Renewable energy glossary

If a term here appears in one of our models, this is what we mean by it. Where a tender defines something differently, the tender wins, and the model is configured to match it.

151 terms shown

A

AC capacity

Project & capacity

The capacity measured at the inverter or turbine output, which is what the grid sees and what a contract is written against. Solar projects normally install more DC than AC.

ALMM

Approved List of Models and ManufacturersPolicy & regulation

The MNRE-maintained list of module, cell and wind turbine models eligible for government-supported projects. If a model is not on the list it cannot be used, so the list is a procurement constraint before it is a policy instrument.

Ancillary services

Markets & trading

Grid support products such as frequency response and reserves, procured separately from energy. Batteries can earn from them, but only where the market design and the PPA both allow it.

Anemometer

Generation

The instrument on a met mast that records wind speed. A year or more of on-site anemometry is what turns a desktop wind estimate into a bankable one.

Arbitrage

Markets & trading

Charging when prices are low and discharging when they are high, within whatever cycle limits the contract and the warranty allow.

Assured Peak

Contracts & tenders

An obligation to discharge during a defined peak window every day, with a penalty for failing to.

Augmentation

Storage

Adding battery capacity later in the project's life to offset degradation, either in fixed years chosen up front or triggered when performance falls below a threshold.

Auxiliary consumption

Generation

Energy the plant consumes itself, for trackers, inverters, HVAC and the battery's own thermal management. It sits between gross generation and what is actually injected.

Availability

Generation

The share of a period in which the project met its obligation. Tenders define it monthly, annually, or block by block, and each definition carries its own penalty.

B

Balance of system

BoSProject & capacity

Everything in the plant that is not the module, turbine or battery cell: structures, cabling, transformers, inverters, roads, evacuation. Usually the part where cost estimates go wrong.

Bankability

Commercial & finance

Whether a lender will fund the project on the terms assumed. Resource data, offtaker credit, technology track record and contract enforceability all feed into it.

Banking

Contracts & tenders

Holding energy back now so it is available when the contract most needs it. In a firm-supply obligation this is the core of how the commitment is met. Under open access rules the same word means depositing surplus with the discom and drawing it later.

Battery banks

Storage

How many identical battery units the project installs. Total storage is the per-bank capacity multiplied by the number of banks.

Bayesian optimisation

Optimisation & modelling

A search method that uses results already computed to decide which configuration to test next, rather than sweeping the whole space. It is how a search over thousands of combinations finishes in minutes instead of weeks.

BESS

Battery Energy Storage SystemStorage

The storage the project dispatches from. Sized in two numbers that must both be stated: power in MW and energy in MWh.

Bid bond

EMDContracts & tenders

The earnest money deposit lodged with a bid, forfeited if the bidder walks away after award. It sets a floor on how casually a tariff can be quoted.

Bifacial module

Generation

A module that generates from both faces, picking up ground-reflected light on the rear. The gain depends on albedo, mounting height and row spacing, so the uplift claimed in a datasheet rarely survives a site.

Blended tariff

Commercial & finance

The weighted average price across all the ways a project sells energy, contracted and merchant. It is the number that matters to returns, not the headline bid tariff.

Brownfield

Project & capacity

Expanding or adding to an existing site, usually reusing the substation and evacuation already built. The connection cost that dominates a greenfield budget is already sunk.

C

Capex

Commercial & finance

The upfront build cost. In a bid model it is the single input the tariff is most sensitive to, and the one with the widest honest range.

Carbon credit

Policy & regulation

A tradable unit representing one tonne of CO2 equivalent avoided or removed, issued under a standard such as VERRA or the Gold Standard. Renewable generation in India rarely qualifies now, because grid-connected RE is treated as business-as-usual.

Charging source

Storage

Whether the battery may charge from solar, from wind, from both, or from the grid. It changes which surplus is available to store and which is exported.

Clipping

Generation

Energy lost when DC output exceeds what the inverter can pass. A degree of clipping is deliberate, because oversizing DC lifts output in every hour that is not the peak.

COD

Commercial Operation DateProject & capacity

The date the project is certified as operating commercially and the tariff starts running. Missing it triggers liquidated damages and, past a threshold, termination.

Co-located

Project & capacity

Solar, wind and storage sharing one connection point and one contract, rather than being modelled as separate projects.

