Solar & Alternative Energy Products Industry Terminology

AC-Coupled System

A system architecture where the battery energy storage connects on the AC side of the inverter, separate from the PV DC array. Favored for retrofits and multi-source microgrids; typically trades simplicity for slightly lower efficiency than DC-coupled.

We're opting for an AC-coupled BESS so we can retrofit storage without touching the PV DC strings.|AC coupling adds an extra conversion step, so we modeled a 1–3% round-trip efficiency penalty versus DC-coupled.|The microgrid will use AC-coupled solar, wind, and storage to simplify islanding and coordination.


Accelerated Depreciation (MACRS)

A U.S. tax depreciation schedule (Modified Accelerated Cost Recovery System) that allows front-loaded depreciation of eligible energy assets like solar, improving project economics by reducing taxable income in early years.

Our base case uses 5-year MACRS with bonus depreciation to enhance after-tax cash flows.|Without MACRS, the tax equity yield would fall below target.|We modeled MACRS timing to align with the PPA COD for optimal tax benefits.


Ancillary Services

Grid support services such as frequency regulation, spinning/non-spinning reserves, voltage/reactive power support, and black start that maintain reliability and power quality. Storage and advanced inverters commonly provide them.

The BESS will bid into frequency regulation and spinning reserves for ancillary revenue.|We sized the inverter to provide reactive power support as an ancillary service.|The project’s revenue stack includes energy arbitrage plus ancillary services in CAISO.


Balance of System (BOS)

All components and costs of a solar system excluding the PV modules themselves—includes inverters, racking, wiring, combiner boxes, site work, and installation labor. Often split into electrical and structural BOS.

By standardizing skids, we cut BOS costs by 8%.|As module prices fall, BOS becomes a larger share of total CapEx.|BOS scope includes racking, cabling, combiner boxes, trenching, and labor.


Battery Energy Storage System (BESS)

An integrated storage solution including battery cells (e.g., LFP), battery management system (BMS), power conversion system (PCS/inverters), enclosures, HVAC, fire suppression, and control software for charge/discharge management.

The 100 MW/400 MWh BESS will provide peak shaving and capacity.|We specified a 2-hour BESS coupled with PV for TOU arbitrage.|BESS O&M includes HVAC maintenance, firmware updates, and capacity testing.


Bifacial Module

A PV module that captures light on both front and rear sides, increasing energy yield based on rear irradiance from ground reflectance (albedo) and diffuse light. Performance depends on mounting height, spacing, and site albedo.

With high-albedo gravel, we expect a 6–10% bifacial gain.|Tracker height and row spacing were optimized for bifacial performance.|The EPC will conduct a bifaciality factor test on delivered modules.


Capacity Factor

The ratio of actual energy produced over a period to the energy that would have been produced if the plant ran at nameplate capacity continuously. Indicates utilization and resource quality.

The site’s expected capacity factor is 27% with single-axis trackers.|Increasing ILR can raise the effective capacity factor.|We benchmarked capacity factors across ISOs to compare resource quality.


Capital Expenditure (CapEx)

Upfront costs to build and commission a project or product—modules, inverters, BOS, construction, interconnection, development fees, owner’s costs, and contingency.

Module prices dropped, but interconnection CapEx increased due to upgrades.|Our CapEx includes owner’s costs and contingency at 5%.|We split CapEx into module, BOS, EPC margin, and interconnection buckets.


Community Solar

A shared solar project where multiple subscribers (residential, C&I, municipal) receive bill credits for their share of the project’s output, enabling participation without on-site installations.

The project will be a 5 MW community solar farm with residential subscribers.|We’ll use consolidated billing to simplify community solar collections.|Churn assumptions are critical in the community solar revenue model.


Demand Response (DR)

Programs where customers reduce or shift electricity usage during peak periods in response to utility signals or market prices. Often automated via building or energy management systems.

Our EMS will curtail HVAC load to participate in utility DR events.|The battery pre-charges so we can respond to DR calls without impacting operations.|DR revenue helps offset demand charges in summer months.


Degradation Rate

The annual decline in PV module or system performance due to material aging and environmental stress. Typically around 0.2–0.8% per year depending on technology and conditions.

We assumed 0.5% annual module degradation for the P50 case.|Year 1 light-induced degradation was incorporated in the energy model.|Performance warranty covers degradation beyond the guaranteed curve.


Energy Payback Time (EPBT)

The time a system needs to generate the amount of energy that was consumed in its manufacture, transport, and installation. Shorter EPBT indicates better embodied-energy performance.

