Bihar Rooftop Solar: What Is Surplus Power Worth?

A subsidy can make rooftop solar cheaper to purchase. But what determines whether the installation delivers worthwhile savings over the following years?

Bihar’s proposed metering amendments bring that second question into focus. For a buyer, the important distinction is between electricity generated and the financial value actually realised from it.

What is being proposed?

Mercom reports a proposed 500 kW net-metering cap and financial-year-end excess compensation at 50% of the feed-in tariff -> Bihar Proposes 500 kW Cap for Rooftop Solar Net Metering.

BERC lists the amendment as a draft -> Draft Regulations on BERC (Rooftop Solar Grid Interactive Systems Based on Net and Gross Metering) (Second Amendment) Regulation, 2026.

Those facts justify examining a quotation’s assumptions. They do not justify treating the proposal as an implemented rule.

The reported year-end provision also should not be interpreted as a blanket halving of the value of every exported unit. The complete settlement mechanism must be understood before drawing that conclusion.

Why can two units of solar electricity have different values?

A useful financial model separates how the electricity is used.

Electricity category	Financial question
Consumed at the property	Which electricity purchase or charge does it avoid?
Exported and adjusted against imports	What adjustment does the applicable billing arrangement permit?
Left as surplus at settlement	What payment or credit applies to that residual balance?

This is a framework for reviewing a quotation, not a statement that every Bihar connection currently follows an identical settlement process.

If a proposal multiplies all projected generation by one retail tariff, ask why that valuation is appropriate. The calculation may need separate assumptions for each category.

Fixed charges and other bill components should also be treated separately where solar generation does not remove them.

What does “50% of the feed-in tariff” mean?

It means half of the relevant feed-in tariff, if that reported proposal is adopted and applies to the specified surplus.

It does not mean half of the household’s retail electricity tariff. Nor does the percentage alone identify a rupee-per-unit payment.

A clearly hypothetical example

Assume, solely for illustration:

• The applicable feed-in tariff is ₹4 per kWh.
• Eligible residual surplus is 1,000 kWh.
• The settlement payment equals 50% of that tariff.

The assumed payment would be:

1,000 × ₹4 × 50% = ₹2,000.

These are invented scenario inputs, not Bihar’s verified tariff or a forecast of an actual customer’s payment. The example illustrates why the tariff definition matters.

It also provides no basis for calculating a reduction from the existing arrangement, because that would require a verified, comparable baseline.

Does the capacity cap matter equally to every buyer?

No. A proposed ceiling is an eligibility question; annual surplus is an operating-economics question.

A small household system can be well below 500 kW and still need to examine the value of residual exports. Conversely, a larger commercial or institutional proposal may need to resolve capacity eligibility before considering its savings.

The full draft is needed to establish how the reported limit interacts with sanctioned load, other metering arrangements and existing approvals. Those details should not be inferred from the headline.

Why subsidy cannot settle the investment case

Vantage previously discussed Bihar’s additional support for eligible rooftop-solar consumers -> Bihar adds up to Rs.20,000 state subsidy for rooftop solar.

That assistance addresses part of the installation cost. Annual economic benefit depends on electricity use, billing treatment and the costs of operating the system.

A transparent proposal should show both sides:

• Initial expenditure: installation price, eligibility-dependent assistance and financing costs.
• Ongoing benefit: avoided electricity spending and applicable export or surplus credits, less relevant operating costs.

A one-time contribution should not be added repeatedly to annual savings.

What should change in a quotation?

Ask for a current-rules calculation and a separately labelled proposal scenario.

Both should use the same generation and consumption assumptions so the effect of the settlement change can be examined. If the installer changes several assumptions simultaneously, it becomes harder to identify what caused the result.

Also ask whether the financial model assumes that all generation can be used or credited. A system sized mainly to maximise panel capacity may create surplus whose value differs from electricity used at the property.

We have previously examined how consumption, roof conditions and future needs affect sizing -> How to Determine the Solar Capacity Needed for Your Home?.

The conclusion is conditional: the proposal makes export assumptions worth revisiting, but it does not establish that solar has become unattractive. The investment case needs the applicable final rules and a model that follows the electricity through to its actual financial value.

FAQ

Have the proposed amendments become final?

The reviewed official page lists a draft. A final notification and effective date were not established.

Is 500 kW a recommended household system size?

No. It is the reported proposed net-metering ceiling, not a sizing recommendation.

Does the proposal halve every exported unit’s value?

That is not established. The accessible reporting refers specifically to excess electricity at the financial year’s end.

Is the feed-in tariff the same as the retail tariff?

They are different concepts. The applicable values and definitions must be verified.

What is the actual proposed payment in rupees per unit?

The reviewed evidence does not establish the applicable feed-in tariff needed to calculate that amount.

Does receiving a subsidy guarantee a short payback?

No. Payback also depends on generation, consumption, billing treatment, operating costs and financing.

Sources

Click an article title to view the source.

• Bihar Proposes 500 kW Cap for Rooftop Solar Net Metering published on 9 October 2026 in Mercom India.
• Draft Regulations on BERC (Rooftop Solar Grid Interactive Systems Based on Net and Gross Metering) (Second Amendment) Regulation, 2026 listed by Bihar Electricity Regulatory Commission; publication date not established. Reviewed on 11 October 2026.
• Bihar adds up to Rs.20,000 state subsidy for rooftop solar published on 23 September 2026 in Vantage Radar.
• How to Determine the Solar Capacity Needed for Your Home? published on 29 September 2026 in Vantage InSights.

Evidence Caveats

BERC’s draft listing was inspected, but the complete draft document was not retrieved. Mercom’s accessible material supports the reported capacity ceiling and year-end compensation proposal; its restricted article content was not accessed.

The reviewed evidence does not establish the final commencement date, treatment of existing installations, detailed credit-adjustment mechanism or applicable feed-in tariff. It therefore cannot support a quantified change in customer savings.

The ₹2,000 calculation uses explicitly hypothetical inputs. No current subsidy entitlement, installation price or project payback is verified for an individual consumer.

Does your installer separate self-consumption, adjusted exports and residual surplus? Share a calculation you have tested, or explain which missing assumption prevents you from trusting it, in the attached forum discussion.

Disclaimer

This article provides general information and editorial analysis, not personalised financial or legal advice. Confirm the notified regulations, applicable tariff, eligibility and connection requirements with the relevant authorities before committing to an installation.