Commissioning

Project & capacity

The staged process of energising and testing the plant before COD. Partial commissioning is often allowed, and the rules for it are worth reading before a schedule is committed.

Connectivity

Grid & transmission

The maximum power the grid connection physically allows the project to inject. The difference between connectivity and contracted capacity is the over-injection headroom.

Contracted capacity

CCProject & capacity

The capacity the offtaker contracts for, and the level every availability and penalty obligation is measured against.

C-rate

Storage

How fast a battery can be charged or discharged relative to its energy capacity. A two-hour battery is a 0.5C battery.

CTU

Central Transmission UtilityGrid & transmission

The body responsible for the inter-state transmission system and for granting connectivity to it. In India the CTU function sits with CTUIL.

CUF

Capacity Utilisation FactorGeneration

Energy actually generated over a period, divided by the energy the plant would have produced running at its contracted capacity for the whole period. Tenders often ask the developer to declare a CUF and then penalise falling short of it.

Curtailment

Grid & transmission

Generation deliberately held back, because the grid cannot take it, because it would breach the connectivity limit, or on instruction.

Cut-in and cut-out speed

Generation

The wind speeds at which a turbine starts generating and shuts down for safety. Both matter more than rated power when a site is either very light or very gusty.

Cycles per day

Storage

How many times the battery may be charged and discharged in a day. Tenders and warranties both cap it, and the cap shapes what dispatch strategies are available.

D

DAM

Day Ahead MarketMarkets & trading

Power traded a day before delivery, in defined time blocks.

DC:AC ratio

ILRGeneration

Installed DC capacity divided by inverter AC capacity, also called the inverter loading ratio. Raising it lifts generation in weak light and costs clipped energy at noon, which is why it is an optimisation variable and not a rule of thumb.

Deemed generation

Contracts & tenders

Energy the project is paid for although it was not delivered, because the offtaker or the grid prevented delivery. Whether curtailment counts as deemed generation is one of the more valuable clauses in a PPA.

Degradation

Storage

The annual loss of capacity in modules and batteries. Modelled as a curve rather than a single number, because it drives both revenue decline and the timing of augmentation.

Depth of discharge

DoDStorage

How far a battery is drawn down before recharging, as a share of usable capacity. Deeper cycling gets more energy out of the same asset and shortens its life, and the warranty prices that trade directly.

DFR

Demand Fulfilment RatioContracts & tenders

In one time block, scheduled injection divided by contracted capacity, capped at 1. The basis for time-block penalties.

Discom

Policy & regulation

The state distribution company that buys power and sells it to end consumers. Its payment record is usually the largest single risk in an Indian utility-scale project.

Dispatch

Optimisation & modelling

The hour-by-hour decision on what to generate, what to store, what to export and what to sell. Every configuration is only as good as the dispatch logic run against it.

DSCR

Debt Service Coverage RatioCommercial & finance

Cash available for debt service divided by debt service due in the same period. Lenders size debt off the minimum and the average, so the worst year matters as much as the mean.

DSM

Deviation Settlement MechanismMarkets & trading

The charge for injecting more or less than scheduled. It converts forecasting error directly into cash, and is why forecasting and scheduling is a line item and not an afterthought.

DSRA

Debt Service Reserve AccountCommercial & finance

A cash reserve, usually two quarters of debt service, that the lender requires to be funded and kept funded. It is trapped capital and belongs in the returns calculation.

Duration

storageStorage

How many hours a battery can discharge at rated power. A 100 MW / 400 MWh system is four-hour duration. Tender constructs are usually written around duration, not energy.

E

Energy yield

Generation

The total energy a plant is expected to deliver in a year after all losses. The number a lender underwrites, expressed at P50 and P90.

EPC

Engineering, Procurement and ConstructionProject & capacity

The contractor that builds the plant, and the contract that transfers construction risk. A fixed-price turnkey EPC is what makes a capex number credible.

Equity IRR

Commercial & finance

The return to the equity holder after debt service, as opposed to the return on the whole project. Leverage moves it a long way, which is why the two are never quoted interchangeably.

Escalation

Commercial & finance

A contracted annual increase, usually in tariff or in O&M cost. A flat tariff over 25 years against escalating costs is a real erosion, and it belongs in the model explicitly.

