Reading the article, I believe the number was nearly 2% of Houses of Worship have solar systems and at first glance that seemed kind of low.

Thinking about it more, the number kind of says nothing. Or at least you can't draw any conclusions without a lot more information.

For example, just taking into account a radius of about 2 miles from my home there are 4 churches. All are very old, one is a historic site, none have property (other than maybe a graveyard, but I suspect there'd be complaints) or buildings that would be great for solar (several of the older even have tree issues to contend with). Extend that out and you get two Mega Churches -- one took over a large movie theatre, one was purpose-built as an auditorium with a roof slanted in a manner that might work out well given the position of the sun in our latitude.

The picture they show is of a rural (likely protestant church) -- I suspect these present optimal circumstances, as well, in northern latitudes if they're placed appropriately[0]. It also looks like that's a shiny new roof on that part of the building (possibly an add-on designed to the aesthetic of the adjoining building which will likely get turned into a chapel/event space). Off-hand, I can picture at least two churches in the thumb that have wind turbines on their property[1]. Parts of the thumb are positively amazing from a wind perspective (water on both sides, frequently farms in-between)[2].

I suspect 99% of the reasoning is economical. Churches are complicated beasts. The economics include all of the same lopsided reasons that businesses choose these things along with the weird things churches operating as charities face, like large grants for specific purposes (affecting smaller churches differently than larger[3]). It wouldn't surprise me much if part or whole solar installations aren't being donated in some cases.

If the business provider attends that church, they probably already have a small informal (or sometimes formal) list of businesses they use "because they're honest Christian places." Before the protesting begins about "Honest Christians", it's really more about "This person attends my church implying his personal and professional reputation would be affected if he ripped me off." And if your donation wasn't intentionally anonymous, it'll come with plenty of gratitude from the pulpit and a bronze plaque "or whatever non-tacky thing you want to donate, and maintain, too" indicating that the solar installation was donated by "SunCo" or whatever.

It's an interesting captive audience[4] who is hyper-loyal if you treat them well (for mechanics in my area, it's a ripe market). You tend to get forgiving customers, too. Sometimes repairs go wrong -- I'd jump to "crook", before, and never return. "Seriously, I'm two miles down the road and it's doing it again" ... yes, it's happened with my new mechanic, too. Sometimes a new part causes a failing part to fail and it's not always within the few miles of QA they do after a repair.

But now I just take my car back and "it gets fixed right" (and usually lasts longer than the previous installation).

Back to the hypothetical solar installation. In any market where solar is reasonably hot, if I'm "seriously thinking about solar" but haven't picked a company yet, they shot to the top of my list if they are somewhere near competitive on price. And in the imagined voice of my Mom a decade ago: "They put these solar panels up on our church, but they're not those stupid pink-gold ones, they look really nice!"

... my grand-mother would have complained that they didn't put a Jesus in the middle of the solar cross, or something "Blasphemy!" about it, but every generation evolves.

And some Houses of Worship outright advocate environmental causes. My understanding (from people I used to associate with who were members) of the LDS church is that they encourage various forms of environmentally sound behavior (conservation to the point of canning ... the only 20-year-old bachelor I knew who 'canned'), planting gardens in a sustainable manner. The closest friend of mine who was LDS was the first person I knew with solar panels (really, he had a house with solar panels before many of my peers purchased their first home and he owned it outright in ten years) in our latitude because his goal was to be able to live off the grid and that had something to do with his LDS beliefs (according to him...). I'd imagine you'd have an unusually motivated set of customers.

[0] I don't know anything about solar -- the sun feels like it's directly overhead in the summer, but it at like 70 degrees and 20 degrees in the winter if I'm thinking of the right number and remembering it correctly. I'm not sure what that means for solar positioning, though.

[1] Since this wasn't something I had put much thought to prior to reading this, I am not positive the turbine isn't on the bordering farmland.

[2] There was a map of renewables that had some of the turbines up north -- I know of at least two that aren't on the map as well as a solar installation (both over a decade old but I think the map is pulled from crowd-sourced data/satellite analysis, so I'm not knocking them) but my gut feeling is that there are twice as many as the map indicates. I don't know the economics of it but there must be some money involved to the farmers (and some who feel ripped off) b/c there were some angry road signs.

[3] An accountant at a large church nearby explained to me that there is no point in writing something or another on your check to direct your giving to a particular ministry unless it's a massive amount of money -- they have a set budget per year and if someone gives extra to "Mission Trips", they don't just make the Mission Trip budget bigger -- they balance it against the general fund, so unless you plan to fund the entire category and sprinkle some on top, they'll have the same budget they had last year. And for a large church, they better -- everything is dependent on people; over-funding doesn't make them appear.

[4] My mechanic is well known for handling the cars for everyone who attends (now a handful of local) mega-churches. One year he chose to donate $500 of services to single moms on Mother's Day (fifteen were pre-selected before each service, not a small donation) and if you know the shop, that $500 is $1,000 anywhere else. The first year he did this it took a day to get into his shop. It's been years of him doing that on-and-off, his shop moved to a location four times the size and he still can't keep under a week wait (and I wait, happily -- he's a very honest mechanic that I would not have found outside of that church service).