I was manager of several quarries and sand plants. All were run by shore power, as diesel generation was too expensive. At the last plant I ran, we found the local electric coop had a special deal if we used off peak power. For 3 years, we ran the plant screening/washing operation at night from May1, until Oct.1. The loading/shipping, stripping took place during the day. Our electric savings was huge each year we did this. You might want to see if your local power company offers any deals like this.