well i have to retract my statement i belive i just had to much wattage going on in my tent the vipar seems to be doing great i added cal mag to my nutes an the ladys love it fixed my little problems right up as far as heat they give off a little heat yes but haveing the proper ventaltion helps out good .. im only using half of the 600 watt panel at the moment along side the 250 watt hps/t5 light an the girls under the led are really filling out nicely vs the hps as far as veg goes there great haveing had any experince in bloom yet but i plan on running a side by side comparison to see will keep posted but for the money vipars aint bad would recomend for low budget led grows for sure ...