Haven't tested it recently but when they game came out and xur sold sun breakers every week I tested the damage. The solar grenades only dps so much before they stop doing damage. My testing showed that sunbreakers or not, they did the same damage. Grenades would stay in place longer allowing you to block of areas and if a new enemy went through the grenade it damages them too. If this isn't the case anymore I need to revisit these gauntlets.