Blog: Welcome Australia's Global Solar Rooftop Declaration

Welcome Australia's Global Solar Rooftop Declaration — But Let's Expand Its Scope

A Follow-Up Blog by Hemen Parekh

October 12, 2026

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The Declaration: A Step Forward, But Incomplete

I have just read the news of Australia backing the goal of 150 million new rooftop solar systems globally by 2030 under the Global Solar Rooftop Declaration. This is excellent news. I welcome it wholeheartedly.

But I must also be blunt: the Declaration, as currently framed, leaves out critical opportunities. It focuses exclusively on rooftops. It ignores multi-story buildings and their unique constraints. And it overlooks the breakthrough technologies—particularly flexible printed solar films—that could transform global energy generation far beyond what traditional rooftop panels can achieve.

I speak not as a newcomer to this issue. I have been writing and advocating on solar energy for nearly a decade. Let me share my concerns, backed by evidence from my own published work.

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The Core Problem I've Been Documenting: The Rooftop Space Crisis

For years, I have highlighted what I call the rooftop insufficiency problem. In November 2020, I published a blog titled "Reinvigorating Rooftop Solar Power" in which I made this point starkly:

"Main constraint for rooftop solar power generation is availability of big enough roof (terrace) area. To generate 20 KW, you need 2000 sq ft of solar panels. 10 flat owners (in 5 story house), each needing 20 KW, would need 20,000 sq ft of terrace - not available."

This is not an abstract problem. This is the reality in every major city on Earth.

Consider Mumbai, Delhi, Bangalore, Shanghai, Tokyo, New York, London, São Paulo:

• A typical apartment building with 10-20 units has a roof area barely sufficient for 10% of residents' energy needs

• Urban real estate is precious

• Rooftops are shared resources with competing uses (water tanks, air conditioning units, telecommunications equipment)

• Multi-story residential buildings dominate urban housing in developing and developed nations alike

Result: Billions of urban residents have no practical way to install rooftop solar, even if subsidies are offered.

This is why India's ambitious PM Surya Ghar Yojana—which I have closely followed and written about—has struggled to achieve its targets in cities. In December 2024, I published "Fine: But there is not Enough Roof!" documenting exactly this problem:

"At present, people living in apartments can't avail the scheme under which Centre provides subsidy of up to 40% of the cost of installing solar panels on rooftop as each individual beneficiary needs around 300 sq ft contiguous roof for generation of 300 units per month."

The Ghaziabad Development Authority's mandate to add solar panels to residential plots only works for single-family homes on large plots. It does nothing for apartment dwellers in cities.

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Where the Global Declaration Falls Short

The 150-million-rooftop target is ambitious. But here is what it implicitly assumes:

1. Rooftops exist and are available – They do not, in densely populated urban areas

2. One roof = one family – In cities, one roof serves 10-20 families

3. Rooftops are the only surface – They are not

4. Traditional PV panels are the only technology – They are not

The consequence: The Declaration, as currently framed, will primarily benefit rural single-family homes, agricultural land, and low-density suburban areas. It will do little for the billions of urban apartment dwellers who have the highest energy consumption and the greatest need for renewable solutions.

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The Multi-Story Building Problem: A Massive Blind Spot

Let me be very specific about what I mean by "enlarging scope."

In December 2024, I sent a letter to India's Prime Minister titled "Dear PM: Here is how to take Surya to Cities" in which I raised this exact issue:

"Pointing out that urban middle class families living in apartments are not getting the benefits of Surya Ghar Muft Bijli Yojana, Prime Minister Narendra Modi on Thursday asked officials to find ways out so that they can avail the scheme."

The problem is structural, not solvable by rooftops alone.

Here is what I urge the authors of the Global Solar Rooftop Declaration to do:

RECOMMENDATION 1: Expand the Declaration to Include Building Facades

Multi-story buildings have facades. In modern cities, these facades are increasingly made of glass or materials that could support solar technology. The solar energy potential of building facades is enormous and largely untapped.

I proposed this solution back in November 2020 when I wrote:

"Such transparent sandwich panels were to replace normal glass windows of a building. Under such a scenario, terrace area will not remain a limitation! All the windows of all the flats (apartments) can generate power – enough for each flat."

