An embodiment includes an apparatus comprising: a first photovoltaic cell; a first through silicon via (TSV) included in the first photovoltaic cell and passing through at least a portion of a doped silicon substrate, the first TSV comprising (a)(i) a first sidewall, which is doped oppositely to the doped silicon substrate, and (a)(ii) a first contact substantially filling the first TSV; and a second TSV included in the first photovoltaic cell and passing through at least another portion of the doped silicon substrate, the second TSV comprising (b)(i) a second sidewall, which comprises the doped silicon substrate, and (b)(ii) a second contact substantially filling the second TSV; wherein the first and second contacts each include a conductive material that is substantially transparent. Other embodiments are described herein.