Escrow account

Commercial & finance

An account through which project revenue is routed so lenders are paid before the sponsor. Standard in Indian project finance, and it constrains how freely cash can be moved.

Evacuation

Grid & transmission

The transmission infrastructure that carries power from the plant to the grid: pooling substation, transmission line and bay. Frequently the longest-lead item on a project.

F

FDRE

Firm and Dispatchable Renewable EnergyContracts & tenders

The hardest obligation in the Indian market. The project must deliver firm, dependable power meeting minimum availability targets in both peak and off-peak hours, often to different levels in different months. Storage is managed by deliberately reserving energy for upcoming peak windows.

Feed-in tariff

FiTPolicy & regulation

An administratively set price at which a generator is paid, as opposed to a price discovered by auction. Largely displaced in India by reverse bidding, still relevant in several export markets.

Financial close

Commercial & finance

The point at which all financing documents are signed and drawdown conditions are met. Everything before it is a plan and everything after it is a schedule.

Firm power

Contracts & tenders

Power the offtaker can count on being there at a stated level, as distinct from whatever the resource happens to deliver. Firming a renewable plant means storage, overbuild, or both.

Force majeure

Contracts & tenders

Events outside either party's control that suspend obligations. What is inside the definition and what is outside it is contested in nearly every tender.

Forecasting and scheduling

Markets & trading

Declaring in advance what the plant will inject in each time block. Accuracy is enforced through DSM charges, so it is an operating cost with a direct link to modelling quality.

Frequency response

Grid & transmission

Adjusting output within seconds to arrest a change in grid frequency. Batteries are technically well suited to it, and whether it is a revenue line depends entirely on the market design.

G

GDAM

Green Day Ahead MarketMarkets & trading

The day-ahead market restricted to renewable power, cleared alongside the conventional day-ahead market.

Generation profile

Generation

The hour-by-hour output of the plant across a year, which is what every dispatch decision in the model is made against.

GHI, DNI and POA

Generation

Global horizontal irradiance, direct normal irradiance, and plane-of-array irradiance. GHI is what the site receives, POA is what the modules actually see after tilt and tracking, and the gap between the two is a design decision.

GNA

General Network AccessGrid & transmission

The regime that replaced project-specific long-term access with a general right to inject up to a quantum at a node. It changes how transmission capacity is booked and what a developer is exposed to if a project slips.

Green open access

Policy & regulation

The rules allowing a consumer to buy renewable power directly from a generator over the network, subject to charges levied by the state. The economics turn almost entirely on those state charges.

Grid code

Grid & transmission

The technical rules a plant must meet to connect and stay connected: reactive power, fault ride-through, harmonics, ramping. Non-negotiable, and cheaper to design for than to retrofit.

Grid-forming inverter

Generation

An inverter that can establish voltage and frequency itself rather than following an existing grid. Increasingly required as inverter-based generation displaces synchronous machines.

H

Half-cut cell

Generation

A module built from cells cut in half, which lowers resistive loss and improves behaviour under partial shading. Standard on current mainstream modules.

Hub height

Generation

The height of the turbine nacelle above ground. Wind speed rises with height, so hub height is one of the few levers that improves a mediocre wind site.

Hurdle rate

Commercial & finance

The minimum return an investor will accept before committing capital. In a bid it sets the floor under the tariff, and it is the number every optimisation is ultimately solving against.

Hybrid project

Project & capacity

Solar and wind, usually with storage, delivered under one contract at one connection point. The point is a smoother combined profile, not more capacity.

I

IEX

Indian Energy ExchangeMarkets & trading

India's largest power exchange, where day-ahead, real-time and green market segments are traded.

Injection

Grid & transmission

Energy actually delivered into the grid at the metering point, after auxiliary consumption and transformer losses. Contracts are settled on injection, not on generation.

Inverter

Generation

The unit converting DC from modules or a battery into grid-compatible AC. Central inverters are cheaper per MW, string inverters fail less catastrophically, and the choice shows up in availability figures.

IRR

Internal Rate of ReturnCommercial & finance

The discount rate at which the project's cash flows net to zero. Together with tariff it is the pair a bidder actually argues over.

ISTS charges

Policy & regulation

Charges for using the inter-state transmission system. Renewable projects commissioned within notified windows have received a waiver, phased out on a graded schedule, so the applicable percentage depends on the commissioning date. Getting that date wrong changes the viable tariff materially.

