Net metering and net billing sound like the same thing. They are not. The difference between them can add or subtract a year from your solar payback period — and Rajasthan’s 2021 regulatory amendment changed which regime applies to whom. If you own or are considering a solar system above 3 kW in Rajasthan, you need to understand this.

The Simple Version

Net Metering: Whatever you export to the grid earns you a credit at the same rate as what you pay to import. Export 1 unit, get credited for 1 unit worth of imports. It’s a 1-for-1 trade.

Net Billing: Whatever you export earns you a credit at the export rate (set by RERC, typically ₹3.14-3.65/unit), but you import at the full retail tariff (₹6-9/unit depending on slab). The difference is the utility’s margin on the transaction.

The gap between ₹3.14 (export) and ₹8.55 (residential import at >500 units/month) is where your returns evaporate if your system is over-sized or generating at times when you don’t consume the power yourself.

Who Gets What in Rajasthan (Post-2021)

The Maths of the Mismatch

Consider a 100 kW commercial system in Jodhpur. It generates 1,50,000 units per year. If the business uses 1,20,000 units (self-consumption) and exports 30,000 units:

This is why, under net billing, the golden rule of solar system design is: size your system to match your daytime consumption, not your total consumption. Export should be minimised to zero if possible, because every exported unit earns roughly one-third of its avoided import value.

The 12-Month Banking System

Both net metering and net billing in Rajasthan use a 12-month banking period. Credits that accumulate (export exceeding import in a given month) are carried forward and can be offset against future months’ consumption. At the end of the 12-month cycle (typically April), any remaining credit balance is paid out at the applicable export rate — or lapses, depending on DISCOM interpretation.

For residential users with summer export surplus (panels peak in summer, consumption can also peak in summer for AC-heavy homes), this banking is valuable — it offsets winter bills when generation dips.

Designing Around Net Billing

If you are a commercial or industrial consumer in Rajasthan, here is how to design your system intelligently under net billing:

1. Load profile analysis first. Map your hourly consumption during 8am-5pm (peak solar hours). This is the consumption your solar system should target covering.
2. Size at 80-90% of daytime load, not total load. Slightly under-sized is better than over-sized under net billing.
3. Consider time-shifting loads. Running heavy loads (compressors, chillers, pumps) during solar hours maximises self-consumption and avoids the export rate penalty.
4. Add battery storage selectively. For commercial users with evening peak loads, a small battery buffer (30-50 kWh) can absorb excess solar and dispatch it in the evening — entirely avoiding the low export rate.

Net billing is not a scheme to be feared — it is a design constraint to be respected. Properly designed, a commercial solar system under net billing still delivers 25-35% ROI. Improperly sized, you could see under 15%.