thank you, i figured it out before you posted this... or rather... was figuring it out as you posted this... and still, the reason for the higher cost (solar power) is it's ease / stability and "leave it alone" function... i prefer it, even though it is so much more expensive for the sole purpose that once it's done... i don't have to feed it steam, fuel, oil, compressed air... nothing... it's just there and done. for ore processing off a quarry and to set it as part of a chain to auto gain every ore i need from then on on a throw away world (mystcraft) with a quarry... it's no biggie once you get there and a free for all from there.
http://ftb.gamepedia.com/Battery_Buffer#Batteries lists which of the standard IC2 and GT batteries are which tier for GT - for the GT batteries listed in multiple tiers, small ones are LV, medium ones are MV, and large ones are HV.
There are very few add-ons that provide machines or generators for GT power, so it's generally safest to assume generators that are not from GregTech itself will generate IC2-style power (unless they provide other forms of power, e.g. Thermal Expansion generator will produce RF rather than EU, although I think GT5u has a config option to allow RF as input)
If you have NEI, they should show what mod they're from while they're in your inventory at least, and in the list at the right. You can add the mod called WAILA ("What Am I Looking At") to see what mod blocks placed in the world are from.
The non-3d ones near the end with the 8V, LV, etc. labels in the textures are the GregTech solar panels. I think I once tried putting a solar panel directly on top of a battery buffer and it didn't seem to work, but I've definitely gotten solar panels to work when placed on top of horizontal 4x cables feeding into a battery buffer. You might reconsider using solar panels as your main source of power once you notice that the recipe calls for two circuits for 1 EU/t output, and the recipes for each higher tier solar panel requires enough of the previous tier solar panel to match the output level, unlike steam/gas turbines and diesel generators, which just require higher-tier circuits, motors, etc. rather than multiple lower-tier generators in the recipe.