An electric vehicle parked in a driveway holds more usable energy than most residential battery systems. A 65 kWh EV battery stores nearly five times the capacity of a Tesla Powerwall, and with vehicle-to-grid (V2G) technology, that energy can flow back to the home, power critical loads, or export to the grid during peak demand. For solar installers, this shifts the design brief in fundamental ways: V2G solar design requires bidirectional inverters, revised array sizing calculations, smart metering, and utility interconnection agreements that standard grid-tied PV installations never require. This guide covers every dimension of that shift — from charger architecture to revenue modeling — so you can design and sell V2G-ready solar systems with confidence.
TL;DR — V2G Solar Design
V2G turns an EV battery into a bidirectional energy asset. For solar installers, it means upgrading to hybrid inverters, resizing arrays to cover EV charging loads, implementing export controls, and securing utility interconnection for bidirectional flow. University of Delaware V2G participants earned ~$1,200/year per vehicle from grid services, and the global V2G market is projected to reach $54 billion by 2035.
What this guide covers:
- How bidirectional charging works — AC vs. DC architectures
- The difference between V2G, V2H, and V2L, and why it matters for design
- How V2G changes inverter selection, array sizing, and grid connection
- Which EVs and chargers support V2G in 2026
- The financial case for V2G-ready solar installations
- Regulatory and interconnection requirements by region
- How solar design software must evolve for bidirectional systems
What V2G Actually Means for Solar Installers
The conventional solar-plus-battery design has one job: generate electricity, store what the household cannot use immediately, and draw from storage when the sun is not shining. Energy flows in one direction. A V2G-capable solar system treats the EV battery as a dispatchable asset that can absorb generation, hold it, and release it on demand to the home or the grid.
The EV battery has properties no stationary battery does. It is mobile, so its availability depends on driving schedules. Its state of charge on arrival home varies with daily distance driven. And unlike a home battery that sits at a fixed location and is always connected, the EV is a moving target for energy dispatch logic.
Three new design variables emerge immediately:
Variable storage availability. The EV is not always home. A car used for commuting is typically away 8–10 hours per day. Any energy management logic that depends on the EV must account for periods when the storage asset is simply absent.
Dynamic state of charge on arrival. A home battery begins each day at a predictable charge level. An EV does not. If the car returns home with 15% state of charge after a long day, there is no usable V2G capacity until solar or grid power recharges it above the V2G threshold — typically 30–40% for most systems.
Utility coordination. In V2G, the vehicle discharges to the grid, making it a generator in the eyes of the utility. That requires an interconnection agreement, a certified bidirectional inverter, and in many cases a separate smart meter to measure exported energy. Standard solar G98/G99 notifications in the UK or NEM interconnection in the US do not automatically cover V2G.
The practical implication is that V2G solar design requires a system-level approach that standard PV design checklists were not built to handle. Getting it right means rethinking inverter selection, array sizing, metering, and the client conversation around what V2G actually delivers.
The opportunity is real. An average EV battery at 65 kWh stores roughly 5 times the energy of a Powerwall 3 at 13.5 kWh. If a homeowner drives 40 km per day and consumes 7 kWh in the process, the remaining 58 kWh is potential V2G capacity — subject to vehicle manufacturer limits on discharge depth. Even using half of that (29 kWh) as dispatchable storage changes the economic case for solar dramatically. The system shifts from offsetting imports to actively generating grid revenue during peak hours.
Key Takeaway
V2G treats the EV battery as a dynamic, dispatchable storage asset. For solar system design, the EV introduces variable availability, variable state of charge, and utility interconnection requirements that do not apply to stationary battery installations.
Bidirectional Charging Architecture: AC vs. DC
A standard EV charger is a managed switch. Alternating current from the grid passes through the EVSE (electric vehicle supply equipment), converts to direct current inside the vehicle’s onboard charger (OBC), and flows into the battery. Power moves in one direction only: from wall to car.
Bidirectional charging reverses that flow. DC from the EV battery converts to AC and flows back to the home or grid. The design question is where that conversion happens.
AC Bidirectional Charging
In AC bidirectional systems, power conversion — both AC-to-DC when charging and DC-to-AC when discharging — happens inside the vehicle using the onboard charger. The external EVSE hardware is simpler and less expensive because all the power electronics live in the car.
