This is an interesting time to consider adding a solar power system to your home because solar energy is no longer getting cheaper in 2021 (due to a broader and ongoing price inflation), while the range of available solar options for homes is continuing to expand. Today, your options are no longer limited to the traditional photovoltaic (PV) solar panels.
Thanks to the advancements in solar technology, you can now opt for the so-called thin-film solar panel laminates designed to adhere to standing seam metal panels or to flat roof surfaces (membranes) like PVC, TPO, EPDM Rubber, without the need for any roof penetrations. Thin film panels feature peel-and-stick adhesive that eliminates the need to drill holes in the roof.
What’s in this guide: This guide compares innovative thin-film (TF) photovoltaic laminates to traditional PV solar panels with respect to balance of system (BOS) costs, pros and cons, available options, and more.
Did you know? The cost of residential solar energy panels has dropped by over 50% since 2010. The current average cost of a residential PV solar panel system hovers between $2.80 and $3.24 per installed watt. This is before the 26% tax credits from the federal government. Note that solar investment tax credits (ITC) will be reduced to 22% in 2023, the last year of the program.
For example, today, a typical 6kW PV solar panel system costs approximately $18,000-$19,440 before the applicable federal tax credits and local incentives are applied.
Before we break down residential PV solar system options, this table offers a quick comparison.
|Type||Cost per Watt||Efficiency||Average 6kW System Cost|
|Polycrystalline||$2.80-$3.00||13% to 17%||$17,400|
|Monocrystalline||$3.00-$3.24||17% to 22%||$19,000|
|Thin film Panels||$2.00-$3.00||10% to 18%||$17,000|
What are Crystalline PV Solar Panels?
This is the traditional solar power system, so we begin with it.
These PV solar panels are photovoltaic cells, usually made from silicon formed into flat wafers. Wiring connects the cells to one another, and the entire field of cells is connected to an inverter and ultimately to the home’s electrical panel and/or the electric grid.
The cells are installed on a rack to form a panel, and the rack is mounted on the roof, the ground or other suitable location.
Options: The two primary options are monocrystalline and polycrystalline silicon.
Monocrystalline silicon, termed mono-Si, Mono and single-crystal-Si, are the purest silicon, and therefore the most efficient. Silicon ingots are cut into wafers to create the solar PV cells.
Monocrystalline solar cells can be up to 22% efficient compared to 17% for polycrystalline solar cells. Because of the better efficiency, Mono-Si panels can be smaller than poly panels and produce the same amount of electricity.
Mono-Si PV cells last longer, with most manufacturers offering warranties of 25 years.
Monocrystalline cells create more electricity in low-light conditions, and they don’t lose as much efficiency when very hot as p-Si PV cells do. However, neither are as effective in low-light conditions as thin-film PV panels.
Polycrystalline silicon cells: (p-Si, poly or multi-crystalline) are made from raw silicon fragments that are melted and poured into square frames. The wafers cut from them are very square, but are mottled in color since made from fragments.
Poly PV solar panels cost less per kilowatt hour than monocrystalline panels. Since they are less efficient, systems have to be larger. The break-even point for poly PV solar power is about 10kW systems in residential applications.
Crystalline PV costs: $2.80 to $3.24 per watt. A decade ago, the much-higher cost of monocrystalline panels made polycrystalline panels a better value, as long as sufficient rooftop space was available for the larger panels. The cost difference has narrowed, so most solar panel manufacturers prefer monocrystalline silicon for its better output to cost and the less space required.
Note: If you’re reading information that says mono-Si panels are much more expensive than poly-Si panels, the information is out of date.
Efficiency: 13%-16% for polycrystalline silicon panels; 17% to 22% for monocrystalline silicon PV panels.
Top brands of crystalline silicon PV solar panels: SunPower, LG, Solaria, Seraphim, SunSpark, Talesun and Trina Solar. Most make both mono and poly panels.
Did you Know? PV, or photovoltaic, is a word formed by the combination of photon (light) and voltage (electricity). Simply put, PV means light converted to electricity. PV technology was discovered in the 1950s at Bell Telephone.
Scientists testing silicon, an element in sand, found that it created an electric charge when exposed to light. This became known as the PV Effect. Solar power systems and thousands of other uses for the technology were born.
What are Thin-film PV Solar Laminates?
Thin film panels are flexible strips of material with cells 1/350th the size of standard crystalline silicon cells. Efficiency is very good, as discussed shortly. These products are also called TF solar cells, TFSC and TFPV.
The flexible PV cells are laminated to a polymer film featuring metallic conductors. The conductors are arrayed in a pattern to maximize solar collection.
TF solar panels have gained wide interest for use on metal roofing, as seen in the photo below. Most have peel-and-stick application, reducing installation costs.
Options: The three top thin-film solar laminates for residential use are Cadmium Telluride (CdTe), amorphous silicon (a-Si) and Copper Indium Gallium Selenide or DiSelenide (CIGS).
- Cadmium Telluride once held 50% of the global market, but the share is dropping. Cadmium is a toxic agent and of concern to manufacturers and homeowners. Still, it remains widely used TF technology for residential solar PV systems.
