Module 3: Text Versions
Below are the video text versions for Module 3 of the City and County Solar Photovoltaics Training Program.
Once you've determined a site is favorable for a solar project, a detailed site evaluation will identify potential barriers. Some of the most common obstacles arise around relevant decision makers, solar policy, site plans and usage, technical feasibility, economic factors, land use permitting, and mounting type. Learning how to properly evaluate a site provides for the possibility of successful mitigation strategies plus time and money saved, but may also help lead to the identification of other alternative potential sites.
>> Lars Lisell: Hello. My name is Lars Lisell. I'm an engineer with the National Renewable Energy Laboratory, and today I will be talking about detailed site evaluation, project validation, and permitting. And I am here with my colleague Megan Day, and we're gonna split up this training by – I will start by talking about small systems, and then Megan will talk about larger non-net-metered systems. In this module we'll walk through the key considerations and activities that should be performed when evaluating a site for solar photovoltaics. Everything from collecting information to walking the site to identifying different rooftops that might be available for solar PV, and then also understanding the differences between small systems and large systems, and how that will affect the process by which you do site evaluation. To recap what we have learned so far in the PV project implementation process, module 1 we walked through the different considerations for setting goals and building a tem. Module 2 we looked through some different tools and processes available to identify sites and screen them for feasibility, and now we are on module 3, site evaluation. In this training I will start by talking about some relevant solar policy. Then I will discuss the site evaluation process for small systems, walk through some economic screening tools, and then I will pass it over to Megan to talk about considerations for screening for larger systems.
One of the key policy considerations for a project is whether the project qualifies for net metering or not. So net metering is the ability of a project to push energy out to the grid and be credited for that energy at retail rates. If the project does not qualify for net metering, typically any power that's pushed out to the grid is valued at avoided cost of energy. And the avoided cost of energy is typically substantially less than the retail value of that power. Net metering programs also typically have a size limit, so there is an upper limit on the capacity of a project that can be connected under the program, and a program sometimes will also have a requirement on overproduction, or an upper limit on overproduction that is allowed under the program. So for instance in Colorado you can interconnect a project that will produce up to 120 percent of the facility load and still qualify for the net metering program. Other states have other rules, but it's pretty typical to have an upper bound on system size and system production. There are a couple of good resources that will help you figure out if net metering is available in your location. One is the Fifty States of Solar Annual Review, and another is the Freeing the Grid Annual Summary.
Another key policy consideration for a given location is what sort of interconnection laws exist for that location. Typically each state has different interconnection laws. Each utility has different interconnection laws and guidelines. There will be an upper limit on the size system that can be connected under interconnection rules, and these are typically set by the Public Utilities Commission, so they'll apply to certain utilities. Municipal utilities are sometimes exempt from statewide interconnection laws, but in that case they will have their own interconnection requirements. And if a system is larger than the upper limit that's set for the expedited interconnection process, typically then a study will need to be done that investigates what sort of impacts that system will have on the system, and those studies have a cost associated with them, and they also have a time requirement associated with them. So it's the type of thing where if you are above the size system that can be connected under the expedited interconnection process, it might take a couple of months to do the study. That might push out the timelines on the project a little bit. All good things to know and to understand. Some good resources for interconnection rules: you can go to dsireUSA.org; they typically have a good summary by state. And then also IREC, they release – they have a publication called The Model Interconnection Procedures, which outlines some of the sort of best practices for interconnection laws.
Another piece of policy that can have a substantial impact on site feasibility is sort of if there are any limitations on renewable energy construction or solar PV construction in a given jurisdiction. There are some places around the country who have put moratoriums on building solar PV on farmland, for instance; building PV on historical structures, sometimes there can be limitations there. So kinda spending some time digging in to the limitations that you may interact with for a given jurisdiction is very important to do. And city and state government websites typically have any sort of restrictions summarized. So going to these government websites, looking at what the restrictions are, and then figuring out how that might apply to a potential project is definitely something that's important to do from a policy stand point. There are also solar access laws in some places. If you go to the website solarresourceguide.org, there are good resources available to help you work through these types of projects. In further modules we'll have subject matter experts going through additional policy considerations in more detail, but I wanted to summarize just a couple of policy implications as they relate to site evaluations. So now we'll switch gears and talk more about the technical feasibility side of things. And as I mentioned earlier, I'm gonna talk about small- and medium-scale systems, primarily systems that will be net metered, and then my colleague Megan will speak about larger systems. So generally when you start thinking about site evaluation and kinda moving from conception through system development, you have to think about this topic of assessment in sort of three steps. Step one, assembling information about the site. Step two, collecting information, going out to the site, taking photos, starting to get an idea of how large of a system you may be able to implement. And then step three, where is the power gonna be connected, and what is that configuration gonna look like? Is it a connection that goes right into the building? Is it a connection that goes into a campus grid? How are you gonna land the power, and how is the power from the system gonna be utilized by the facility.
