Planning for Ground-Mounted Solar
Hey everyone, I’m in the process of planning for our new construction build in central Massachusetts. We’re aiming for a pretty good house with all electric HVAC. We have good southern exposure and a large lot and I’m considering ground mount PV (~10KW array). I prefer ground mount as I hate the thought of all those holes in my roof, and also for easier replacement of the roof in the years to come.
I’ve talked to a couple of local PV salespeople (including one at a kiosk in Home Depot), and they’ve been fairly useless. They won’t help me until I’ve got the house built and can provide them with a copy of a bill…odd but whatever. Ideally I’d do the PV install while building so I can have post holes and a conduit trench dug simultaneously.
So I was hoping to get some feedback on those who have done ground-mount PV in Massachusetts. Any recommendations for companies? Has anyone utilized one of those DIY kits? Estimated costs? Incentives? Any feedback would be extremely appreciated.
Thanks!
Isaiah
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Replies
Sinclair Skyrack is one local to me in Michigan, they seem to have a pretty good and relatively affordable ground mount setup. 20 panel ground mount is around $3000 I believe. Maybe you can contact them for local installers?
That looks really good, just three steel posts set in concrete. The big costs are going to be a trench between the solar array and the house and the holes for the posts.
You want to keep that trench as short as possible, both to keep costs down and to prevent electrical losses.
You can actually just drive them into the ground, no concrete needed. You need a machine for that, but it's quick if your installer has one. You can DIY them with concrete though too, not unreasonable.
I like the simplicity of it. Definitely worth looking into. Thanks!
The reason they want to see the bill is that you're going to want to do net metering and in order to do net metering you can't install a system larger than the existing usage would require. There's probably some rules your local utility uses to calculate size based on your approved drawings, you may want to contact them and ask.
I recently went through something similar with a new house build. We didn't install the solar until after the certificate of occupancy had been issued. The reason is the Residential Clean Energy Credit only applies to your residence and it's just easier that way. There may be credits for homebuilders.
I recently installed a system in Rhode Island and had a good experience with Sol Power, https://solpowersolar.com/ . They work in Rhode Island and Massachusetts. In particular they are very knowledgeable about the regulatory climate.
That makes sense. It was just a bit frustrating when they wouldn't even give me a ball park estimate. Like, are we talking 15k? 30k?.. but nothing to even get me started.
I appreciate the recommendation. I'll look into Sol Power. Thanks!
$3-4 per watt ballpark, before incentives.
Yep.
There's kind of a gold rush going on in solar right now, between state and federal incentives and net metering it's a really good deal for the purchaser. So a lot of the installers only want to deal with the easiest customers. If you have an existing house with a usage history, and relatively modern wiring it's pretty cookie-cutter for the installer, a lot of companies don't want to mess with anything else.
You'll probably need a remotely triggered disconnect to shut down the solar system, since it will be remote from your home. You'll need to include that in your system design.
I would recommend running at least two PVC or HDPE conduits between the house and the solar system too. Size one conduit for the power conductors, and the other for communications wire for telemetry and control cabling. I would go with AT LEAST 3/4" for each, probably 1". The cost is all in the trenching, so it's best to put in some extra for future proofing so that you never have to go back and dig things up again. Be sure to run cable for a power outlet out at the bottom of the solar install too, to run tools. You can run those wires in a 1/2" conduit since it will likely be required to be kept seperate from the solar power cable, and it must (per code) be kept seperate from the low voltage control cabling.
I'd also be careful with grounding and protection, since solar systems can pick up quite a charge from nearby lightning strikes.
Bill
Isaiah,
Consider killing two birds with one stone, and mounting the panels as part of a covered outdoor space.
https://www.greenbuildingadvisor.com/article/timber-framed-solar-canopies
I like this, and more importantly my wife likes it. This will likely be the route we take. It may end up as a carport as we will not be building a garage. It may also shade a patio or similar.
+1 On this over ground mount.
I build a 10kW ground mount at the cottage and if I could do it again, I would build it into a structure. Something like a partial pole barn with a shed roof using standing seam roof so I can direct mount the panels with clips. The car port above is definitely nice.
No matter how you do it 10kW array is physically large, so try to get it to blend with the surroundings.
Where it gets a little tricky is that a structure that serves other purposes may not qualify for the tax credit. Here's the IRS statement:
(From https://www.irs.gov/instructions/i5695 )
Qualified solar electric property costs are costs for property that uses solar energy to generate electricity for use in your home located in the United States. No costs relating to a solar panel or other property installed as a roof (or portion thereof) will fail to qualify solely because the property constitutes a structural component of the structure on which it is installed. Some solar roofing tiles and solar roofing shingles serve the function of both traditional roofing and solar electric collectors, and thus serve functions of both solar electric generation and structural support. These solar roofing tiles and solar roofing shingles can qualify for the credit. This is in contrast to structural components such as a roof's decking or rafters that serve only a roofing or structural function and thus do not qualify for the credit.
It's not terribly clear, but my interpretation is if you build a carport, and put solar panels on it, the cost of the carport is not eligible. However, if you build a structure solely to hold solar panels the cost is.