This is not theoretical. A 27-year-old inventor, Carvey Maigue, won the Dyson Prize in 2020 for developing exactly this concept—panels that capture UV light (which penetrates even on cloudy days) and convert it to electricity. These panels can be integrated into building windows and facades.

The Declaration should explicitly include solar window technology and building-integrated photovoltaics (BIPV) as targets for 2030.

RECOMMENDATION 2: Embrace Flexible Printed Solar Films

This is where I have been most vocal, and where I believe the Declaration has the greatest opportunity.

In February 2022, I wrote to India's Foreign Secretary and Cabinet Ministers urging the government to adopt flexible printed solar film technology. The blog post was titled "Procuring Technology for Printed Solar Film."

Here are the key facts about this technology (developed by Professor Paul Dastoor at the University of Newcastle, Australia):

TECHNOLOGY CHARACTERISTICS:

• Ultra light-weight – Can be applied to any surface

• Ultra flexible – Can conform to curved and irregular surfaces

• Recyclable – Made 99% from PET plastic

• Cheap to manufacture – Production cost less than $10 per square meter

• Rapid to produce – Commercial equipment can produce kilometers per day

• Can be painted on ANY surface – Roofs, walls, facades, even pavements

THE GAME-CHANGER: Unlike rigid rooftop panels, flexible printed solar films can be pasted on the outer walls of buildings. This transforms every building in the world from a solar-blind structure into a potential power-generating asset.

Imagine this: A 10-story apartment building in Mumbai, with outer walls of 5,000 square meters, could generate enough solar electricity for hundreds of residents—using technology that adheres to walls, does not require structural changes, and can be installed in days rather than months.

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Where I Proposed This: My Trail of Advocacy

Let me document my published positions on this:

BLOG 1: "Reinvigorating Rooftop Solar Power" (November 25, 2020)

http://myblogepage.blogspot.com/2020/11/reinvigorating-rooftop-solar-power.html

I warned about the roof-space crisis and proposed innovations including UV-capturing panels for building windows.

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BLOG 2: "Procuring Technology for Printed Solar Film" (February 18, 2022)

http://myblogepage.blogspot.com/2022/02/procuring-technology-for-printed-solar.html

This was my direct appeal to India's government to acquire printed solar film technology from Professor Paul Dastoor's team at Newcastle. I noted:

"Printed solar is cheap to manufacture, at a production cost of less than $10 per square metre and rapid to produce, with commercial scale equipment capable of producing kilometres of material a day. With over 99 per cent of the panels consisting of PET, the material can be recycled - a distinct advantage over traditional silicon panels."

I specifically urged:

• Consider extending India's PLI (Production Linked Incentive) scheme to organic printed solar film

• Invite Prof Paul Dastoor to set up a manufacturing facility in India with capacity to produce 100 million square meters per year

• Supply all of India's 30 million concrete/pucca buildings with enough film in 3 years

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BLOG 3: "Fine: But there is not Enough Roof!" (December 1, 2024)

http://myblogepage.blogspot.com/2024/12/fine-but-there-is-not-enough-roof.html

Four years after my initial proposal, I was still documenting the rooftop insufficiency problem. I wrote:

"In my earlier post, I proposed extending terrace slabs and parapets in urban buildings to accommodate solar panels effectively, acknowledging the challenge of limited terrace space for solar installations."

And I added:

"Encouraging housing ministries to revise building codes aligns with the systematic changes needed to promote solar energy integration in urban infrastructure."

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The 2022 Proposal to Government of India: Still Waiting

In February 2022—nearly four and a half years ago—I sent a formal proposal to India's Cabinet Ministers and Foreign Secretary urging them to adopt printed solar film technology. I suggested inviting Professor Paul Dastoor to establish manufacturing facilities.

As of today, October 2026, this has not happened.

Yet the technology has continued to advance. Companies like Kardinia Energy have commercialized it. The potential for global deployment is immense.

