And over time, both technologies will eventually pay for themselves – often many times over.

But which one pays for itself faster?

This isn’t easy to answer since the two technologies perform very different functions:

  • Active solar power is about energy generation
  • Passive solar leads to reduced consumption

There are advantages of passive and active solar energy, but which to choose ultimately depends on the return on investment (ROI) that you hope to receive:

  • Tinting windows, for example, costs a lot less than installing PV panels. However, the monthly savings from this passive solar improvement will be modest.
  • By contrast, installing PV panels can cost tens of thousands of dollars upfront. However, you’ll make that money back several times over the 25+ years of your solar panels’ warrantied lifetimes.

The only way to know which investment delivers the higher ROI is to run the numbers for your specific home or business, complete with on-site inspections from both active solar and passive solar technicians.

However, it’s a false choice since both sustainable technologies complement one another. In other words, becoming more energy efficient with passive solar can help grow the savings generated by installing PV panels – and vice versa.

What Are the Advantages of Passive Solar Energy?

Below are some of the main benefits that await you if you decide to explore passive solar power.

1. You Don’t Need Direct Sunlight

The goal is often to block out sunlight with shades, tints, and even intelligent landscaping (i.e., planting trees).

2. Passive Solar Is Often Cheaper

Passive solar doesn’t typically involve a lot of equipment or wiring. And this allows you to keep costs relatively low – depending on the scope of whatever improvements you’re making.

3. Reduce Noise Pollution

Adding trees or insulating windows helps maintain a consistent interior temperature and reduces the amount of noise pollution entering your home or business.

4. Maintenance Costs Are Low

Most passive solar solutions are set-it-and-forget-it (hence the name “passive”). You’re done once you apply a window film or plant a tree. This single upfront investment delivers decades of financial and environmental savings in both cases, all with minimal upkeep.

However, passive solar does have limitations.

What Are the Disadvantages of Passive Solar?

There’s a lot to like about passive solar. But this approach does have certain drawbacks.

1. Limited Design Options

You’re often stuck using whatever structural features already exist with passive solar. For example, maybe there isn’t a south-facing window. Or perhaps it’s not possible to alter a wall’s tilt so that it casts a shadow on the home at high noon.

Although the passive solar design is often cheaper than installing PV panels, some structural changes are either impossible or prohibitively expensive.

2. Navigating Seasonal Fluctuations

In addition to being locked into structural designs, passive solar also limits your ability to adjust to seasonal variations throughout the year. For example, the cooling shade of a recently planted tree will also reduce the amount of sunshine hitting your home during the coldest months of the year.

Fortunately, this doesn’t apply in all situations. Insulating windows, for example, prevents heat transfer – allowing you to maintain a comfortable interior temperature during the coldest and warmest months of the year.

What Are the Advantages of Active Solar Energy?

Whereas passive solar design dates back millennia, solar photovoltaic panels are a relatively new technology developed during the 1960s for NASA satellites – before becoming a consumer product by the 1980s.

Below are just some reasons why solar PV panels went from an expensive fringe technology to becoming an increasingly popular rooftop feature nationwide.

Roof top solar, angled roof

1. Substantial Utility Bill Savings

The electricity generated by your PV  panels offsets what you need to buy from the grid. As such, active solar offers a guaranteed payback period with a predictable ROI – provided that you regularly clean, maintain, repair, and upgrade your panels regularly. Much like passive solar, photovoltaic panels are mostly set-it-and-forget-it. But from cracks to dust to slipped modules, there’s a lot that can go wrong over the 25+ years of a standard PV installation’s lifetime.

2. You Can Share (and Monetize) Green Electrons

Most states have some net metering or feed-in incentive that allows you to send unused solar electricity into the grid – in exchange for utility credits or cash payments. In addition to speeding up the payback period of your investment, these incentive programs also mean you can share the clean electricity from your solar power installation with the rest of the community.

In effect, your solar energy investment helps make the entire utility grid a little greener.