And ultimately as you are walking through the site evaluation process, really what you're looking for is any sort of roadblocks. So are there things on the site that are going to delay or slow down a project. What sorts of issues on the site may sorta derail the project? So it's really about thinking through all of the different characteristics and all of the different site considerations in order to go from project concept through successfully building a project. I've outlined kind of some of the key considerations, key things that should be considered when you're doing a site evaluation, and I will talk about each of these in more detail in further slides. The first specific consideration that I wanted to go through is interconnection point. This is one of the sort of key nuts and bolts considerations for building a project, is where is the project actually going to be connected to the electrical infrastructure, and then how is that power going to be used on site? So depending on if you're doing a roof-mounter or a ground-mounted system, the considerations for interconnection point are gonna be slightly different. For a roof-mounted system, typically that is gonna be connected directly into the building electrical panel, so you have to think about what kinda capacity is in that electrical panel? Is that electrical panel in good functioning order? Is it fairly new? You don't wanna be connecting a large, brand-new PV system into an old electrical panel that's overloaded. So you need to think about things like spare capacity. Also you need to think about how far that interconnection point is from the system itself. So are you gonna have to do a tremendously long wiring run to get from the system to the inverter, and then from the inverter to the electrical panel? Or is it somewhat – is there a convenient space that you can put that? And then also, physically, is there space in the building to site that equipment where it's not gonna get in the way, where it's – you're gonna have sufficient set-back so that it meets electrical code, and everything like that? On the ground-mounted side of things, the considerations are slightly different. Where are you gonna land the power? Is there electrical infrastructure in that location? In a building, typically there's always electrical infrastructure, and there's always gonna be an interconnection point. If you're doing a ground-mounted system, you might have to bring the electrical infrastructure out to the place where the system is physically located. And then, once the infrastructure is out there, and there's a place where you can connect the power, what sort of other infrastructure is required? From an electrical standpoint you might need a transformer, and there could be other electrical components that you need in order to physically make that connection, and make the systems successfully interact. The other thing to think about with the ground-mounted system is who owns the electrical infrastructure where you wanna interconnect? Is it behind the meter, and it's owned by the site, or is it in front of the meter, and it's owned by the utility? So these are all important considerations, and very, very central to the ultimate feasibility of developing on a site.
So there are some simple ways that you can evaluate sort of on the load side, whether a interconnection point is going to be feasible or not. Typically you're connecting into like an electrical panel, or for net-metered systems you'll be dealing with sort of smaller-scale stuff, so you can typically land that power on a building breaker or on some campus infrastructure. So you kinda need to at least take a first pass at deciding is there sufficient capacity within this infrastructure in order to accept the amount of power that the system will be producing. If the panel does not have sufficient capacity, you still have a couple of options. You can survey the loads, and potentially reduce the capacity on some of those breakers. You could potentially upgrade the panel, so just take the panel out and replace it with a new one that has a higher capacity. If you don't wanna replace the panel itself, you could do a line-side tap, that's another option. Or you could potentially upgrade the electrical service, and that's probably the most expensive option, so that would be like the last resort. But all of these are options to consider. And each one of these solutions has a cost implication. The amount of PV that you can fit in a given area is also a key consideration for doing a site evaluation. If you have a certain amount of load at a building and you wanna offset that with a PV system, you need to know how much ground area is gonna be required in order to build a system of that size. Or inversely, if you have a parcel that you're considering for PV, you need to be able to know how much PV can be built in that area. So I've pasted some values for different technologies and different system styles, and then also different mounting options, and the energy density for those different options. And those numbers can be used to calculate how much PV you can fit in a given area. And the reason that there are differences between these technologies is because of the nature of how the systems are laid out. So ground mount, you need to have space between the panels for doing maintenance, access for cleaning the panels, et cetera. Roof mounted, you need to have some area for emergencies or first responders, setbacks for fire code, things like that. So you can't physically put panels over every available square foot for a site. There is some area that's not gonna be usable. And that's gonna change depending on what style system is used. And I think we're gonna have a homework question on this, so you'll have an opportunity to run some of these calculations.
