the typical "industrial" version of powerline is IEEE 1901, which for example is used by some electrical utilities for SCADA and by some smart meters. The difference can be somewhat academic as many modern powerline protocols are members of the same "family," and IEEE 1901 has two different PHYs that are basically adoptions of HomePlug and HD-PLC (another powerline protocol that I didn't mention because it never really went anywhere with consumers). Some HomePlug devices are certified as interoperable with the HomePlug-derived flavor of IEEE 1901, so sometimes they're literally the same thing.
IEEE 1901 is only specified for 500Mbps though. The more industrial use-cases are rarely high-bandwidth and that market is often pretty satisfied with even Kbps performance, they're just sending Modbus and that sort of thing. IEEE 1901 equipment is also going to be quite a bit more expensive to obtain since the market is small and mostly works on large contracts.
I agree with others that point-to-point wireless is probably your best bet. It can be similarly priced to HomePlug AV2 transceivers and, sort of ironically, will probably turn out to be more reliable. HomePlug tends to have trouble when there are neutral bonds because that adds "side legs" to the bus that harbor reflections. That's why people tell you that, as a rule of thumb, your transceivers need to be on the same circuit for good performance. It's a particularly bad with an outbuilding scenario because you've probably got two panels with two neutral buses, adding two different sets of reflections. Hard for the modulation scheme to contend with. I've personally run HomePlug AV1 from a house to a pump shed with a subpanel and got ~15Mbps performance with near-total dropout when the pump was running. ymmv depending on the wiring.
You might also consider direct-burial Ethernet, which is not very expensive. However, you'll get into some complexities with bonding and lightning protection and you might need to study the code book a bit. Some people will insist that one must never connect separate buildings with metallic communications conductors, but I would remind them that until about the 1980s that was the only way to do it, and techniques and equipment to do it safely have been developed. You just have to, you know, learn and use them.
IEEE 1901 is only specified for 500Mbps though. The more industrial use-cases are rarely high-bandwidth and that market is often pretty satisfied with even Kbps performance, they're just sending Modbus and that sort of thing. IEEE 1901 equipment is also going to be quite a bit more expensive to obtain since the market is small and mostly works on large contracts.
I agree with others that point-to-point wireless is probably your best bet. It can be similarly priced to HomePlug AV2 transceivers and, sort of ironically, will probably turn out to be more reliable. HomePlug tends to have trouble when there are neutral bonds because that adds "side legs" to the bus that harbor reflections. That's why people tell you that, as a rule of thumb, your transceivers need to be on the same circuit for good performance. It's a particularly bad with an outbuilding scenario because you've probably got two panels with two neutral buses, adding two different sets of reflections. Hard for the modulation scheme to contend with. I've personally run HomePlug AV1 from a house to a pump shed with a subpanel and got ~15Mbps performance with near-total dropout when the pump was running. ymmv depending on the wiring.
You might also consider direct-burial Ethernet, which is not very expensive. However, you'll get into some complexities with bonding and lightning protection and you might need to study the code book a bit. Some people will insist that one must never connect separate buildings with metallic communications conductors, but I would remind them that until about the 1980s that was the only way to do it, and techniques and equipment to do it safely have been developed. You just have to, you know, learn and use them.