NOVELTY - Forming an aluminum back electrode of a silicon solar cell (400) comprises: applying a silicon-free aluminum paste composition on p-type silicon substrate, where the paste composition comprises 0.03-9 wt.% of an (a) additive which is calcium oxide, calcium oxalate, calcium carbonate and/or calcium phosphate, (b) 27-89.9 wt.% of an aluminum powder, and (c) 10-70 wt.% of an organic vehicle; applying metal paste on p-type silicon substrate; and firing p-type silicon substrate after applying the aluminum paste at 600-950 degrees C.    USE - The process is useful for forming an aluminum back electrode, that is used in the solar cell (claimed).    ADVANTAGE - The process provides solar cells that exhibit reduction in cell bowing by at least 50% (claimed) without impacting cell efficiency and adhesion.    DETAILED DESCRIPTION - Forming an aluminum back electrode of a silicon solar cell (400) comprises: applying a silicon-free aluminum paste composition on a back-side of a p-type silicon substrate, where the paste composition comprises 0.03-9 wt.% of an (a) additive which is calcium oxide, calcium oxalate, calcium carbonate and/or calcium phosphate, (b) 27-89.9 wt.% of an aluminum powder, so that weight ratio of aluminum powder to (a) is 9.1:1 to 999:1, and (c) 10-70 wt.% of an organic vehicle; applying a metal paste on a front-side of the p-type silicon substrate, where the front-side is opposite to the back-side; and firing the p-type silicon substrate after applying the aluminum paste at a peak temperature of 600-950 degrees C, where the step of firing the additive promotes a growth of silicon particles having an equivalent diameter of 2-15 mu in a particulate layer of the aluminum back electrode. INDEPENDENT CLAIMS are also included for:    (1) the silicon-free aluminum paste composition for forming the aluminum back electrode with large silicon particles; and    (2) the solar cell comprising the aluminum back electrode, where the aluminum back electrode comprises the particulate layer disposed on a eutectic layer (462), the particulate layer comprises silicon particles and the aluminum back electrode comprises 0.1-8 wt.% of the additive and its decomposition product, 11-19 wt.% of silicon and 66.4-88.9 wt.% of aluminum.    DESCRIPTION OF DRAWING(S) - The figure schematically illustrates a cross-sectional view of the solar cell.    Solar cell (400)    Positive-type region (410)    Negative-type region (420)    Metal front electrode (451)    Eutectic layer (462)