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

Canonical: https://senseible.earth/answers/hybrid-solar-tray-dryer-wood-saving

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](https://senseible.earth/green-loan-check)
- [Efficient 96-tray dryer](https://senseible.earth/answers/efficient-tray-dryer-wood-saving-chemical-unit)
- [Solar dryers in agro processing](https://senseible.earth/answers/solar-dryer-agro-processing-co2)
- [Efficient wood hot air generator](https://senseible.earth/answers/efficient-wood-hot-air-generator-saving)

Sources: [BEE, Detailed project report: hybrid solar tray dryer, 96 trays, Ahmedabad chemical cluster (2010, SAMEEEKSHA)](https://sameeeksha.org/pdf/dpr/Ah_96.pdf), [BEE, Detailed project report: energy efficient tray dryer, 96 trays, Ahmedabad chemical cluster (2010, SAMEEEKSHA)](https://sameeeksha.org/pdf/dpr/Ahmedabad_96.pdf), [IPCC 2006 Guidelines, Volume 2 Energy, Table 1.2 (net calorific values) and Chapter 2 tables](https://www.ipcc-nggip.iges.or.jp/public/2006gl/vol2.html), [GHG Protocol Corporate Standard (biogenic CO2 reported separately from the scopes)](https://ghgprotocol.org/corporate-standard), [CEA, CO2 Baseline Database for the Indian Power Sector, version 22.0 (FY 2025-26 grid factor)](https://cea.nic.in/cdm-co2-baseline-view?mappingId=234&lang=en)

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.