I don't know the details of how bitcoin fits in here, but thet say it uses LN in some way now.

For off-grid solar in the developing world there is "pay-as-you-go" (PAYG) models where you can pay a fraction of the purchase amount upfront and then installments while using the solar that your panels produce, until you have paid off the contract (e.g., for two years). If payments aren't made and a grace period passes, then a code is sent via GSM to the smartbox/controller and the panel stops working.

This Melanin solar seems to have pivoted a bit but their initial aim was to do something along these lines from what I can tell -- sell a solar panel and smartbox, and use a utility token that got created from a bitcoin fork that changed the mining algo to an ASIC-resistant one called "YesPower" (for ARM CPUs). (It used a 2019 snapshot of bitcoin, so all who had unspent UTXOs prior to the snapshot were "airdropped" the token ($WHIVE)). So the token buyers were to be those who bought the token to then make the installment payments. This was to run entirely on this Whive blockchain. So I think the smartbox was running as a node on WHIVE blocckain, possibly

https://www.accesswire.com/662987/Distributed-Energy-System-Built-on-the-Bitcoin-Lightning-Network-BLN-and-Whive-Protocol-Piloted-in-East-Africa https://whive.io

Now I see marketing showing that it uses LN.

I'm not sure what they are doing with it nowadays though. And they now have some NFT project that uses the WHIVE token. https://nyukia.com

So I have no idea what ultimately they are doing at this time. But I wanted to share because this pay-as-you-go concept is interesting, and it could be done with Lightning only just as well.