J

JMR

Joint Meter ReadingGrid & transmission

The meter reading taken jointly by the generator and the offtaker, and the record that settlement invoices are raised against. Disputes over energy accounting usually start here.

K

kWp

kilowatt-peakGeneration

Module capacity measured under standard test conditions. Solar DC capacity is quoted in kWp or MWp, which is why a plant described as 100 MW may have 130 MWp installed.

L

Land aggregation

Project & capacity

Assembling contiguous private land for a project, parcel by parcel. In practice the item most likely to delay COD, and the one least visible in a financial model.

LCOE

Levelised Cost of EnergyCommercial & finance

The lifetime cost of the project divided by the lifetime energy it delivers. The standard way to compare configurations that cost and produce different amounts.

LCOS

Levelised Cost of StorageCommercial & finance

The same calculation applied to a battery, per unit of energy discharged. Sensitive to cycle count, so a storage asset that sits idle has a terrible LCOS regardless of how cheaply it was bought.

Liquidated damages

LDContracts & tenders

Pre-agreed amounts payable for delay or underperformance, without the offtaker having to prove loss. Capped in most contracts, and the cap is worth checking before the schedule is.

LoA

Letter of AwardContracts & tenders

The document confirming a bidder has won, ahead of PPA signature. Clock on most milestones starts here.

Load following curve

Contracts & tenders

An obligation to match a demand curve supplied by the offtaker, hour by hour, rather than a flat or peak-only commitment.

M

Max SoC

Storage

The most energy the battery can hold, being the per-bank hourly capacity multiplied by the number of banks.

Merchant sale

Markets & trading

Selling energy on an exchange at the prevailing price rather than under a fixed-tariff contract. Higher expected revenue, and no revenue certainty for a lender to size debt against.

Merit order dispatch

Markets & trading

The order in which the system operator calls on generators, cheapest first. Renewables sit at the bottom of the cost stack, which is the basis for must-run status.

Metering point

Grid & transmission

The physical point at which energy is measured for settlement, usually the interconnection substation. Everything between the plant and this point is the developer's loss to bear.

MILP

Mixed Integer Linear ProgrammingOptimisation & modelling

The formulation used when a dispatch problem contains yes-or-no decisions, such as whether to charge in a given hour. It gives a provably optimal answer, at a computational cost that rises quickly with horizon length.

Must-run status

Policy & regulation

The regulatory status that prevents solar and wind from being curtailed for reasons other than grid security. Whether compensation follows a curtailment instruction is a separate question, answered in the PPA.

N

Nameplate capacity

Project & capacity

The rated capacity of the equipment as installed, before any contractual limit is applied. Distinct from contracted capacity, and the two are only equal by coincidence.

Net metering

Policy & regulation

An arrangement where a consumer's export offsets their import on the same meter. Capacity caps and state rules limit it to smaller rooftop systems in most of India.

NHPC

Policy & regulation

A central utility that runs renewable tenders as an intermediary procurer, alongside its hydro business.

Nodal agency

Policy & regulation

The body running a tender and signing the PPA, typically SECI, NTPC, NHPC or a state agency. Its credit standing is what a lender is really lending against.

NTPC

Policy & regulation

India's largest power producer, and an intermediary procurer in a large share of renewable tenders.

O

Objective function

Optimisation & modelling

What the optimisation is asked to maximise or minimise: lowest tariff at a target return, highest IRR at a fixed tariff, lowest penalty exposure. Change it and the winning configuration changes.

Off-peak

Contracts & tenders

The hours outside the contracted peak window. In an FDRE construct there is normally a separate, lower availability obligation in these hours, and it is not optional.

Offtaker

Contracts & tenders

The counterparty buying the power. Everything about the tariff a project can afford to bid follows from who this is.

O&M

Operations and MaintenanceCommercial & finance

The annual cost of running the plant. Usually quoted per MW per year with an escalation, and materially higher for wind and for anything with a battery in it.

Open access

Policy & regulation

The right of a consumer to buy power from a generator other than the local discom, using the network for a charge. The commercial basis of the C&I market.

Optimiser run

Optimisation & modelling

Ranges instead of fixed capacities. The model searches the space and returns the configuration that best meets the objective you set, whether lowest tariff or highest return.

