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Solar Construction Site Calculator

Size portable solar to replace your diesel generator on site. Select equipment, enter project duration — get solar kW, battery bank, project diesel savings, and rent vs buy analysis.

Equipment checklist
kW
Project details
weeks
$/liter
Portable solar system for construction site
4.8 kW solar replaces ~85% of generator
Peak load (checklist)3.0 kW peak
Effective load (diversity 65%)2.0 kW avg
Daily energy use19.5 kWh/day
Portable solar array12 × 400W panels (4.8 kW)
Battery bank20 kWh (8-hr buffer)
Generator replacement~85% runtime reduction
Daily diesel savings$6.08/day
Total project fuel savings$122
Total project savings (incl. maintenance)$377
CO₂ reduced this project0.2 tons CO₂
Purchase cost$28,890
Rental cost (this project)$4,644 ($1,161/wk)
Buy vs rent verdictBuy saves $24,246 vs renting
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How to Use This Calculator

Check your site equipment

Tick each category of equipment you'll run on site: power tools and compressor (2kW), LED site lighting (1kW), office or break trailer with HVAC (3kW), and water pump for dust control (1kW). Add any other loads (welding, concrete mixer, additional HVAC) in the extra field. The calculator applies a 65% diversity factor since not all equipment runs simultaneously — a realistic assumption for most construction sites.

Set project duration and location

Enter your project duration in weeks. This drives the total diesel savings calculation and the rental vs. purchase comparison. Location determines peak sun hours — even a cloudy Seattle site (3.6 PSH) can generate significant solar energy over a long project. Remote sites often have higher delivered diesel costs, making solar more attractive.

Read the buy vs. rent verdict

For short projects (under 4 weeks), renting portable solar equipment usually beats buying. For longer projects (12+ weeks), owning the system and reusing it across projects is typically more cost-effective. The calculator shows both options so you can make the right decision for your situation.

The Formula

Peak Load = Sum of checked equipment watts + extra kW × 1000 Effective Load = Peak Load × 0.65 diversity factor Daily kWh = Effective kW × 10 work hours Solar kW = Daily kWh × 1000 ÷ PSH ÷ 0.82 efficiency Battery kWh = Effective kW × 8 hours ÷ 0.80 DoD Generator Replacement = 85% runtime reduction Daily Diesel Saved = Daily kWh × 0.85 ÷ 3.0 kWh/L Project Diesel Savings = Daily Diesel Saved × Project Days × Diesel $/L Project Total Savings = Fuel Savings + $15/day maintenance savings CO₂ Saved = Daily kWh × 0.85 × Project Days × 0.74 kg/kWh Purchase Cost = Solar kW × $2,800/kW + Battery kWh × $700/kWh + $1,800 BOS Rental Cost = Solar kW × $120/wk + Battery kWh × $30/wk × Weeks

The 65% diversity factor reflects that tools, office HVAC, and the water pump rarely all run at their peak simultaneously. If your site is unusual (all equipment running during an 8-hour window), remove the diversity factor and size to 100% of peak load. The 10-hour workday assumption covers most commercial and residential construction schedules.

Example

Hendricks Construction — 12-week commercial build in Dallas

A general contractor is running a 12-week commercial renovation in Dallas. They have power tools, LED lighting, an office trailer, and a water pump on site. Diesel is $1.10/L locally.

EquipmentTools + Lighting + Trailer + Pump = 7 kW peak
Effective load4.55 kW (65% diversity)
LocationDallas, TX (5.4 PSH)
Duration12 weeks
Diesel$1.10/L

Result

Daily kWh45.5 kWh/day
Solar array10.4 kW (26 × 400W panels)
Battery bank45.5 kWh buffer
Project fuel savings~$3,100
Total project savings~$4,200 (incl. maintenance)
CO₂ reduced~1.7 tons

Over 12 weeks, the solar system saves Hendricks Construction over $4,200 in diesel and generator maintenance costs. Purchasing the system at ~$38,000 makes sense if reused across 3+ projects — or renting at ~$10,400 for this project is the right call for a one-time use.

FAQ

For most light-to-medium construction work, yes — a properly sized solar + battery system can eliminate the diesel generator entirely. Heavy construction with large welding equipment, concrete pumps, or multiple compressors may still need a small backup generator for peak demand spikes. The typical approach is solar handles 85% of energy, with a small generator (rather than a large continuously running one) as backup. This "solar-diesel hybrid" approach reduces fuel costs by 70-85% and dramatically reduces noise, fumes, and maintenance.
The break-even point is typically 8-14 weeks. For projects under 8 weeks, renting portable solar tower lights and battery stations is more cost-effective. For projects over 14 weeks, or if you have multiple upcoming projects, purchasing is better. Consider that owned equipment builds equity, can be depreciated, and is available immediately without lead time. Equipment rental companies typically charge $100-200/week per 400W panel equivalent and $25-50/week per kWh of battery storage.
The main options are: (1) Solar light towers — portable trailer-mounted towers with 4-6 solar panels and integrated LED lights, perfect for site lighting. (2) Portable solar generators — units like EcoFlow Delta Pro or Goal Zero Yeti for smaller loads. (3) Containerized solar systems — shipping container-based systems with 10-50kW solar and large battery banks for full site power. (4) Custom temporary systems — panels mounted on scaffolding or site fencing, which is increasingly common on urban infill projects where generators are banned during certain hours.
A typical construction site diesel generator runs at 70-85 dB at 7 meters — equivalent to a vacuum cleaner running continuously. Solar systems with battery storage are nearly silent (only inverter cooling fan noise, ~45dB). This matters enormously for urban construction: many cities restrict generator operation to daytime hours, and battery systems can bridge overnight periods. Emissions-wise, a 10kW diesel genset running 10 hours/day emits roughly 75kg of CO2 daily — a solar hybrid eliminates 60-70kg of that.
The diversity factor (65% used here) accounts for the fact that not all equipment runs at full load simultaneously. Your angle grinder, office AC, and water pump rarely all peak at the same moment. Without a diversity factor, you'd significantly over-size the solar system. For sites where simultaneous operation is common (e.g., welding while the office runs full AC while the pump runs), use a higher diversity factor or add your loads to the "additional equipment" field. OSHA and NEC recommend diversity factors of 0.5-0.8 depending on load type.

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🔋 Battery Bank Calculator
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⚡ Power Consumption Calculator
Calculate daily watt-hours for any list of equipment or appliances.

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  title="Solar Construction Site Calculator"></iframe>