Before sizing a solar array, map how the factory uses electricity across shifts and seasons. Measure before modeling. Review at least 12 months of utility bills and interval-meter data, noting weekend shutdowns, start-up surges, and large motors. The U.S. Energy Information Administration’s 2018 Manufacturing Energy Consumption Survey estimates that U.S. manufacturing used about 26 quadrillion Btu of energy. That scale makes process schedules and peak demand important; a monthly bill alone can hide costly short-lived spikes.

Then assess orientation, shading, maintenance access, and the distance to electrical equipment. NREL’s 2016 rooftop solar technical-potential assessment estimated 1,118 gigawatts of capacity across U.S. rooftops, but this is a national estimate—not a forecast for any factory. A local site may have less usable area than it appears. Check likely system output against daytime demand, utility export limits, and planned production changes. Parking canopies or nearby land may help when the roof is unsuitable, though they add design and connection costs. One estimate may still be wrong; validate it with site measurements and interval-load data.

Before choosing panels, define what the factory needs solar power to achieve. Is the target lower daytime electricity costs, reduced emissions, or more predictable energy spending? Start with the load. Review at least twelve months of utility bills alongside interval data, production schedules, and seasonal shutdowns. A factory running heavy equipment at noon may use solar power directly. A night-shift facility may need storage or a different system design.

Set practical limits, too. Identify critical equipment, acceptable backup duration, available roof or land, and a budget range. Then test whether the site can support the plan. A roof inspection should check structural capacity, age, drainage, and shaded areas. Electrical engineers can assess connection points and capacity constraints. Ask for production estimates that account for local weather, panel orientation, equipment losses, and future degradation. Neat projections can still mislead.

Compare expected savings with installation, maintenance, insurance, and financing costs. Include possible changes in electricity rates and any costs tied to exporting excess power. Check how the project fits planned upgrades; a roof replacement next year could change the numbers. Early estimates are imperfect. That is normal. Record assumptions clearly, then test a cautious scenario with lower generation and higher costs. If the project only works under ideal conditions, the goals or system size may need another look.

A factory solar plan should begin with interval electricity data, not roof area alone. Compare hourly demand across seasons, then identify which production shifts can use daytime power. Inspect the roof’s age, shading, drainage, and structural capacity before fixing a system size. A newer roof may support a larger array; an aging one could make repairs costly later. Check utility connection limits early, too.

Model several designs: rooftop panels, parking canopies, or a phased installation. Include inverter replacement, maintenance, expected panel output, and any battery costs. Batteries can help manage short demand peaks, but they are not automatically worthwhile. For financing, compare cash purchase, a loan, and third-party arrangements using the same assumptions and contract period. Review fees, performance guarantees, escalation clauses, and who handles repairs. A polished spreadsheet can still overlook a production shutdown or changing shift schedule. I would keep a contingency in the budget.

Tips: Ask for a one-line electrical diagram and a monthly savings estimate. Check that the estimate reflects your actual tariff and demand charges. Get roof and interconnection reviews before signing. If forecasts feel overly certain, ask what happens when output falls short.

Before a factory moves toward solar power, inspect the roof and the electrical system. Check for leaks, corrosion, weak areas, and equipment that may cast shadows. A structural engineer can confirm whether the roof can support panels and mounting hardware. Review at least a year of electricity bills and production schedules, too. These records help estimate demand and identify when the factory uses the most power. Small details matter.

Plan the installation around daily operations. Map access routes, crane positions, work zones, and emergency exits before equipment arrives. Coordinate planned shutdowns with production staff and the electrical contractor; an unexpected outage can disrupt more than the installation. Confirm that inverters, cables, and switchgear match the site’s load and available space. Keep clear records of inspections and system settings. One easy-to-miss issue is future roof maintenance: leave safe access to drains, vents, and service areas. The layout may look less tidy, but that trade-off is worth considering.