US commercial renewable energy developer ForeFront Power has begun operations at a solar PV installation in California, which is mounted flat directly onto the ground.
The system, installed at the City of Fresno’s Northeast Surface Water Treatment Plant, was developed by Arizona-based company Erthos. It forms part of a 27MW, three-site solar PV and battery energy storage portfolio that ForeFront developed for Fresno’s Department of Public Utilities (DPU), from which the municipal utilities provider will purchase power for its operations.
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Erthos’ technology mounts solar modules directly onto the ground, rather than arranging them on the standard steel racking systems. ForeFront claimed that since it began producing power at the Fresno site in late March, the system has outperformed its expectations by producing 101% of forecast power.
ForeFront said that it approached Erthos to use its technology in 2023, after a “combination of inflation and supply shocks caused the price of labour and materials to spike.” The technology is cheaper to install than standard solar arrays because it does not require steel racking; savings which ForeFront Power said it was able to pass onto the City of Fresno through its power purchase agreement (PPA) deal.
“After conducting our due diligence and vetting Erthos technology, we discovered that the Northeast Surface Water Treatment Plant was an optimal site for an Erthos application,” said Erinne Davis, senior project manager at ForeFront Power. “Erthos helped us avoid significant, expensive civil upgrades, as well as the cost of steel for racking and the labour to install that racking. Realising these savings on the installation is what enabled the project at this site to move forward.”
Erthos is the originator of mounting solar flat on the ground, which it calls Earth Mount Solar.
It says that taking this approach reduces the levelised cost of energy (LCOE) of a solar installation, as it removes the cost of steel racking and reduces labour costs. The company has signed some other deals for US projects, including a 180MW community solar portfolio in Texas.
By creating a continuous carpet of solar modules, the method also increases the energy density of a solar installation, enabling more electricity generation per square metre than a standard configuration where modules are spaced out in rows. The installations can also be adapted to ground contours up to 15% slope, Erthos said, which means it was suitable to the undulating topography at the Fresno site.
 The Fresno project demonstrates how Erthos Earth Mount Solar can unlock projects that might otherwise be constrained by conventional construction costs,” said Jim Tyler, CEO of Erthos. “Working with ForeFront Power, we delivered a high-density solar system designed for strong long-term performance, efficient maintenance, and lower-cost energy for the City of Fresno.”
The company also developed robotic cleaning devices which clean the modules every night.
An obvious question mark over mounting modules directly on the ground is the risk of damage. We know that hail causes significant damage to modules mounted on standard racking and tracker systems, which are able to change their angle to “stow” against hailstones. Flat modules can’t be moved to protect against hailstones.
Analysis has shown that hail is expensive; it causes 70% of losses for US solar PV projects, despite representing only 6% of total recorded incidents.

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