The EPBT for this PV technology is under two years in high-irradiance regions.|Thin-film modules show favorable EPBT in some climates.|EPBT is a key metric in lifecycle sustainability reporting.


Engineering, Procurement, and Construction (EPC)

A delivery model where a contractor designs (engineers), procures equipment, and constructs the project, often under a fixed-price, date-certain contract with performance guarantees.

We’ll issue an EPC RFP with a turnkey scope and performance guarantees.|The EPC will manage soil remediation and pile testing prior to construction.|EPC wrap includes schedule liquidated damages and availability guarantees.


Feed-in Tariff (FiT)

A policy mechanism guaranteeing a fixed purchase price for renewable electricity fed into the grid over a long term, providing revenue certainty to spur investment.

Under the FiT, all exported kWh earn a fixed price for 20 years.|The FiT rate degresses quarterly to track cost declines.|We compared FiT eligibility versus self-consumption economics.


Front-of-the-Meter (FTM)

Resources connected on the utility side of the meter, participating in wholesale markets or utility programs, as opposed to behind-the-meter assets serving on-site load.

This is an FTM solar-plus-storage asset selling into the wholesale market.|FTM projects face interconnection queues and deliver ancillary services.|We differentiated FTM from behind-the-meter economics in our analysis.


Green Hydrogen

Hydrogen produced via electrolysis powered by renewable electricity (e.g., solar, wind), resulting in near-zero direct emissions. Used for industry, transport, and seasonal storage.

The electrolyzer will run on curtailment to produce green hydrogen.|We’re targeting an LCOH below $3/kg with high-capacity-factor renewables.|The offtake MOU covers green H2 for industrial heat displacement.


Grid Parity

The point at which the cost of renewable electricity equals or undercuts conventional grid electricity prices, making it competitive without subsidies.

Rooftop PV hit grid parity under current TOU rates.|We modeled parity versus wholesale prices for the utility-scale plant.|Battery adders can accelerate parity in high-peak markets.


High-Voltage Direct Current (HVDC)

A transmission technology using direct current at high voltages for efficient long-distance power transfer and interconnection of asynchronous grids; often used for remote renewables.

The offshore wind export cable uses HVDC to reduce losses.|HVDC enables long-distance transmission from high-resource regions.|Converter stations add CapEx but lower line losses over distance.


Hybrid Inverter

An inverter that can interface with both PV and batteries, enabling charge/discharge control, backup operation, and grid-support features within a single power electronics platform.

We chose hybrid inverters to manage PV and battery through one device.|Hybrid inverters enable backup power during outages in island mode.|The UL 1741-listed hybrid inverter supports advanced grid functions.


Inverter Load Ratio (ILR)

The DC-to-AC ratio (PV array nameplate power divided by inverter AC capacity). Also called DC/AC ratio; affects clipping, yield, and cost optimization.

With a 1.35 ILR, clipping increases slightly but boosts annual kWh.|Higher ILR improves morning/evening output and capacity value.|We tested ILR sensitivity from 1.2 to 1.5 in the energy model.


Investment Tax Credit (ITC)

A U.S. federal credit against tax liability based on a percentage of eligible project costs. Current policy frameworks allow adders (e.g., domestic content, energy communities) subject to compliance rules.

The project claims a 30% ITC with applicable adders.|Transferability lets us monetize the ITC without a traditional tax equity investor.|We modeled ITC step-up and recapture risk in the financing case.


Junction Box (J-Box)

An enclosure on the back of a PV module containing bypass diodes and connection terminals, providing cable egress and protecting against environmental exposure.

The module J-box houses bypass diodes and the cable leads.|Inspect J-box potting quality to avoid moisture ingress.|A failed J-box can trigger hot spots and string outages.


Kilowatt-peak (kWp)

The rated DC power output of a PV array under standard test conditions (STC). Used to describe system size and to set DC/AC ratios.

The 500 kWp rooftop system is sized to offset 60% of annual load.|Module nameplate at STC is 550 Wp, so the array totals 3,300 kWp.|Design ILR uses DC kWp versus AC kW inverter capacity.


Levelized Cost of Energy (LCOE)

A lifecycle cost metric: present value of total costs divided by total energy produced over the asset’s lifetime. Enables apples-to-apples comparisons across technologies.

Our LCOE estimate is $32/MWh for the solar farm.|Lower WACC and higher ILR both help reduce LCOE.|We compared LCOE to PPA strike prices and merchant curves.


