Typically if you look at a circuit diagram, or are connecting batteries in series to increase output voltage potential, you will do the same thing. Positive of one battery to the negative of the next. Hooking all positives to all negatives will increase current potential, but not the voltage. Hooking them all in series instead (positive,negative,...) will increase the voltage, not the current.
You are thinking of all sources and loads in parallel when all positives are connected together. Your diagram sounds like some things need to be connected in series. At the output of the solar cell bank, and finally connected to load, then you will have positive to positive, negative to negative.
