Last week we cruised through an average travel costs calculation for your solar estimate. This week we will go into a detailed mode! The other approach to breaking down travel costs involves getting closer: project level detail. Really it’s unit price estimating in action. In a PV system estimate, this method uses job hours and distance to the site. Basically the math incorporates the number of trips to the site your crews will take, the number of trucks they are taking, and the number of person hours billed to those trips. Step 1: figure out how many trips you team is going to be doing. This can be done by dividing your total construction hours by your person hours per day during construction (translation: calculate the number of construction days). Finish up with multiplying the number of construction days by the travel costs. In math terms:
( <total construction hours> / <construction person hours per day> ) x <travel costs>
Right, let’s not skip determining the travel costs. Well, I typically break travel costs into two values: Mileage costs and labor costs. Take the round trip mileage (say 50 miles one way x 2 = 100 miles per trip) and multiply it by your cost per mile to drive the trucks (say $0.55/mile gives $55/truck/day). The labor costs are the round trip travel time (50 miles through city streets at rush hour could average 20 miles per hour giving 5 person hours of travel) multiplied by the labor rate (say $20/hr so each trip costs $100/person/day). Don’t forget to account for all the folks in the truck; you must include them. Just to finish off the math then, the total travel cost in this solar bid is $55 * [# of days] + $100 * [# of days]. In more generic terms:
( <cost per mile> x <round trip miles> + <cost per hour> x <round trip hours> ) x <# of days>
One thing to keep in mind is your company’s travel policy. When determining the person hours to travel to the site and back, your company policy can heavily influence actual charges. For projects far from home, the company might opt to rent a hotel room and pay per diem. Or the company might expect the crew members to show up directly on site every day and have very little travel expense outside of moving the materials from the warehouse to the job site.
It was fun to see some of you at the Solar Software Summit on Tuesday. I hope to catch up with more of you at Intersolar in July.