- Amorphous Silicon thin-film laminates are the second most-commonly used type, but that is changing. They are cheaper but less efficient than the other two. A-Si is also durable and has low toxicity. As demand for efficiency rises, a-Si is being used less often.
- Copper Indium Gallium Selenide TF laminates are on the rise in popularity due to excellent efficiency.
Pros and cons: Cost vs efficiency matter here too. CIGS combine the best cost to efficiency ratio. Toxicity concerns are minimal compared with Cadmium Telluride. However, it’s expected that CdTe will continue to be widely used in flexible solar panels using thin-film technology.
Amorphous silicon, while used in residential solar PV panels, is less efficient. It is better suited to small-scale technologies like solar calculators and the solar lights that line walkways.
CIGS thin-film PV solar power systems are the best this technology has to offer at this time. MiaSolé, for example, uses copper indium gallium selenide (CIGS) thin-film technology for low-profile installation.
Costs: $2.00 to $2.95 per watt. The total balance of system (BOS) cost is about 20% lower than the cost of traditional solar panels due to significantly lower installation costs. Read on to see the advantages of TF solar technology over panels before you make your decision.
Efficiency: High-end Thin-film PV solar laminates suitable for residential installations can range from about 14% to more than 18%.
Thin Film Solar PV vs Crystalline Silicon Panels
Thin film PV laminates offer several advantages:
- TF laminates cost less to manufacture than multicrystalline and monocrystalline solar cells and use less energy in the process.
- Thin film solar produces more energy in cloudy. partially shaded conditions and low-light periods of the year when the sun is in the southern hemisphere.
- Because they are so lightweight, installation costs are lower.
- The lightweight design, at 7-10 ounces per square foot, does not require any mounting hardware or support, so there are no penetrations through the roofing material.
- Peel and stick TF laminates install quickly on any metal roofing type while traditional solar panels require adding brackets to seams on standing seam roofs.
- TF’s flexibility is ideal for curved/domed metal roofing.
- Thin film solar PV laminates don’t lose as much efficiency as crystalline panels do in high heat.
- TF PV panels can be walked on, if necessary, without them breaking.
- Wind uplift is far less likely with thin-film solar laminates.
- The low profile of TF laminate panels is aesthetically less obtrusive than raised panels.
- Emerging TF technologies and materials promise high efficiency.
Traditional poly and monocrystalline PV solar cell panels have advantages too:
- They are more efficient, especially mono-Si panels, so are a better choice when roof space is limited. TF is quickly closing the efficiency gap, though.
- Crystalline PV panels perform best in full-sun conditions.
- Poly-Si and Mono-Si panels last longer than some TF film, though the best crystalline and TF panels offer 25-year warranties against degradation.
- Crystalline silicon panel cost drops more each year than TF, at least currently.
Did you Know? If you install a PV solar power system, you can be compensated for surplus electricity. Power generated above your home’s needs can be send to the grid and credited to you via the process called net metering.
As one homeowner said of net metering and solar, “I love standing by the power meter and watching it turn backwards in the daytime.”
The goal for many homeowners is a net-zero home using annualized calculations. That means they push as much power onto the grid during the year as they pull from it.
When Thin-film is Better
- Your home is in a northern and/or cloudy region of the country.
- On standing seam metal roofing – it is more affordable for the material and installation.
- When you have a large rooftop area available for a TF solar PV system (since TF isn’t quite as efficient as monocrystalline PV).
- When you want the panels to be low-profile and less visible.
- If your roof gets high winds.
When Traditional PV Solar Panels are Better
- Your home is in a southern and/or sunny region.
- Rooftop space is limited.
- You have an asphalt roof. If so, you should plan to install new asphalt shingles before adding solar panels, or you’ll be faced with shingles that are wearing out before the solar panels need replacing.
- When you want the best value in residential PV solar energy systems.
Money Saving Tips on your PV System
There are several ways to reduce the cost of your residential solar energy system.
- Tax credits: Federal tax credits for residential solar PV systems are in place through December 31, 2023. The credit is 26% through 2022, 22% in 2023.
- Local programs: There are currently more than 900 solar PV loan and rebate programs. Look for one where you live at the Programs page on DsireUSA.org. Choose the blue-gray Apply Filters tab on the upper right. Then: Technology > Renewal > Solar Technologies > Solar Photovoltaics. Then select Apply Filters at the bottom of the list. You’ll have more options for refining your search to find programs you can take advantage of.
- PACE loan: PACE is the Property Assessed Clean Energy Program. PACE provides loans to homeowners with payments based on the energy cost savings that should be realized with the installation of a solar PV system. Private lenders make the loans under PACE guidelines.
What Other Options Do You Have?
Thin film solar panels vs crystalline PV panels isn’t your only option. Several PV systems known as building-integrated PV (BIPV) systems are just coming to the market or have been growing market share over the last decade.
With all the hype about Tesla Solar Roof, we’ve not seen many residential installations to date… However, today there are several compelling solar tile roof alternatives available from companies like SunTegra, 3-in-1 Roof, Luma Solar, CertainTeed (Apollo II shingles and tiles), and OneRoof by SunPower.
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