Bonnell Motors had already made room for electric vehicles. The family-owned Ford dealership in Winchester, Massachusetts, had installed charging stations for its customers and the public. Solar was the next investment. It came with a $1 million bill. The interesting part of the story is how that bill reached someone willing to finance it.
- Sunstone puts commercial financing inside the contractor’s sales process.
- Business borrowers can own their solar equipment while spreading the cost.
- Its expansion now includes standalone batteries and broader property improvements.
The introduction came from 621 Energy, the installer. Sunstone Credit supplied financing, and the installation was completed in three months, according to the company’s July 2024 announcement. The dealership’s president reported immediate electricity savings. A car dealer, an installer and a financing platform had each handled a different part of the same decision.
01The sale that goes missing
Sunstone’s premise is that a worthwhile commercial solar project can stall between the proposal and the payment. A smaller business may lack the financing options available to a large corporation. Paying cash competes with everything else the owner might do with that money. An attractive roof does not automatically make an attractive loan application.
Co-founder and CEO Josh Goldberg had encountered this problem from the installer’s side. His background includes Astrum Solar and Sunlight Financial, the residential solar finance company he co-founded with others. In a July 2026 Sunvoy interview, he recalled commercial customers who wanted solar but faced a choice between paying cash and arranging bank financing themselves.
The bottleneck was visible long before Sunstone existed. Goldberg and co-founder Wilson Chang brought solar experience; the broader founding team brought capital-markets and credit experience. Sunstone launched in late 2021, concentrating on businesses that wanted to install and own solar without needing an investment-grade credit rating. That choice located the company between residential lending and larger project finance.
02Keep the loan inside the conversation
The installer begins the application. The borrower supplies information online. Sunstone reviews the credit and project, while the partner can follow progress. Financing becomes another part of selling the system, with a visible route from proposal to decision. The contractor keeps the customer relationship rather than hoping a separate trip to a lender ends happily.
- 01ContractorSelects an offer and initiates the application
- 02BusinessCompletes the application and uploads documents
- 03SunstoneReviews credit and project; shares status
- 04FundingDeveloper receives payment, less fees
This arrangement also explains Sunstone’s expertise. A solar loan involves a business’s creditworthiness and the equipment’s economic value. The leadership includes former installers, commercial-credit specialists and technology executives. Chief Risk Officer Mike D’Andrade brings more than 20 years in small-business lending. Chief Technology Officer Sumbul Alvi’s remit includes simplifying and automating the processes connecting borrowers and partners.
Sunstone’s place in the market is as a financing platform with institutional backing. Cross River’s 2022 partnership included originating loans and connecting its banking infrastructure through APIs. Forbright also backed the loan portfolio. In 2024, Sunstone added a program with M&T Bank and financing arrangements with equipment-finance company DLL. Software needs capital on the other end.
03Borrower-friendly still has a price
Sunstone advertises solar terms of five to 20 years and up to 100% financing. The system itself secures the solar loan, rather than the property. Personal guarantees are used on a limited basis. For an owner already carrying a mortgage, the collateral distinction can matter as much as the payment schedule.
The business earns fees in the transaction. Its FAQ says developers pay a percentage of the loan amount, with the percentage varying by term and interest rate. Sunstone pays developers directly after deducting origination fees. The economics therefore deserve attention on both sides of the proposal: what the borrower pays and what the contractor receives.
Compared with cash, borrowing preserves money for other uses but creates repayment obligations. Compared with a lease or power purchase agreement, the ownership loan puts the system in the business’s hands. Neither comparison settles the decision by itself. Actual rates, project performance and the borrower’s circumstances determine whether ownership pencils out.
04A billion dollars, carefully read
The company raised a $20 million Series A in January 2023, led by a Greenbacker-affiliated fund, to support hiring and technology. It later acquired commercial solar lender ORKA Finance. That January 2024 deal brought contractor relationships and lending expertise into Sunstone; key ORKA team members joined as advisers.
In August 2025, a California business’s $1 million solar-and-storage application carried the platform past $1 billion in applications. It is a useful measure of demand entering the system, with a specific limitation: an application is still a request. Treating that milestone as a billion dollars lent would turn a revealing number into a misleading one.
05The ceiling, then the next room
For years, Sunstone’s solar offering stopped at $6 million. Demand above that boundary changed the product. In April 2026, it announced a Large Loan Program extending eligibility to $30 million. The old ceiling had excluded customers with larger projects, even when they wanted the same financing experience.
“We have consistently seen demand from customers with projects above $6 million, and for years we had to turn them away.”
Josh Goldberg · April 2026
Expansion also went sideways. SOL, launched in October 2025, finances standalone commercial batteries, with original terms up to 10 years or the battery’s warrantied life. The current website includes roofing, HVAC, EV charging and other property improvements. Sunstone says contractors in those trades faced the same commercial financing gap it had encountered in solar.
The idea another business can copy is precise: find the moment a willing customer leaves the sale to solve a financing problem, and improve that handoff. It still depends on credit approval and a viable project. Tenants need landlord consent and sufficient lease time. A smoother application cannot rescue weak economics. For the right borrower, it can help a sensible proposal become equipment that actually gets installed.