The limitation is the OBC’s power rating. Most onboard chargers handle 7.4 kW or less. That puts a ceiling on the discharge rate: a V2H or V2G system using AC bidirectional charging cannot push more than the OBC’s rated output, regardless of battery size. For a 65 kWh battery discharging at 7.4 kW, that is a maximum of roughly 8.8 hours to fully discharge — acceptable for overnight V2G dispatch, but limiting for rapid grid response events.
AC bidirectional has been the dominant V2G architecture to date, largely because it is simpler to retrofit and cheaper to manufacture. Most CHAdeMO-based V2G systems use AC bidirectional logic.
DC Bidirectional Charging
In DC bidirectional systems, the power conversion happens in the external charger, not the vehicle. The charger handles both AC-to-DC (charging) and DC-to-AC (discharging) with dedicated power electronics. The vehicle’s OBC is bypassed entirely during DC charging and discharging.
This architecture allows significantly higher power rates — typically 11–22 kW for residential units. The SolarEdge V2X charger operates at up to 11.5 kW DC bidirectional. The trade-off is cost and complexity. DC bidirectional chargers carry more sophisticated power electronics and typically cost 2–3 times more than AC bidirectional equivalents. They also require the vehicle to support DC bidirectional via ISO 15118-20, a protocol still being rolled out across new model lines in 2025–2026.
DC-Coupled vs. AC-Coupled with Solar
When combining V2G with a solar system, the coupling architecture determines efficiency and complexity.
In a DC-coupled system, solar panels, battery or V2G charger, and inverter all share the same DC bus. Power flows from panels directly to the DC bus, and the inverter handles AC conversion. The EV charges and discharges via the DC bus, avoiding an AC-to-DC-to-AC conversion cycle. Round-trip efficiency in DC-coupled systems typically reaches 94–96%.
In an AC-coupled system, the solar inverter converts panel output to AC and puts it on the home’s AC bus. The bidirectional EV charger also sits on the AC bus. When charging the EV from solar, the power goes DC (panels) → AC (inverter) → DC (charger). Round-trip efficiency drops to roughly 88–91%. Higher losses, but works with any existing solar installation and any AC bidirectional charger.
For new installations, DC-coupled is the better design choice. For retrofits where an existing solar system is already in place, AC-coupled is often the only practical option.
| Feature | AC Bidirectional | DC Bidirectional |
|---|---|---|
| Conversion location | Inside vehicle (OBC) | External charger |
| Max power (typical) | 3.6–7.4 kW | 11–22 kW |
| Installation cost | Lower | Higher |
| Solar coupling | AC-coupled | DC-coupled possible |
| Vehicle compatibility | CHAdeMO, some CCS2 | CCS2 + ISO 15118-20 |
| Round-trip efficiency | 88–91% | 94–96% |
| Example equipment | Wallbox Quasar 2 | SolarEdge V2X |
ISO 15118: The Protocol That Makes V2G Work
ISO 15118 defines how the EV and charger communicate. It covers authentication, power scheduling, and in the -20 variant, DC bidirectional power flow parameters. The EV reports its current state of charge, maximum charge and discharge power, and available energy to the charger. The charger — and connected home energy management system — uses this data to schedule charging and discharging.
Without ISO 15118, a bidirectional charger cannot know how much energy the EV can safely discharge. That is why vehicle-charger compatibility depends on both the connector type (CCS2 or CHAdeMO) and software protocol support — not just the hardware plug.
V2G, V2H, and V2L: Design Implications for Each Mode
The terms V2G, V2H, and V2L are often used interchangeably in marketing materials. They describe three distinct operating modes with very different design implications.
V2L: Vehicle to Load
V2L is the simplest form of bidirectional EV use. The vehicle powers appliances or equipment via an adapter plugged into a standard AC socket on the car or via a dedicated outlet on the charge port. No home wiring integration, no utility agreement, no inverter coordination.
V2L output is limited — typically 2.4–3.6 kW continuous (Hyundai IONIQ 5, Kia EV6) up to 9.6 kW for trucks like the Ford F-150 Lightning. It is useful for job sites, outdoor events, and emergency loads during power outages, but it has no place in a grid-tied solar system design. V2L does not interact with the solar inverter, the home panel, or the meter.
V2H: Vehicle to Home
Vehicle-to-home (V2H) connects the EV battery to the home’s internal wiring, powering the house when the grid is down or during peak tariff periods. It requires an automatic transfer switch (ATS) or a specialized V2H gateway that disconnects the home from the grid before activating EV discharge.