Overbuild

Project & capacity

Installing more generation capacity than the contract requires, so the obligation is met in weak resource periods. Cheap compared with storage, and wasteful in every hour that is not weak.

Over-injection headroom

Project & capacity

Connectivity minus contracted capacity. Where surplus generation can go once the contracted obligation has been met. If the two are equal there is no headroom.

P

P50 and P90

Generation

Energy yield estimates with a 50 percent and a 90 percent probability of being exceeded. Equity works off P50 and lenders size debt off P90, which is why the gap between them is a financing variable.

Pareto front

Optimisation & modelling

The set of configurations where no objective can be improved without worsening another. What you look at when tariff and return are being traded off, instead of a single recommended answer.

Payment security mechanism

PSMContracts & tenders

The letter of credit, payment security fund or tripartite arrangement backing the offtaker's obligation. It is what separates a contracted receivable from a hopeful one.

Peak window

Contracts & tenders

The hours in which the contract requires a higher, firmer level of supply. Defined in the tender, often varying by season, and the single most demanding constraint on storage sizing.

Penalty multiplier

Contracts & tenders

The factor a shortfall is multiplied by to arrive at the amount payable. It is what turns a technical miss into a number on the balance sheet.

Performance ratio

PRGeneration

Actual output as a share of what the installed capacity should have produced under the irradiance received. The cleanest single measure of how well a solar plant is being run.

PLF

Plant Load FactorGeneration

The same ratio as CUF but measured against installed capacity rather than contracted capacity. Used here to decide when a battery has degraded enough to need augmenting.

Pooling substation

Grid & transmission

The substation where several projects combine output before evacuation. Shared cost, shared outage risk, and a common source of disputes over losses.

PPA

Power Purchase AgreementContracts & tenders

The contract to sell power at an agreed tariff for an agreed term. Its length sets the horizon for most of the financial model.

Project IRR

Commercial & finance

The return on total project cash flows before financing. The comparison used between configurations, because it is not distorted by leverage.

PSA

Power Sale AgreementContracts & tenders

The back-to-back contract between the intermediary procurer and the discom that finally takes the power. Awarded capacity with no signed PSA is not a pipeline, it is a queue.

Q

Quantum

Contracts & tenders

The volume of capacity or energy a contract covers. Worth stating explicitly whether a tender means MW at the delivery point, MWh per year, or both.

R

Ramp rate

Grid & transmission

How fast output can be changed, in MW per minute. Constrains what a plant can offer in ancillary services and what a grid code will permit it to do.

REC

Renewable Energy CertificatePolicy & regulation

A tradable certificate representing the green attribute of one MWh, separable from the energy itself. Used to meet renewable purchase obligations, and now issued under the Green Energy Certificate framework.

Repowering

Project & capacity

Replacing old turbines on a good wind site with larger modern machines. The resource and the land are already proven, which is what makes the economics work.

Resource assessment

Generation

The measurement and modelling that produces an energy yield estimate. Everything downstream, tariff included, is built on it, so its uncertainty is the uncertainty of the whole bid.

RPO

Renewable Purchase ObligationPolicy & regulation

The minimum share of power an obligated entity must source from renewables, set by trajectory and enforced by the state commission. Enforcement varies, and so does the value of an REC.

RTC

Round-the-ClockContracts & tenders

A contract requiring supply across all hours to a stated availability, rather than only when the resource is available. Usually met with a hybrid plant plus storage, and used interchangeably with FDRE in most Indian tenders.

RTE

Round Trip EfficiencyStorage

How much energy survives a full charge-then-discharge cycle. Entered as the percentage lost on each leg, so 7.5 percent each way is a round trip of roughly 85.6 percent.

RTM

Real Time MarketMarkets & trading

Power traded close to delivery, in short blocks. Where a forecasting error is either corrected or paid for.

S

SCADA

Generation

The control and monitoring system that runs the plant and produces the data every performance claim is settled against.

Search space

Optimisation & modelling

The full set of configurations defined by the ranges given: solar MW, wind MW, battery MW and MWh, and the dispatch rules. Its size is why exhaustive testing is not an option and why the search method matters.

SECI

Solar Energy Corporation of IndiaPolicy & regulation

The central nodal agency for renewable tenders, and the intermediary procurer in most large solar, hybrid and FDRE auctions.

