CHP Lighting vs Grid Decision Matrix

How it calculates

• CHP cost/kWh is derived from fuel input (capacity / elec efficiency) x gas cost + maintenance, divided by electrical output. Compare directly to blended grid rate.
• Blended grid rate weights on-peak and off-peak prices by photoperiod overlap. On-peak hours that fall within the light schedule drive most of the grid cost.
• Excess CHP capacity beyond lighting load is sold back at the grid sell-back rate (typically 2-5 cents/kWh for avoided-cost tariffs; higher with net-metering or feed-in tariffs). Annual sell-back revenue is included in net CHP profit.
• Heat credit offsets boiler fuel: thermal output (kW) x 0.03412 therms/kWh / boiler efficiency x gas price, prorated by heating months. Applies only during the heating season fraction.
• Fixture Efficacy (PPF/W) is the photosynthetic photon flux per watt of electrical input. Top-tier LEDs reach 3.0-3.5 umol/J; HPS fixtures are typically 1.7-1.9 umol/J.
• Light Use Efficiency (g/mol) converts photons to biomass. Lettuce: 0.8-1.2 g/mol; tomato fruit: 0.3-0.6 g/mol; cannabis flower: 0.4-0.8 g/mol; strawberry: 0.5-0.9 g/mol. Values depend on cultivar, CO2 enrichment, and environment optimization.
• DLI (mol/m2/day) shown is from supplemental light only. Total DLI in a greenhouse includes sunlight contribution (typically 5-25 mol/m2/day depending on latitude and season). Cost-per-mol metrics reflect supplemental lighting economics only.
• Cost per mol of light ($/mol) shows the true marginal cost of each mole of photons delivered to the canopy under CHP vs grid power. Lower cost/mol means more affordable light for yield.
• Lighting cost per kg of produce ($/kg) isolates the energy cost embedded in each kilogram of yield. Compare to sale price minus COGS to see if the lighting investment is economically justified.
• COGS (excl. lighting energy) covers labor, seeds/clones, nutrients, substrate, packaging, and post-harvest handling. Lighting energy is calculated separately so you can compare CHP vs grid impact on total cost structure.
• kWh per kg of produce shows the electrical intensity of your crop. Lower values indicate better light-to-yield conversion. Benchmark: leafy greens 5-15 kWh/kg; fruiting crops 20-60 kWh/kg; cannabis 40-100+ kWh/kg.
• Net Profit with CHP includes: gross crop profit from supplemental light minus CHP energy cost, plus heat credit (heating season), plus sell-back revenue from excess capacity. This is the complete economic picture.
• Crop Payback uses net CHP profit (crop revenue - COGS - CHP energy + heat credit + sell-back) to calculate how quickly the CHP system pays for itself through crop economics rather than energy savings alone.
• Break-even grid rate shows the grid electricity price at which CHP and grid become equal cost, accounting for heat credit and sell-back revenue offsets. If your actual blended rate exceeds this, CHP wins on energy alone.

What you enter

CHP Electrical Output(kW)

Electrical Efficiency(%)

Thermal Efficiency(%)

Supplemental Lighting Load(kW)

Daily Photoperiod (light hours)(hrs)

Natural Gas Cost(/therm)

Grid Rate (On-Peak)(/kWh)

Grid Rate (Off-Peak)(/kWh)

On-Peak Hours per Day(hrs)

Demand Charge(/kW/mo)

Grid Sell-Back Rate(/kWh)

Existing Boiler Efficiency(%)

Months Needing Heat(mo/yr)

CHP Maintenance Cost(/hr)

CHP System Installed Cost(total)

Fixture Efficacy (PPF/W)(µmol/J)

Light Use Efficiency (grams/mol)(g/mol)

Lit Canopy Area(m²)

Avg Produce Sale Price(/kg)

COGS (excl. lighting energy)(/kg)

What you get

Recommended Power Strategy

CHP Cost(/kWh)

Blended Grid Rate(/kWh)

Annual Energy Savings($)

Simple Payback(years)

Annual Crop Revenue($)

Net Profit with CHP($)

Net Profit with Grid($)

CHP Profit Advantage($)

CHP Cost per Mol($/mol)

Related calculators

• Battery Optimization
• DLC Compliance Checker
• Energy Consumption & Cost Calculator
• MEP Calculator