Why has this not been acted upon? I suspect it is because:

1. Policymakers think only in terms of traditional rooftop panels – The mental model is locked in

2. The technology is genuinely novel – It falls outside conventional solar industry categories

3. Supply chain dependencies persist – Governments continue to rely on imported crystalline silicon panels rather than pioneering domestic alternatives

4. Innovation in energy is slow – Even when a breakthrough is available, institutions take years to adopt it

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What I Urge the Global Solar Rooftop Declaration Authors to Do

The Declaration is laudable. But it must be reframed and expanded. Here is my specific proposal:

1. RENAME THE INITIATIVE

From: "Global Solar Rooftop Declaration"

To: "Global Building-Integrated Solar Declaration" or "Global Solar-Active Buildings Initiative"

2. EXPAND THE SCOPE TO INCLUDE:

✓ Traditional rooftop panels – Continue pursuing the 150-million target

✓ Building facades and walls – Include solar window technology and BIPV systems

✓ Flexible printed solar films – Explicitly encourage adoption for wall coverage

✓ Pavement and ground-level solar – Integrate solar pavements (like PLATIO) into the target

✓ Multi-surface integration – Any surface exposed to sun should be considered

3. SET SPECIFIC TARGETS BY SURFACE TYPE:

• 150 million rooftop systems (current target)

• 500 million square meters of building facade coverage (vertical surfaces)

• 1 billion square meters of flexible printed solar film (by 2035)

• 50 million square kilometers of pavement coverage (roads, parking, pathways)

4. TECHNOLOGY PRIORITIES:

• Support printed solar film manufacturing on a global scale

• Facilitate technology transfer from Australia to developing nations (Australia is leading in this field!)

• Streamline building codes to enable facade and wall solar integration

• Fund R&D into next-generation flexible and lightweight technologies

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The Numbers: Why This Matters

Let me make the economic case:

CURRENT APPROACH (rooftops only):

• 150 million systems by 2030

• Limited to single-family homes, agricultural land, industrial facilities

• Misses 50% of urban population (apartment dwellers)

EXPANDED APPROACH (buildings-integrated):

• 150 million rooftop systems + 1 billion square meters of facade coverage

• Includes urban multi-story buildings

• Reaches 95% of global population

• Dramatically accelerates carbon reduction targets

EXAMPLE: If every apartment building globally (estimated at 500 million buildings) were covered with just 10 square meters of flexible printed solar film per unit, that would generate:

• 5 billion square meters of solar surface

• ~5 billion kWh of generation capacity globally

• Equivalent to dozens of major coal-fired power plants

And because printed solar film costs less than $10/square meter to produce, the capital investment would be far lower than equivalent rooftop panel capacity.

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A Personal Plea to Declaration Authors

I have spent nearly a decade advocating for expanded solar solutions. I have watched governments miss opportunities. I have documented technologies that could transform global energy generation, only to see bureaucratic inertia prevent adoption.

Please do not let the Global Solar Rooftop Declaration repeat this mistake.

The world will not meet climate targets with rooftops alone. Urban populations are growing. Buildings are getting taller and more densely packed. Rooftop real estate is precious and finite.

But building facades are infinite. Walls are infinite. Every structure on Earth has vertical surfaces.

The technology to harness these surfaces exists today. Flexible printed solar films are not future science—they are current technology, ready for deployment and scaling.

I urge the authors of the Declaration to:

1. Expand the scope beyond rooftops

2. Explicitly include multi-story buildings

3. Prioritize flexible printed solar film technology

4. Set targets for building-integrated solar by surface type

5. Establish technology transfer mechanisms so that all nations can access and manufacture these solutions domestically

Australia is leading in printed solar film innovation. Australia should lead in a global Declaration that embraces this technology at scale.

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Conclusion: Let's Finish What We Started

The Global Solar Rooftop Declaration is a beginning. It is not the end.

For years, I have pointed out the gaps: rooftops are not enough, multi-story buildings are ignored, and revolutionary technologies are overlooked.

Now is the time to correct course.

Let us create a truly global solar initiative—one that recognizes that every building, every wall, every surface has solar potential. And let us deploy the technologies we have already developed to unlock that potential.

The sun does not shine only on rooftops. Neither should our solar strategy.

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Hemen Parekh

October 12, 2026

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SOURCES & REFERENCES

1. Reinvigorating Rooftop Solar Power

Date: November 25, 2020

URL: http://myblogepage.blogspot.com/2020/11/reinvigorating-rooftop-solar-power.html

Summary: Documents the rooftop space constraint; proposes UV-capturing window panels

2. Procuring Technology for "Printed Solar Film"

Date: February 18, 2022