The other thing to consider when looking at different types of projects is, how is
that decision going to affect the financial feasibility of the project? So here, what
we have laid out is sort of in the ecosystem of different solar PV solutions, how
do these stack up in terms of cost. Obviously you've got carport on the one extreme,
and then you've got developing greenspace on the other extreme. But as you start working
through a site, and look at sites across your portfolio, it's important to consider
how these cost implications are gonna affect project feasibility. Also when you're
looking across different potential sites for rooftop systems specifically, you need
to consider how long the roof is gonna last, and if there will be a roof replacement
on that facility during the lifetime of the PV system, because that is gonna have
cost implications as well. Ideally, any sort of new PV that's implemented, the roof
would be new and have a 25-year warranty. That's gonna be difficult to do for all
locations, so it's acceptable to implement PV on roofs that have less than a 25-year
warranty or less than 25 years of useful life left. But it needs to be understood
that for those systems, there's gonna be some cost associated with taking the PV down
when that roof ultimately need to be replaced.
And then also just considering the style of roof – If you're gonna put PV on a roof, it's gotta be able to handle the weight, and it shouldn't be kinda like a temporary roof that may go away in the near future. When looking at different sites for rooftop PV, some rooftop sites are going to be much better than other sites. The sorta key considerations for picking a good rooftop space is: Does that rooftop space have a good south sky view? Will you be able to orient the panel due south, or have the azimuth at zero degrees? And also, will you be able to tilt that panel somewhere close to latitude? If you can meet those conditions, you will be able to get the maximum energy production out of that system.
Once sites have been screened for some of the considerations that we talked about in the previous slides, then you wanna start thinking about things like shade. And PV is very sensitive to shade, so typically what we recommend for doing site assessments is removing any areas that have less than 90 percent solar access. If it's a large open field, typically you'll only have to worry about shading on the periphery. If it's a rooftop, you need to worry about things like trees and other buildings that potentially would shade some of the useful area. But once you have a shading assessment and have identified the level of shading, then you can use those numbers to estimate system production; you can estimate system size based on removing the shaded areas; and then run the economic analysis on those locations. When doing a site evaluation, it's easy to get sort of wrapped up in these technical considerations – where you're gonna connect it, if the tilt's gonna be right, things like that. But also make sure to think about the other people who might have information about the site. People that have worked at the organization for a long time and might know of some long-term plan that's been developed but hasn't necessarily been written down. People that might know about things that happened on the site in the past, so if there are gas tanks or something like that buried on the site that someone else might not have any knowledge of. And just make sure to socialize this idea, and talk with as many people as possible. There's very rarely any harm in having too much input when you're screening a site from different members of the team, so it's very important to also consider who's gonna be contributing information, and also just kind of socialize that idea as much as possible. Also it's important to get early buy-in from decision makers. That way, if you do run into little problems, or have little speed-bumps, it's not gonna derail the entire project. You can still continue to move forward and develop a site and create a successful PV project.
So once the technical considerations have been evaluated when you're looking at a site, it's also really important to do at least a first pass at economic feasibility. And this isn't a detailed cash flow or a really in-depth analysis of what the system economics are gonna look like, but just kind of a very high level, "Does it look like the numbers are gonna work?" type of analysis. There are several different tools available to help run this sort of high-level economic analysis. Kinda going from least complexity to highest complexity on the kinda fast and quick side of things, PV watts is a good screening tool. You can do an analysis in just a few minutes, but it'll give you really good numbers. It's a very useful tool for doing kinda this first pass at economic evaluation. In module 2, we learned about the second tool I have listed here, REopt Lite. REopt Lite takes a few more inputs and likely will be a little bit – there'll be a little bit more of a time commitment to collect all the information that you need to run REopt Lite, but as we saw in module 2, it's a very user-friendly tool and can help you with things like sizing as well. So that's kind of a medium-level-of-difficulty tool that you can use. And then, on the detailed side, the system advisor model, you have the ability to a very, very detailed analysis. There are some ways that you can do kind of a quick screening analysis, but you can also get very much into the weeds and run something that's very detailed. But any of these three tools would be applicable for doing a site-evaluation-level economic analysis.
