...With such a road you dont need heating elements. The power circuits will produce heat which will be consistent, good to melt snow so just by using the heat from energy loss in making electricity you save even more power instead of using energy for a heating element.
You have a huge underestimation of the efficiency power circuits reached in these years, and a bad understanding of the amount of joules you need to melt snow.
And combined: How to melt snow on panels with the unefficiency of circuits that convert no energy because the panels are under that snow?
While snow requires a lot of energy there is one other factor, time. You can melt snow using a low heat output but it will take longer. All those power distribution, power converters and all other components they produce heat so why be wasteful. Think about it this way, this system will be running the whole time, LEDs and power still distributed at night. Snow doesnt come down as 1 big lump, it comes down as flakes. Its only in places that get really really bad snow like the far north where the snowstorm is so thick that you cant see a thing and you get snow coming down onto the road from the slope next to it that you would need heating elements.
I'm not sure if you're from the UK or north Idaho, but your 100-level physics needs some remediation.
There is no "discount" for melting snow on an installment plan. Also, the thermal losses from the balance of plant equipment are quite small. The prototype system for Solar Roadways uses Enphase micro inverters, which are 96.5% efficient, which means that 3.5% of the input energy is dissipated as heat. For a 250W panel running at full output (which a panel in a solar road will NEVER achieve), 8.75W will be dissipated as heat. In a snowstorm even in daylight, that 8.75W will likely be 1-2W - for a very brief time until the road is covered with snow or brown filth, which is the usual state of the roads when snow melts.
A 250W solar panel has a surface area of approximately 1m^2, thus you're looking at 1-2W/m^2. I'm not going to go through all the rest of the calcs, but it is just totally implausible that this low energy density would be remotely near what it would take to melt snow reliably. The sun strikes the earth at 1 kW/m^2, so even in wintertime, we could reasonably expect 100W/m^2 to strike the ground during the day. So, why bother building a solar road, when doing nothing would be 100 times as effective and cost nothing?
The reality is that a snow-melting roadway is an energy *sink* not an energy source. The only way it could possibly work is to pump electricity into the road, and lots of it. Solar roadways are a complete and utter farce that only serves to separate us from our tax dollars.