Lithium Iron Phosphate (LFP)

A lithium-ion battery chemistry valued for thermal stability, long cycle life, and cost effectiveness. Common in stationary storage; typically lower energy density than NMC.

We selected LFP cells for safety and cycle life at the expense of energy density.|LFP thermal runaway risk is lower than NMC in our hazard analysis.|The LFP pack warranty guarantees 70% capacity at year 10.


Maximum Power Point Tracking (MPPT)

Algorithms and hardware that continuously adjust voltage/current to operate PV modules at their maximum power point under changing irradiance and temperature.

The inverter’s MPPT windows must match the string voltage at temperature extremes.|MLPE can enable module-level MPPT under partial shading.|Efficient MPPT improves yield, especially on variable irradiance days.


Module-Level Power Electronics (MLPE)

Electronics installed at the module (e.g., optimizers or microinverters) to perform MPPT, monitoring, rapid shutdown, and sometimes conversion to AC at the module.

We used optimizers to meet rapid shutdown and boost yield on complex roofs.|MLPE increases CapEx but can improve energy harvest and monitoring granularity.|Microinverters are a form of MLPE with AC output at each module.


Net Energy Metering (NEM)

A policy allowing customers to offset consumption with on-site generation by exporting excess energy to the grid, often receiving bill credits; rules vary by jurisdiction and are evolving to net billing.

Under NEM, exported kWh offset imports at retail rates.|NEM 3.0 shifted to net billing with time-varying export credits.|Storage improves economics as NEM credits decline.


Non-Wires Alternatives (NWA)

Distributed solutions (DERs, efficiency, DR, storage) that defer or replace traditional grid infrastructure upgrades, often procured through competitive solicitations.

The utility is procuring NWA solutions to defer a substation upgrade.|A portfolio of PV, storage, and DR can serve as an NWA.|We quantified locational value to compete in the NWA solicitation.


Offtaker

The buyer of energy or attributes from a project (e.g., utility, corporate, municipal). Offtaker creditworthiness and contract terms drive financeability.

The Fortune 500 offtaker signed a 15-year virtual PPA.|We evaluated offtaker credit risk and termination rights.|Municipal offtakers may require specific contract forms.


Operations and Maintenance (O&M)

Activities to operate and sustain asset performance: monitoring, preventive maintenance, corrective repairs, vegetation control, cleaning, and performance analytics.

Proactive O&M reduced truck rolls and inverter downtime.|Annual O&M includes vegetation management and IV-curve tracing.|The O&M contract has availability guarantees and response SLAs.


Photovoltaic (PV)

Technology that converts sunlight directly into electricity using semiconductor materials. Industry shorthand for solar electric systems and components.

The PV array uses monocrystalline PERC modules on trackers.|PV output is forecast using TMY data and loss factors.|We compared PV to solar thermal for process heat needs.


Power Purchase Agreement (PPA)

A long-term contract to sell and buy electricity, specifying price, term, delivery point, and obligations. Structures include physical and virtual PPAs, pay-as-produced, and shaped products.

The offtaker agreed to a 20-year fixed-price PPA with a 1% escalator.|We considered a proxy generation PPA to handle curtailment risk.|PPA codifies delivery terms, pricing, and performance guarantees.


Production Tax Credit (PTC)

A per-kWh tax credit for electricity generated from qualifying resources over a defined period. Policy updates allow certain solar projects to elect PTC instead of ITC, depending on qualifications.

We compared ITC versus PTC election for the solar project under current policy.|Higher capacity factor favored the PTC in our case.|Revenue modeling includes PTC inflation adjustments where applicable.


Qualifying Facility (QF)

A generator that meets criteria under the U.S. PURPA law, gaining rights to sell power at avoided cost and streamlined interconnection, subject to size and fuel requirements.

The project seeks QF certification to sell under PURPA avoided cost rates.|We filed the FERC Form 556 to register as a QF.|QF status can improve interconnection priority in some cases.


Quality Assurance/Quality Control (QA/QC)

Processes to ensure components and installations meet specified standards—factory audits, testing, inspections, and commissioning procedures to maintain reliability and safety.

Our QA/QC plan includes factory witness tests and receipt inspections.|We perform EL imaging to detect cell cracks for QC.|QA/QC reduces early-life failures and warranty claims.


Reactive Power

Non-working power (measured in VARs) necessary to maintain voltage and support AC power systems. Advanced inverters can inject or absorb reactive power.

Inverters provide reactive power to maintain feeder voltage.|The interconnection agreement requires a ±0.95 power factor range.|We sized inverters for reactive capability during peak solar output.


