Floating Solar: A Q&A with Cohoes Planners
Cohoes has been working to build and own a floating solar array on its reservoir. The 3.2 megawatt array will cover 100% of Cohoes’ municipal electricity needs, from street lights to buildings, with about 40% left over for other uses. We spoke with Cohoes’ Joe Seman-Graves and Tess Drauschak to dive into this unique local project.
What makes floating solar more attractive than ground-mounted solar?
For us, we don’t have a lot of land. We had a lot of energy service companies coming in a few years ago that wanted to convert and purchase our streetlights and build a project off of future savings. The streetlights gave us a good understanding of how these companies model their contracts and financial projections, and we had a lot of questions and pushback on those numbers. A lot of our buildings are historic, so we can’t mount arrays on roofs, and we don’t have a lot of parking lots, either. Eventually, we realized that we’ve got 10 acres of water in the middle of our city, fenced in and secured.
The upfront cost is a bit more expensive because this is a new technology in the state but, once you get past that, we’re probably saving quite a lot of money. Water typically has a cooling effect, so the solar panels produce about 18% more than traditional panels just because they’re on water. It also saves money by reducing algae growth by covering the water. We spend about $150,000 on chemicals to help get the algae out of our reservoir and then we treat those chemicals on the back end to get the chemicals out before it’s drinking water. We don’t have an exact estimate of the cost savings on the back end, but we expect it to be substantial.
Are there any concerns about how the solar array will impact Cohoes’ water quality?
That was what we were most concerned about at the beginning, because this is a relatively new technology and we can only know what we know. We asked manufacturers and engineers about it early on, but they make money when they sell or design these, so we looked into it ourselves by visiting a very similar array in Sayreville, New Jersey that’s almost nine years old. To say that they had no concerns wouldn’t be accurate, but they had as few as you could ever expect. They are mindful of the ongoing degradation of the materials, but everything they’re using is approved for drinking water already. We’re also using bifacial solar panels, which means that they’re completely encapsulated in glass. Unless a storm shatters them, which we haven’t seen an example of even internationally, I’ve not seen much reason to believe they’re going to be able to leach into the water.
The permitting through the New York State Department of Health took over a year to review, and it was not an easy review. At the end of it, we felt very confident that this project would be safe. We serve Cohoes and residents of neighboring communities, so we have pretty strenuous water quality tests that will tell us if we need to revisit that analysis.
Could you walk us through what entities will manage what aspects of generation, transmission, and distribution?
In terms of generation, this is a totally municipally-owned array. We’ll most likely enter into a contract with a company to do yearly maintenance checks but this is our asset. For transmission, the solar array connects into a new National Grid pole that connects into their main line, so we have a very clear delineation between where we’re generating and where National Grid picks up the transmission. For distribution, we are going to be on a remote net metering system, so it’s essentially an accounting exercise with National Grid. National Grid still owns the transmission lines, so that’s their deal.
In a lot of the public-facing materials, you emphasize that this is a city-owned project and installation. What made you decide to go that way?
This goes back to 2020. We had a lot of energy service companies asking us about streetlights and solar, streetlights and solar. We were very cautious about the streetlights, and rightfully so - companies typically try to enter into a power purchase agreement with you where they’ll say: “you’ll see a 4% increase in energy costs and 3% increase in service costs, and when you add all that up over 20 years, that’s your savings. So we want to take those savings and use them to build a nice, big project for you.” In other words, “we’re guessing what you’re going to save over 20 years, because no one’s ever seen those increases year over year, and then we’re going to bond money for you and charge you a fee on that bond to make some money now for ourselves.”
There was originally a perception that we were naïve enough to think that we could even build a floating solar array, let alone own one. Ultimately, we didn’t feel that the full life cycle benefits of this array would come to the municipality through a public-private partnership. Around 2020, federal and state incentives also started to change in ways that made it easier for municipalities to own their infrastructure.
TIMBER pays close attention to a handful of state and federal grants for local governments, and there is definitely a structural preference for public-private partnerships. Can you talk about what you’ve seen there?
New York State has a very ambitious goal to reach 70% renewables by 2030. From New York State’s point of view, it would be very hard to incentivize municipalities to get to that 70% by 2030 on such a quick turnaround because of how procurement works, so you want to incentivize the private sector to lead the way. The problem was that the public wasn’t given much to follow because tax incentives overwhelmingly and almost exclusively favored private projects. That made a lot of sense at the start, but it can be a little predatory if we don’t have a clear goal and limited options.
What agencies did you have to work with to get this project moving?
The only state entities we had to work with were the Department of Health (DOH) and the Department of Environmental Conservation (DEC). DOH was because we were modifying a drinking water source, and DEC was because we were modifying a dam. We did work with NYSERDA very early on to identify incentives and lean onto their expertise around solar development. The NY-Sun program has been very valuable for us as a partner.
Have you thought at all about selling the leftover 40% of electricity to residents?
We have. We chose not to because we aren’t yet equipped to have those kinds of contracts and we can’t offer them to everyone, so we’d be picking winners and losers. We also wanted to have the broadest possible impact for this array, and we felt that sharing the array with the school district can impact the tax base on a broader level than signing up 1620 households or so. That might change, but that’s what we’re doing now.
For building and maintaining renewable energy projects, what’s your perspective on how municipalities in the region might work together?
Street lighting is an example of something that might make sense. We’re all taking on our own streetlights. I wonder whether there is a way for us to share technicians and trucks through one entity that’s going around doing maintenance rather than all of us figuring it out for ourselves. Energy is a little weird, because there’s probably not enough space in any of our collective municipalities to generate 100% of our needs for each of us. The low-hanging fruit is probably finding ways to cut down on costs together.
We are grateful that Joe and Tess took the time to sit with us. They have been great partners over the last few years. You can watch a DeepPower video interview with Joe about the project on YouTube.
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