Another way to perform a high-level economic analysis for a site is to leverage map tools, and there are a number of different tools available at this point. There are nationwide tools; there are local tools; there's a lot of resources, and a lot of different ways that you can leverage those to perform a high-level economic analysis. Project Sunroof is one that I think has been mentioned in previous modules. That's a good tool. There are local tools available for City of Cambridge. New York City has a solar map – it's actually New York City and New York State. Cooke County in Illinois has a local map, and there are other tools as well. The nice thing about the local map tools is they typically take into account location-specific considerations – things like local solar resource, local incentives that might be available from a municipality or a utility, and just really detailed information for a given location. Whereas some of the nationwide tools might miss some of those more nuanced incentives or very detailed local information. The last way to start to get an idea of whether a project might be feasible in your location, or at a specific site, is to research other projects that may have been successfully completed nearby. If you're looking at a municipal project, you might look at other municipalities that have had success with PV. If you're a school district, it might be a school project. Or if it's a large sort of municipal infrastructure project, something like that, you might check with other municipalities that've been successful, or city agencies that have been successful implementing PV projects. And there's a wealth of information that you can get from someone who has successfully been through the process. What slowdowns were there? What policies were difficult? There's a lot of information that can be gleaned from somebody who's been through the process, who's kind of navigated the waters, and I would definitely encourage some sort of review of projects that have happened in the same sort of jurisdiction or geographical location. And with that, I will turn it over to my colleague, Megan.
>> Megan Day: Hi, this is Megan Day, a renewable energy planner at the National Renewable Energy Lab. And now we're gonna take a look at non-net-metered, ground-mounted PV sites, and site screening considerations specific to those projects. There are many siting considerations unique to larger ground-mounted PV systems. Ground mounted systems generally require between five and ten acres for each megawatt of installed capacity. Single-access tracking systems require slightly more land than fixed, south-facing systems. And site constraints can seriously increase this acreage required. PV arrays are about six to ten feet high, and larger facilities may have an on-site storage building that can be about 12 to 20 feet high. You also have inverters and transformers that'll be between six and ten feet high, if they're not enclosed, and a little bit higher if they do have an enclosure. In a single-access tracking system, the arrays are aligned on a north-south axis to allow modules to face east as the sun rises and track the sun to the west over the course of the day. Tracking systems have higher capital costs, and operation and maintenance costs, but they can also increase generation by about 20 percent, and so therefore they lower the overall cost of the electricity generated. Tracking systems also require more grading than fixed systems, as they require more uniform slopes. Fixed-tilt systems can accommodate more rolling or undulating topography, so that's something to consider when you're looking at your site. A security fence is required for safety and will generally be about six feet tall, chain link, with an additional foot of barbed wire or razor wire. You can require decorative fencing or a landscape buffer, but this will increase the cost of the facility and the associated solar energy generated.
When you're considering your siting, it's important to understand that solar farms, while they might look very intense land-use-wise from the air, folks on the ground will only be looking at the fence and the first row of modules, as you see here. Proximity to interconnection is a key siting consideration. An ideal location for a multi-megawatt facility is right next to a substation. The size of the facility is relevant when considering interconnection points. If you look out and you see high-voltage transmission lines, this does not necessarily mean that it's a good place to interconnect, for example, your one megawatt community solar facility. So if you look at the schematic on this slide, you'll see that there are of course different voltages associated with transmission lines, subtransmission and distribution lines. So for example that one megawatt solar facility could interconnect at the distribution voltage at a substation or a line tap into the 13,200 volts or 13.2 kV. If you have a larger facility, say a 20 megawatt facility, that can absorb the costs of the associated equipment. These little boxes there are the transformers that are pretty expensive pieces of equipment. So a 20 megawatt might be able to absorb the cost of the transformer to step up the voltage from a 20 megawatt internal voltage of probably 1,000 volts to the 69 kV here at subtransmission. In order to connect at transmission voltage of 345 kV or 500 kV, you need something more like a 100 megawatt facility to absorb the costs of the associated step-up transformer to go from an internal voltage of 1,000 or 1,500 volts that you'll find on your PV facility to the 345,000 or 500,000 volts on transmission-level lines. Also you wanna consider the capacity of those lines. SO just because there might be an appropriately-sized transmission or distribution line next to your facility, it doesn't necessarily mean that there's capacity on those lines in order to feed your electricity onto that system. That's something that your utility will know, the utility that owns those lines.
