Despite not being its primary goal, I will discuss the capability of DUNE as solar neutrino detector. With an exposure of 100 kton-year, DUNE could detect 10^5 solar neutrino signal events above 5 MeV. Separate precision measurements of neutrino-mixing parameters and the 8B flux could be made using two detection channels (charged current on argon and elastic scattering on electrons). The day-night effect can be measured at ~10sigma. These measurements will shed light and eventually solve the long standing discrepancy in the solar mass difference between solar neutrinos and reactor neutrinos (KamLAND). New astrophysics may also be revealed through the most precise measurement of the 8B flux (to 2.5%) and the first detection of the hep flux (to 11%). Significant but realistic new efforts, both theoretical and experimental, would be required to achieve such physics goals.