Burning on grape wine is normal, you will find it also in more temperate regions, so in future the outer leaves could act as shading, in case of extreme weather.
On small plants, burning is never a good thing, so I would add some shadows, also just some temporary screens. Forget about the "7 hour sun". I have seen many vineyards which cannot get so much sun (white fruit wine likes colder place). Eventually such rule is to produce some type of wine, in any case such rule should not be applied for such small plants. So a temporary shadow screen is in my opinion needed, and it helps also to have more distances between nodes, so you can get a better vine, with less pruning (this is important on lower part of trunk).
In any case, you planted the grape vine very near each other. I would move them apart (maybe on winter, do not worry, they will growth roots). 50cm is the minimum, but I would put 1 or 2 meter apart, or it will be a nightmare on pruning.
I cannot recognize the variety, but it seems that they are not grafted. In many wine regions it is forbidden to have non grafted grape wines (but on few strict condition, this is done not to risk all wine production). You have not a sandy soil so please consider the risk.
In any case, I do not like your grape vines: they seems too thin and too "zigzag". You should take a more central shoot. [Grape vines will root incredibly well, maybe shorter if you cannot find long shots, but a straight branch]. Also the leaves seem not so healthy (maybe it is just the variety): usually it is because lack of nutrients. If there was previously a lawn, lack of boron is a common cause (and it could be confused with other nutrient deficiencies), so I would just add (when you have enough water) some complete fertilizer with boron.