The isolation requirement means V2H typically operates in island mode — the home is electrically separated from the grid during EV discharge. This eliminates the need for a utility interconnection agreement in most markets, simplifying the regulatory path considerably. For solar system design, V2H adds a layer of complexity: the solar inverter must also enter island mode and synchronize with the EV’s AC output when the grid is disconnected. Not all hybrid inverters support this behavior out of the box.
V2G: Vehicle to Grid
V2G is the full bidirectional mode. The EV discharges to the utility grid, generating revenue from grid services — frequency regulation, demand response, or time-of-use arbitrage. This requires:
- A utility interconnection agreement for bidirectional export
- A grid-compliant bidirectional inverter certified for export
- A smart meter that measures and timestamps bidirectional flows
- A home energy management system (HEMS) to schedule dispatch
V2G is the only mode with direct revenue potential from grid services. It is also the most complex, the most expensive to install, and the least uniformly supported by utilities as of 2026. Most operational V2G programs remain in pilot phase.
| Mode | Grid Export | Utility Agreement | Regulatory Complexity | Revenue Potential |
|---|---|---|---|---|
| V2L | No | Not required | Minimal | None |
| V2H | No | Not required | Low | Indirect (bill savings) |
| V2G | Yes | Required | High | Direct (grid services) |
The practical starting point for most installers in 2026: design for V2H capability with hardware that can be upgraded to V2G. This future-proofs the installation and avoids regulatory delays while delivering immediate backup power value to the client.
How V2G Rewrites Solar System Design Rules
This is where V2G has the most direct impact on daily design work. Four areas change fundamentally.
Inverter Selection and Sizing
A standard string inverter is unidirectional. DC from the panels converts to AC and flows to the home or grid. It cannot accept energy from the AC side and push it back to DC, and it cannot discharge an EV battery.
V2G solar systems require a hybrid inverter — an inverter with a bidirectional DC bus and typically a battery port. The hybrid inverter manages power flow among three sources: solar panels (DC), battery or EV charger (DC), and the grid (AC). When the EV is discharging, the hybrid inverter routes that energy to AC loads and, if export is permitted, to the grid.
V2G-ready hybrid inverter systems available in 2026 include the SolarEdge Home Hub paired with the SolarEdge V2X charger (DC-coupled, CCS2), the Enphase IQ EV Charger with Enphase Ensemble energy management (AC-coupled), and SMA’s Sunny Home Manager integrated with bidirectional storage. Each ecosystem locks in specific V2G charger compatibility, so the inverter and charger decision must be made together.
Combined inverter capacity is a constraint installers frequently overlook. Many distribution networks cap the total inverter capacity per phase for small embedded generation. SA Power Networks in Australia limits this to 10 kVA per phase. A 5 kW solar inverter plus a 10 kW V2G charger totals 15 kVA — that combination triggers a medium embedded generation application, which requires DNO approval and may take weeks or months. Check your local network’s technical standard before specifying equipment.
The anti-islanding paradox is the other inverter challenge. Solar inverters must shut down when the grid fails — this is anti-islanding protection, required by law in most markets to protect line workers. But V2H and V2G island mode requires the inverter to continue operating when the grid is absent. These two requirements seem contradictory. The resolution is a smart inverter with grid-forming firmware: it detects the difference between a controlled grid disconnection (intentional island) and an uncontrolled grid fault, and responds differently. Not all hybrid inverters on the market support this dual behavior. Confirm grid-forming capability explicitly before specifying any inverter for a V2G system.
Pro Tip
Check the inverter datasheet for “grid-forming” or “off-grid capable” functionality. A hybrid inverter that can only operate in grid-following mode will not support V2H island mode or seamless V2G switchover during grid events.
Solar Array Sizing with V2G Loads
Standard PV array sizing uses one equation: annual household consumption divided by specific yield for the location. V2G adds two more loads to that calculation: EV charging demand and V2G discharge reserve.
EV charging load. An EV driven 40 km per day at 6 km/kWh consumes approximately 7 kWh of battery per day. At 100 km per day, that rises to roughly 17 kWh. If the client wants to charge the EV entirely from solar — the only configuration that makes environmental sense for V2G — the array must cover that load in addition to the household.