Next we'll take a look at some specifics related to ground-mounted site screening. Specific considerations for ground-mounted and first steps to take when you're looking at a site include: exploring the site on Google Earth; diving into take a close look, going on a street view; looking at topography maps to understand the slopes and any kind of site constraints, find out the zoning; and very important is to walk the site. And when you're out on the site, you wanna make sure you're looking for things like, maybe there might be some tall trees to the south, or buildings to the south, that could shade the site. Look at rivulets, or water flowing over the site, or evidence thereof, to understand if there's water flowing from an adjacent property that might have to be dealt with. You wanna look for flat areas, site constraints, proximity to interconnection, access to the site from driveways, and shading. Ground-mounted site screening criteria include things like: Are there wetlands, water bodies, washes, arroyos, or drainage considerations, or a flood plain on the site? I've included here two resources, the Fish and Wildlife Service wetlands mapper as well as FEMA's floodplain mapping, so you can screen for these kinds of site constraints. Another condition is the soil conditions, and these can impact the structural design and site feasibility. So for example if there's caliche or bedrock on a site, that could require some very costly drilling to drill your racking into rock. Sandy soils might require deeper post embedment to meet wind and snow loading requirements. And corrosive soils can require the posts for your racking to be treated, and that adds cost and time. So here I've included the web soil survey as a resource to have a preliminary screening to understand the soil and understand if there's any red flags. Also you wanna look for critical habitat, riparian areas, and endangered species of flora or fauna that might be impacted at the site. Here you've got the Fish and Wildlife Service critical habitat mapper as a resource to understand a cursory desktop review, to see if that might be a consideration.
Driveway access is critical. Is this site requiring a new driveway? If so, maybe you're on a limited-access highway that might not allow a driveway at that site, so that might be a site constraint. Also you wanna look at can equipment and materials be safely delivered to the site, with no obstructions like overhead utilities, trees, or vehicle weight limits on the access roads. So here you wanna check your state and federal department of transportation for those considerations. Easements, encumbrances, and rights of way can be major impediments to your site. It's important to look at things like the USGS topo map, and I would encourage you to pull up – there's a link here – and look at both the new topo maps, with the pretty overhead satellite images, but also look at the old versions, which can show abandoned pipelines and historical site constraints that may still impact your property. Also you wanna look at, are there utility easements or railroads that will have to be crossed, either at your site or by an interconnection line? And then you also wanna look at the local plans for transportation. So for example if the adjacent roadway is planned to be expanded in the next 25 to 40 years, the life of your project, you may be looking at for example a 200-foot setback versus a 50-foot setback, and that could impact the capacity that you can build on your site. Cultural, agricultural and visual resources are also important to look at and understand – if you have cultural resources on the site, or if there might be agricultural protections or conservation easements, and whether the site might be within a sensitive viewshed. So the resource here is the National Register of Historic Places, which has historic preservation sites. But there's a lot of sites that are not gonna be on that mapped resource, so you need to work with your state historic preservation office, and perhaps do a cultural resource study at the site to understand the details and the constraints there. It's very important to look at the land use and the zoning of your facility. What kind of zoning district is the property in? Because there are setbacks, height restrictions, allowances and exemptions that may be applicable to a solar facility, or any kind of building, on that zoning district in general. You may want to look at if there are rights-of-way permits, including for your interconnection line, driveway or drainage, and then what kind of building permits are required. So here you wanna go to your city or county zoning map, or your state and local building code requirements. Also you wanna look at storm water and drainage issues. The impervious surface considerations for solar panels in your jurisdiction will impact how much you might have to build for retention ponds or swales for erosion and sediment control. And so if for example you have to build major retention ponds on your site, that's gonna impact the available land for your system capacity. And of course if your site is an acre or more, you're going to need a construction storm water permit.