Since the tax credit is so hefty -- 30% -- at every step of the process you want to make sure that what you're doing qualifies. This affects your calculus of what to do, when to do it, and who does it. In particular, it may not be worth doing things yourself if it limits the tax credit.
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I'm in solar finance, and I've never heard of a resi solar canopy. Doesn't mean it can't be done, but if you're doing it yourself prepare for some questions from the utility and your permitting team.
david_solar,
What is a resi solar canopy?
Sorry, resi = residential solar, as opposed to commercial or utility-scale solar. Solar canopy is the name given to parking structures that incorporate solar; if you're in New England they're getting more common at places like grocery stores and corporate parking lots, as they reduce the costs of dealing with snow and make electric car charging slightly more affordable.
I wasn't aware that people were putting solar on things aside from roofs or ground mounts on the resi side, at least in any significant way. I know some people build gazebos with a panel or two on top, but it's generally not cost effective to do so.
If you're a homeowner with a workable roof, rooftop solar is the way to go. If you're a homeowner with a ton of land...rooftop solar is still the way to go, generally. A rooftop is a great place for placing panels since the roof is already designed to support a bunch of weight, whereas ground mount solar requires a bunch of concrete and steel, and, if you're doing it by the book, environmental/soil/wetland surveys.
david_solar,
I think the idea is just beginning to spill over into residential from commercial applications.
I mostly agree when it is a binary choice between roof top and ground mount, but to me that choice is really a trade off as to which has the least disadvantages, both practical and aesthetic.
That's why I like the idea of having the panels do double duty creating covered outdoor space, which is beneficial in almost every climate zone.
You should be able to built the structure for close to what a ground mount would cost, and the approval process - environmental, etc - is no different than if you wanted to build a shed or other small outbuilding.
Rooftop solar isn't an option for me, since my roof is oriented such that the ridge runs roughly North-South, meaning the solar panels would be facing east or west -- very much less than optimal!
Ground mount is easy for me, since I have a good amount of acreage here. I'm thinking about building a sort of solar greenhouse design, with solar panels along the back portion that would normally just be insulated roof over the rear work area of the greenhouse. You can put the solar panels on anything that will hold them up, it doesn't have to be the roof of your house.
Bill
Bill, have you had anyone run an analysis on your roof for you? There's basically two software suites that all the solar installers in the US use, and they use satellite photos and complex irradience and soiling models to estimate your production in about 60 seconds. Any decent installer will also come to your property with tools to make measurements on site; you might be surprised at what you can produce regardless of the direction of the roof.
Not trying to talk you out of fixed ground mount, just making sure you're not writing off a cheaper option without cause.
Being in Michigan, the one thing I also like about a lower ground mount is accessibility to clean the snow off it. You can still get decent production in the winter with panels, especially in snowy weather. This makes a bigger difference as Net metering becomes less and less of an option. And the utilities don't make the options that are available very easy either.
With that said, what I am exploring for our house build is similar to what is proposed by the above. Post frame 12x16 or similar structure with a shed roof, enough to fit around 5-6kw of panels. Maybe expansion in the future with the Sinclair system I posted. I'd think the structure (posts and rafters that support the panels) could qualify for the exemption. Sheathing, roofing, floor, probably not.
Noone prevents you to do the trench during the build and the PV with all permits in place afterwards?!?
I agree that I can trench and lay conduits without a full plan. I'd just really like to have an understanding of costs, restrictions, etc. prior to doing that. The cost (and other unknowns) will impact sizing, which may impact location/ number of footings. I really hate not knowing everything up front, so I figured I'd get some feedback from people well ahead of time, rather than just figuring it out after the fact.
There are three limits to what you can do:
* What your local regulations will allow
* What the IRS will allow for the tax credit
* What you can get a contractor to agree to do
An experienced solar installer is going to be well-versed on what the IRS and local authorities want to see. I'd start with them.
I should also have added the local utility to the list. An experienced installer will know what they want too.
Yeah, definitely don't do anything without talking to your utility. Unless it's a fully off-the-grid system, they need to approve your design and interconnection plan. If you're really unlucky, you might be on the hook for transmission upgrade costs as well.
You mentioned that you spoke to some salespeople and walked away unimpressed - who did you reach out to? I'm in Western MA and I'm in commercial solar finance - I don't work for a developer / EPC - and EPCs definitely operate on a spectrum.
For anyone looking for resi solar, I recommend checking here - https://www.amicussolar.com/
The Amicus Solar collective is a group of developer/EPCs across the country who are committed to things people here at GBA probably care about: taking care of their employees (lots of these places are unionized and/or EEOs), taking care of the planet, and doing high-quality installs.
I know there's a few companies in Amicus that do installs in MA - I would reach out to them before committing to doing this yourself. Good luck!
EDIT: Wanted to clarify that I don't work for Amicus or any company that's a member of Amicus; nor do I have a financial stake in any of them. They're just a good group of people I always recommend to homeowners looking for solar and who don't just want the lowest common denominator installer.