Tandem PV is racing to deliver the next leap in solar technology with high-efficiency tandem perovskite-silicon modules that promise to transform utility-scale solar economics. But unlike many cleantech startups still stuck in the lab, Tandem PV has already raised $50 million in Series A funding and debt to build its first commercial demonstration facility in the San Francisco Bay Area.

Saritha Peruri, Tandem PV’s Vice President of Commercialization, took some time to share how Tandem PV structured its capital stack and is derisking its technology to attract investors. 

Equity + Debt: Building a Balanced Capital Stack

Tandem PV’s $50 million round combined equity and debt. The Series A was led by Eclipse Ventures and supported by strategics like Constellation Energy, catalytic capital like Trellis Climate (a part of Prime Coalition), and luminaries like Tom Werner (former CEO of SunPower).

On the credit side, Tandem worked with Stifel for venture debt and several different lenders for equipment financing. A portion of the venture debt replaced an earlier facility, and the equipment financing was non-recourse, secured by commercial off-the-shelf (COTS) thin-film manufacturing equipment.

Key Insight: Early-stage venture debt often hinges on a strong lead investor. In Tandem PV’s case, Eclipse’s ~$5 billion under management provided sufficient confidence for lenders.

First-of-a-Kind Equipment Financing: Why COTS Matters

One of Tandem PV’s most unique achievements was securing 100% equipment financing, which is rare for an early-stage manufacturer. This was possible because their process relies on COTS thin-film solar tools, making lenders comfortable with the equipment’s liquidation value.

Terms:

• 6 term sheets considered, 3 selected: CSC, Farnam, and Oakridge
• 24–36 month lease periods with renewal options 
• Standard equipment financing interest rates (16-20%)

While the cost is steep, this financing allowed Tandem PV to minimize equity dilution and preserve ownership in a highly capital-intensive business. It also extends the cash runway by reducing the significant initial cash outlays for the equipment.

Key Insight: FOAK companies can unlock equipment financing earlier by leveraging COTS solutions. Lenders focus on cash balances and collateral value, not future offtake agreements.

Derisking for Investors: Strategy in a Skeptical Market

Raising capital for solar manufacturing in the US is not for the faint of heart. Tandem PV faced headwinds from investors burned by Cleantech 1.0 and a global narrative that assumes China’s dominance in low-cost solar modules.

Their answer? Focus on US market dynamics and policy tailwinds. The US is now the cheapest place in the world to manufacture solar panels, thanks to the 45X tax credit. Tandem PV’s product, with ~28% efficiency, delivers 30–40% more power per module, which directly reduces land, labor, and balance-of-system costs.

Key Insight: Tandem PV didn’t chase a green premium. Instead, they went after an offering of more power, at the same price. In a market where utility-scale developers pay 2.5-3.5x more per watt (and > 4x more for domestic content) in the US than abroad, this resonated.

Leadership for the Scale-Up Phase

As Tandem PV transitions from R&D to manufacturing, the company has built a leadership team designed for execution. CEO Scott Wharton, a five-time startup and scale-up veteran, joined most recently from Logitech, where he took an insignificant business line from tens of millions of dollars to a billion dollars and launched 100+ new hardware products. Since stepping in, he’s taken over external communications and fundraising, allowing co-founder Colin Bailie to focus on technology. As a result, Tandem has seen the efficiency of its modules increase at a dramatic rate–nearly 1% per quarter for almost two years.

Wharton has also brought in seasoned experts across supply chain, manufacturing, and commercialization. Everyone on the leadership team has 20-40 years of relevant experience. The board has also evolved, with Eclipse’s Greg Reichow (ex-SunPower, Tesla) joining to support manufacturing scale-up.

Key Insight: Scaling climate hardware requires a leadership team built for the job. Founders should ensure their team and board match the phase of the company.

Modular Scale-Up: From R&D to Gigascale

Tandem PV is scaling methodically. Their newly leased facility will host a demonstration line, which represents a 100x scale-up from their R&D facility. Next comes a 10x increase to a high-volume line, followed by another 10x expansion to gigawatt-scale via modular replication. Once the first high-volume line is operational, little to no tech and scale-up risk is left, paving the path to project-level financing. As volumes grow from the demonstration line, Tandem PV anticipates using purchase orders and advanced market commitments to support Series B. 

Key Insight: Modular growth derisks scale-up for both founders and investors. Focus on milestones that validate technology while keeping capital needs manageable.

Avoiding the Chicken-and-Egg Trap

Many hardware startups struggle to secure funding without customers, and vice versa. Tandem PV broke this cycle by: 1) using lenders that don’t require offtake agreements, and 2) selling small volumes so that buyers don’t require a warranty. Their early utility-scale partners buy limited volumes that don’t jeopardize project bankability, but build confidence for larger purchases in the future.

Tandem PV can fund the first high-volume line the same way it is funding the demo line (i.e., venture debt and equipment financing) and not get slowed down by the need to secure binding commercial contracts to unlock credit.

Why it Works:

• Demonstration line volumes are just large enough to give early customers confidence in the product, but not so large that they require a warranty (or insurance for that warranty).
• Venture debt and equipment financiers typically don’t require customer commitments.

Key Insight: Founders can avoid the “chicken-and-egg” by aligning early production with manageable customer risk. Using lenders that don’t require offtake agreements and selling small volumes such that buyers don’t require a warranty are the two ways Tandem PV avoids the chicken/egg trap.

Capital Planning: Looking Ahead

With margins > 50% (even without 45X), Tandem PV expects rapid payback on its capex of ~2 years per line. This means future expansion could likely bypass traditional project finance, favoring equity-led builds with quick refinancing.

But there’s a geopolitical wildcard: if 45X disappears, Tandem PV is prepared to shift manufacturing abroad.

Key Insight: Project finance is often considered the holy grail for infrastructure, but is not always a good fit, as it tends to demand more time and complexity compared to raising equity. Founders should build flexibility into scale-up plans, including geographic agility.

Final Thought: Building With Foresight

Saritha Peruri draws from 20+ years of relevant experience in the energy sector, spanning project finance, project development, and power marketing. By leveraging her vast network, she is able to validate every move with industry insiders–from solar tax equity leads at major banks to insurance providers to EPCs to independent engineers–and help Tandem PV navigate FOAK territory with precision.