Now we'll look at ground-mounted permitting screening requirements. Different types of permitting are of course required. Interconnection agreements will always be required. Environmental permitting may be, given the considerations we just discussed. Transmission permitting might be required if you have an additional interconnection line that needs to be built. Offtake agreements you'll always need. Local permitting coordination is always required, unless you are above the threshold and your state is the one that has authority over the siting of your facility. So of course state permitting can sometimes be required, even for wetlands or siting, and then federal permitting may be required, and that could include NEPA. Here I've included a rough checklist of some permits that may or may not be required for your perusal. I won't go through all of them, but it lists different federal, state, and county, city, and local permits that may be required. And the federal one to really look out for is NEPA, that's the National Environmental Policy Act. And that will only come into play if there's a federal nexus of some sort – Are you requiring a federal permit? Are you using federal land? Are you interconnecting to WAPA? – and those considerations. Most local projects will not require a NEPA permitting process, which will save you lots of time and money. It's important to consider your neighboring land uses and landowners, and accommodate community outreach and education to help them understand the potential project that you're considering at that site. Addressing community concerns can help you avoid NIMBY-ism and local opponents to your project. Some common community concerns include whether the system might cause glare, or blinding, or dazzling. And actually, solar modules are less reflective than water and windows, so they're compatible with nearby residential office or aviation uses. Solar facilities that are ground mounted and larger scale have very low noise. The inverters do make a hum which sounds something like a refrigerator when you're standing about ten meters away. So outside the fence line it's really not a concern. A tracking facility will make a slight whirr as the facility moves the modules over the course of the day, but again, outside the fence line it's really less than ambient noise. These facilities are safe, modules are warrantied and enclosed in glass, and they're low voltage. So some people have electromagnetic field considerations and concerns, but actually the voltage of a larger solar facility is far less than the transmission and distribution lines that we looked at previously. Down below is a blog that talks about some of these large-scale solar myths and how to address them.
If you're issuing an RFP for a ground-mounted solar facility, you may want to consider requiring certain kinds of revegetation standards. One option is to require pollinator-friendly vegetation on the solar facility, and some examples here include state policy in Minnesota and Maryland, where they've established pollinator-friendly solar standards. And in Linn County and Stearns County, where they've established local policy for solar farms requiring pollinator-friendly revegetation techniques. Even if you don't require pollinator-friendly vegetation, you might want to require something like a native species revegetation seeding mix, and that can help with soil stabilization and erosion control and sedimentation control. Here are some further resources to help you with your site evaluation. Local solar resources include, as Lars mentioned, the Google Project Sunroof site, where they also have a data explorer, where you can look at the solar potential for generation and for area on rooftops throughout your entire community. There's also the state and local energy data site, where you can look at things like your utility rates, as well as things like the small building rooftop PV potential for your community. Another resource that I would encourage communities to take advantage of is the SolSmart program, which is a designation and technical assistance programs for cities and counties throughout the US. It's important for siting, because you can receive free technical assistance from the SolSmart Project as a participant on siting as well as permitting inspection and things like planning and zoning for solar in your community.
In conclusion, rigorous site evaluation and data collection up front can help you save time and money during implementation of your project. Technical solutions can overcome many barriers that you might identify through this process. And with proper screening, most issues can be identified and mitigated. And we encourage you to dig deep – talk to everyone who has knowledge of the site to uncover any complicating factors and ensure project success.
I'm Otto VanGeet, I'm an engineer here at the National Renewable Energy Lab and I've been here for 27 years and I've been involved with numerous PV projects here on our campus.
When you start the selection process, you should figure out what the load is that you are trying to meet. If you're trying to meet an on-site load, you want to get a year of utility bills, figure out what your utility rate structure is, figure out your electrical interconnection requirements - Is there net metering? Is there incentives? Those sorts of things.
Then the next step in the process is, once you select the sites, to figure out possible electrical interconnection points and constraints.
So, we've considered dozens of sites here on our campus, it's about a 300-acre campus. We've considered ground-mount, roof-mount, and carports. For the ground-mount sites, one of them we considered actually was the one in the background here. Great site...nice and flat...good utility interconnection...but it turns out we have future plans for that site.
So what we settled on was a large ground-mounted site on our mesa top that was previously
disturbed. And we put in about 3/4 of a megawatt of single-axis tracking on that site.
Single-axis tracking requires very flat land, so they had to come and do some grading as you can see for the land.
The one constraint we had on this site is that there's an existing 50-foot wide easement for a natural gas line that we had to work around. When we went out to bid with that, we had the site plans drawn, including the 50-foot easement.
When considering sites, bigger is better. The lowest cost solar will always be the largest, flattest, easy-to-interconnect piece of land, but again you gotta make sure there's no future plans for that land. The next lowest cost will be large, flat open rooftops and the most expensive will be PV carports, because of the structure required for the PV carports.