Renewable Energy Certificate (REC)

Tradable certificates representing the renewable attributes of 1 MWh of generation. Used for compliance with RPS or voluntary claims; distinct from energy itself.

We’ll unbundle RECs and sell them into the voluntary market.|The PPA is energy-only; RECs are retained by the offtaker.|Tracking registries verify REC creation and retirement.


Renewable Portfolio Standard (RPS)

A policy requiring a certain percentage of electricity sales to come from renewable sources, often with carve-outs (e.g., solar) and a REC-based compliance mechanism.

The state’s RPS hits 60% by 2030, driving utility procurement.|SREC multipliers help meet solar carve-outs within the RPS.|We track RPS eligibility to value project RECs.


Single-Axis Tracker (SAT)

A mounting system that rotates PV modules around one axis to follow the sun’s path, boosting energy yield compared to fixed-tilt systems.

SATs increased yield by ~15% versus fixed-tilt at this latitude.|Tracker controls include backtracking to reduce row-to-row shading.|We analyzed O&M impacts of SAT gearboxes and motors.


Solar-plus-Storage

Co-located or hybrid deployment of PV and battery storage to increase value via time-shifting, capacity provision, and grid services.

The solar-plus-storage plant will time-shift energy into evening peaks.|Co-located solar-plus-storage optimizes interconnection capacity.|Revenue stacking includes energy, capacity, and ancillary services.


SREC (Solar Renewable Energy Certificate)

A REC specifically representing 1 MWh of solar generation, used in jurisdictions with solar carve-outs. Often trades at distinct prices from generic RECs.

The project sells SRECs into a state solar carve-out market.|SREC prices affect PPA negotiation in compliance states.|We modeled SREC strip sales to de-risk revenue.


Tax Equity

Financing structures where investors with tax appetite monetize credits and depreciation in exchange for project interests. Common structures include partnership flips and sale-leasebacks.

We’re pursuing a partnership flip structure with a tax equity investor.|Transferability offers an alternative to traditional tax equity.|Tax equity diligence includes ITC/PTC qualification and MACRS.


Time-of-Use (TOU) Rates

Electricity rates that vary by time-of-day and season to reflect system costs. Influence solar and storage dispatch and economics.

Storage charges off-peak and discharges during high TOU periods.|We sized the battery to hedge the evening TOU super-peak.|NEM reforms shifted export credits to TOU schedules.


UL 1741 (SA/SB)

A UL certification standard for inverters and interconnection equipment. Supplement A (SA) addressed advanced grid support; Supplement B (SB) aligns with IEEE 1547-2018 requirements.

The inverter is certified to UL 1741 SB for IEEE 1547-2018 functions.|Rule 21 requires UL 1741 SA capabilities for grid support.|Certification covers ride-through and voltage/reactive power modes.


Utility-Scale Solar

Large PV plants interconnected at high voltage, selling into wholesale markets or under utility PPAs. Typically tens to hundreds of MW or more.

Utility-scale solar competes at sub-$30/MWh in some regions.|Interconnection and transmission constraints dominate utility-scale timelines.|We’re bidding utility-scale solar into the ISO capacity auction.


Value of Solar (VOS) Tariff

A rate design that pays solar exports based on quantified avoided costs and benefits, often including energy, capacity, transmission/distribution, and emissions values.

The VOS tariff compensates exports based on avoided costs.|We calculated VOS components: energy, capacity, T&D, and environmental.|VOS may replace net metering in the proposed policy.


Virtual Power Plant (VPP)

A networked aggregation of distributed energy resources (PV, batteries, DR, EVs) coordinated via software to provide grid services as if it were a single power plant.

The VPP aggregates home batteries to bid into frequency regulation.|Enrollment in the VPP provides bill credits during DR events.|We’re integrating PV inverters and EV chargers into the VPP platform.


Weighted Average Cost of Capital (WACC)

The blended cost of a project’s capital, weighting debt and equity costs by their proportions. Used as the discount rate in valuation and LCOE calculations.

Lowering WACC by 100 bps reduces LCOE materially.|Our WACC assumption reflects tax equity, debt, and sponsor equity costs.|Sensitivity shows WACC dominates valuation uncertainty.


Wheeling Charge

A fee paid for transmitting electricity across a third party’s transmission or distribution network from a generator to a load, affecting delivered cost.

The offtaker pays a wheeling charge to move energy across a neighboring utility’s lines.|Wheeling costs affect the economics of remote PPA delivery.|We negotiated reduced wheeling tariffs for the corporate VPP.


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