Can a hybrid solar tray dryer cut wood use in a chemical drying room, and by how much?

Yes. BEE's Ahmedabad report has a 96-tray hybrid run 14 hours on solar-heated air and 16 on an efficient wood heater per 30 hour batch, saving 658 kg of wood a batch, 108.5 t a year. Cost Rs 8.01 lakh, payback 2.77 years (2010). Reported fossil CO2 barely changes.

How the hybrid runs

A solar panel heats air that is drawn into an insulated 96-tray cabinet. The report assumes 7 to 10 hours of usable sun a day. When the sun goes, digital controls switch the dryer to an efficient wood-fired hot air generator.

Per batch: 14 hours on solar, 16 hours on wood at 10.73 kg an hour, about 172 kg of wood, against 829 kg in the old 96-tray dryer.

Hybrid or efficient dryer: same report series, side by side

• Efficient dryer: Rs 3.86 lakh, 507 kg wood saved a batch, 130 batches, Rs 1.69 lakh a year, 2.28 years.
• Hybrid solar: Rs 8.01 lakh, 658 kg wood saved a batch, 165 batches, Rs 2.89 lakh a year, 2.77 years.
• The two reports assume different batch counts. At the same 130 batches, the hybrid saves about 85.5 t of wood, about Rs 2.27 lakh net, and pays back in about 3.5 years.
• Per batch, the hybrid's extra Rs 4.15 lakh buys about 150 kg more wood saved.

What it does to your footprint

The report claims 76 t of CO2 saved. That is wood CO2, which is biogenic and reported separately. In Scope 1 the methane and nitrous oxide from 108.5 t of wood are about 3.2 t CO2e; the dryer's 7,385 kWh are about 5.0 t in Scope 2. Reported fossil CO2 rises by about 2 t. The gain is wood and money, not Scope 1.

Before you buy

• Count your real batches a year; the payback depends on it.
• Check roof or yard space facing south for the panel, free of shade most of the day.
• Expect less solar hours in the monsoon months, and plan the wood heater for full load then.
• Ask the supplier for the solar panel's area and its air temperature at your batch's moisture.

165 batches a year, per the report (estimate)

• Wood saved: 657.7 kg x 165 = 108.5 t
• Money: 108.5 t x Rs 3,000 = Rs 3.26 lakh, less 7,385 kWh x Rs 5 = Rs 0.37 lakh: Rs 2.89 lakh
• Scope 1 methane and nitrous oxide avoided: 108.5 x 0.030 = 3.2 t CO2e
• Scope 2 added: 7,385 x 0.675 = 5.0 t CO2
• Biogenic CO2 avoided, reported separately: about 190 t

Wood at IPCC 2006 defaults with AR6 warming potentials; grid CEA FY 2025-26. The 130-batch comparison applies the report's per batch saving and costs to fewer batches.

What Senseible does here

Senseible reads your power bills into monthly CO2 records, so the dryer's extra kWh are counted. It has no built-in wood factor; weigh wood bought and use the figures worked out here. The green loan check covers what a lender wants for solar thermal equipment.

• Green loan readiness check
• Efficient 96-tray dryer
• Solar dryers in agro processing
• Efficient wood hot air generator

Sources: BEE, Detailed project report: hybrid solar tray dryer, 96 trays, Ahmedabad chemical cluster (2010, SAMEEEKSHA), BEE, Detailed project report: energy efficient tray dryer, 96 trays, Ahmedabad chemical cluster (2010, SAMEEEKSHA), IPCC 2006 Guidelines, Volume 2 Energy, Table 1.2 (net calorific values) and Chapter 2 tables, GHG Protocol Corporate Standard (biogenic CO2 reported separately from the scopes), CEA, CO2 Baseline Database for the Indian Power Sector, version 22.0 (FY 2025-26 grid factor)

Last reviewed 2026-10-31. Equipment figures are from a BEE SME programme project report; costs and paybacks are at that report's prices. Recheck with today's fuel and power prices and a current quote.