Sensitivity analysis

Optimisation & modelling

Re-running the model with one input moved at a time to see which assumptions the answer actually depends on. Usually capex, resource and cost of debt, in that order.

Shortfall

Contracts & tenders

The gap between what the contract required in a period and what was delivered. Multiplied by the penalty multiplier, it is the number that appears on an invoice.

Single run

Optimisation & modelling

One configuration, fully modelled. You give exact capacities and the model reports what they produce and what they earn.

SoC

State of ChargeStorage

How much energy the battery currently holds at a point in time. The variable every dispatch rule is written around.

Specific yield

Generation

Annual energy per unit of installed capacity, in kWh per kWp. The cleanest way to compare sites, because it strips out project size.

STU

State Transmission UtilityGrid & transmission

The state body responsible for the intra-state transmission network and for connectivity to it, as distinct from the CTU.

Surplus energy

Project & capacity

Generation beyond what the contract requires in that hour. Where it goes, to storage, to an exchange, or nowhere, is a design decision worth several percent of return.

T

Take-or-pay

Contracts & tenders

An obligation on the offtaker to pay for a contracted volume whether or not it is drawn. Rare in Indian utility PPAs, more common in C&I contracts, and it moves the risk balance considerably.

Tariff

Commercial & finance

The price per unit of energy sold. In a competitive tender it is usually the number being bid.

Termination payment

Contracts & tenders

The amount payable if the contract ends early, and the mechanism by which debt gets repaid in that event. Lenders read this clause before they read the tariff.

Thermal mimic

Contracts & tenders

A tender construct requiring a renewable portfolio to deliver a load shape comparable to a thermal plant, with defined availability across the day and a declared annual CUF. The hardest configuration problem in the Indian market and the reason storage sizing and dispatch logic cannot be separated.

Time block

Markets & trading

The settlement interval used for scheduling and penalties, 15 minutes in the Indian market. Availability written per time block is a far stricter obligation than the same figure written annually.

Tracker

Generation

A mounting system that rotates modules to follow the sun, normally single-axis. Adds roughly a sixth to output and adds a moving part to every row.

Transmission losses

Grid & transmission

Energy lost between the plant and the delivery point, settled as a percentage deduction. Small per unit and large over 25 years.

Turbine class

Generation

The IEC classification matching a turbine to a wind regime, from high-wind Class I to low-wind Class III. Putting the wrong class on a site is a permanent, uncorrectable loss of yield.

U

Unit

kWhCommercial & finance

One kilowatt-hour. Tariffs in the Indian market are quoted per unit, and a paisa per unit across a large portfolio is a serious number.

Utility-scale

Project & capacity

Projects selling to a central or state procurer under a long-term PPA, as distinct from the C&I open access market. Different tender structures, different risk, different tariffs.

V

VGF

Viability Gap FundingPolicy & regulation

A capital subsidy awarded through a reverse auction to close the gap between a bid tariff and a viable one. Used where a fixed tariff is set and the bid variable is the support required.

VRE

Variable Renewable EnergyGeneration

Solar and wind, whose output follows the resource rather than an instruction. Every firming construct exists because of this one property.

W

WACC

Weighted Average Cost of CapitalCommercial & finance

The blended cost of debt and equity. In India this is where a large part of the tariff gap against global markets sits, and it is more sensitive to policy risk than to interest rates.

Wake losses

Generation

Output lost when turbines sit in the turbulent air behind other turbines. Layout is the only lever, and it trades directly against how much land has been secured.

Warranty

batteryStorage

The manufacturer's guarantee of retained capacity, conditional on cycle count, depth of discharge and temperature. Dispatch strategies that void it are not strategies.

Wheeling charges

Policy & regulation

Charges for using the distribution network to move power from a generator to a consumer under open access. Set by the state commission, and the main reason open access economics differ so sharply between states.

Wind-solar complementarity

Generation

The extent to which wind output fills the hours solar does not cover at a given site. Strong complementarity reduces how much storage a firm-supply obligation needs, and it is site-specific rather than a general rule.

Y

Yield assessment

Generation

The formal study producing P50 and P90 energy estimates from resource data, layout and loss assumptions. The document a lender's technical adviser will pull apart first.

Z

Zero-export limit

Grid & transmission

A control setting that prevents a captive or behind-the-meter plant from injecting into the grid. Common in C&I installations where the state does not permit export, and it caps how large the plant can usefully be.