3. Solar PV Can Make You Energy Independent

With solar panels on your roof (coupled with the right type of inverter), you’ll have reliable access to daytime power – even if the rest of the utility grid goes down during an outage. And by installing on-site batteries, you can also store excess solar electricity to continue powering your appliances at night.

With enough solar and storage capacity, it’s possible to completely unplug from the utility grid. Many tiny homes and facilities use this approach whenever connecting to the electricity network isn’t feasible.

4. Solar PV Offers More Design Options

There are many different design options if you choose to add solar PV panels to your home or business. Rooftop solar installations are the most popular. But ground-mounted PV systems and solar-enabled carports are also excellent choices when the roof isn’t large or strong enough to accommodate solar modules.

Moreover, there is a theoretical limit to reducing energy consumption when using passive solar design. But with active solar power generation, you can add as much capacity as you need. And want you don’t can be converted into cash payments or utility credits if you’re enrolled in a state-level net metering or feed-in tariff program.

The economic advantages of solar energy are difficult to overstate. Even still, PV installations do have certain drawbacks.

What Are the Disadvantages of Active Solar Power?

Although solar PV technology offers many valuable benefits, there are some limitations.

1. Solar PV Is Costly (Upfront)

Buying a solar PV system large enough to cover a significant portion of your energy needs will likely set you back tens of thousands of dollars upfront (even with the federal solar tax credit). Fortunately, solar financing has helped make the technology more affordable – whether you choose leases, loans, power purchase agreements (PPAs), or even property-assessed clean energy (PACE) loans.

In nearly all cases, these financing options are structured such that your monthly payments are less than what you used to pay your utility provider. And as a result, you start saving the moment your PV system becomes operational.

2. Solar Suitability Limitations

Not every residential or commercial property is suitable for solar power generation:

  • Sometimes the roof is too small or needs to be upgraded (although ground-mounted systems are an option if there’s enough yard space).
  • Sometimes the property doesn’t receive enough direct sunshine. It’s possible to reduce shading by trimming nearby trees. But if a neighboring building is blocking out sunlight, there’s not much you can do.

Community solar gardens are a potential workaround if you fall into this category. With this approach, you buy a proportional stake in a large solar PV installation nearby. The green electrons don’t necessarily reach your property, but they help offset your utility bills. And your clean energy investment also helps to green the rest of the grid.

3. Solar Power Generation Is Intermittent

The benefits of passive solar design remain even after the sun goes down. For example, the water in your solar heater stays warm thanks to insulated reservoirs and tubing. But with active solar, you need continuous sunlight to generate electricity. And this can be problematic at night, on overcast days, or even when a passing cloud goes by.

Most PV systems switch to grid electricity when there isn’t enough direct sunshine. But for critical loads, you may need to install on-site batteries if reliable; uninterrupted access to power is essential for your home or business.

Choosing the Right Solar Option for You

Now that you understand the relative disadvantages and advantages of solar energy, which technology is suitable for your situation – passive vs. active?

In our opinion, it’s a false choice since the two technologies complement (rather than compete with) one another. Both investments can independently deliver measurable utility bill savings and carbon offsets. And when you combine passive and solar together, these benefits only compound.

Equally important, joining the two technologies also reduces the upfront cost of both investments:

  • The more PV panels you add, the fewer passive solar improvements you’ll need
  • The more passive solar you add, the fewer PV panels you’ll need to power your home

Conclusion

Cleaner air, lower bills, and increased energy independence are just some advantages of passive and active solar energy. But again, these benefits only emerge if you care for your clean power investments with ongoing maintenance and upkeep. And this can prove challenging – especially with older PV systems or passive solar improvements.

For example, whom would you call to:

  • Repair a faulty solar battery?
  • Clean your PV panels of dust?
  • Fix the glazing on your windows?

At 365 Pronto, we can tell you precisely whom to call.

Our AI-powered algorithms will analyze your project’s specifications, size, location, and other variables – before instantly connecting you with the exemplary service and repair technician for the job.

To learn more about our solar matching solutions, schedule a free demo with us today.