In central Europe with ~1,100 kWh/kWp annual yield, covering 7 kWh/day of additional load requires roughly 2.3 kWp of extra solar capacity. Covering 17 kWh/day requires approximately 5.6 kWp. These are material additions to what would otherwise be a standard residential system size.
V2G discharge reserve. If the system is designed for V2G dispatch in the evening peak (typically 17:00–21:00), the EV must arrive home with enough charge to fulfill both the V2G dispatch target and retain a safe minimum state of charge — typically 20% for most systems. The solar array must be sized to refill the battery after each V2G discharge event, on top of covering household loads.
A worked example: client drives 50 km per day (8 kWh consumed), V2G dispatch target is 15 kWh per evening, minimum SoC reserve is 20% (13 kWh on a 65 kWh battery). Total daily charge required: 8 kWh (driving) + 15 kWh (V2G dispatch) = 23 kWh. Household load: 12 kWh/day. Total solar output required: 35 kWh/day. At 1,100 kWh/kWp annual yield (~3 kWh/kWp per day average), that requires approximately 11.7 kWp — nearly double what a standard household-only design would specify.
Orientation and tilt. In a V2G-optimized design, the timing of solar generation matters as much as total annual yield. West-facing panels generate more output in the afternoon (14:00–18:00), which aligns with the window when the EV is home and being charged before the V2G dispatch window opens. A split array — south for maximum annual yield, west for afternoon peak generation — often outperforms a pure-south array in a V2G context when modeled against TOU tariff structures.
Key Takeaway
V2G array sizing must account for EV charging load and daily V2G dispatch reserve — not just household consumption. For a typical European client with a 50 km daily commute and 15 kWh V2G target, the required array size can be nearly double a standard residential system.
System Coupling Strategy
Three practical configurations exist for solar combined with V2G:
DC-coupled (new build, preferred). Solar panels connect to a shared DC bus. The hybrid inverter manages the bus and handles AC conversion. The V2G charger connects to the DC bus directly, charging and discharging the EV battery without any AC conversion overhead. Efficiency: 94–96% round-trip. Requires a DC-coupled V2G charger (SolarEdge V2X, Red Earth Boomerang). Best for new-build systems where the full architecture can be specified from scratch.
AC-coupled (retrofit, flexible). The existing solar inverter converts panel output to AC. The bidirectional EV charger connects to the home’s AC bus. Each power conversion adds losses: solar DC to AC (3–5% loss), then AC to DC into the EV (3–5% loss), then DC to AC on discharge (3–5% loss). Round-trip efficiency in AC-coupled V2G: 85–90%. Higher losses, but works with any existing solar installation and any AC bidirectional charger. Best for retrofits.
Hybrid AC+DC. Solar and a stationary battery share the DC bus via a hybrid inverter. The V2G charger is AC-coupled on the AC side. This is the most common configuration in practice right now — it allows a separate stationary battery for islanding and fast response alongside the EV for bulk storage and V2G. Efficiency falls between the two architectures above. See the commercial battery storage sizing guide for sizing the stationary battery component in a hybrid setup.
For most residential V2G installs in 2026, the hybrid AC+DC architecture is the pragmatic choice — it works with a broad range of EVs and chargers and does not require the client to have a DC-bidirectional-capable vehicle.
Grid Connection and Export Controls
V2G changes the site’s relationship with the grid connection. A solar-only system exports during the day. A V2G system can export during the day (solar) and during the evening (EV discharge). The combined peak export of solar plus V2G can exceed the agreed export limit if not properly controlled.
CT clamp at the grid connection point. A current transformer sensor mounted at the utility meter monitors real-time import and export. The HEMS reads this data continuously and adjusts EV charge and discharge rates to prevent the combined export from exceeding the agreed connection limit. This is the same function used in solar export-limit control setups, but applied to bidirectional flows in both directions.
Smart meter. A standard accumulation meter cannot distinguish between imported and exported energy in the same interval. A smart meter with interval data recording — typically 30-minute or 5-minute intervals — is required for any V2G installation. The meter timestamps import and export separately, enabling TOU billing and V2G revenue tracking. In the UK, SMETS2 meters support this. In Australia, a Type 4 meter is required for embedded generators including V2G.
HEMS dispatch logic. The home energy management system is the operational brain of a V2G solar installation. It monitors solar generation, EV state of charge, household load, grid prices, and any utility dispatch signals, then decides in real time whether the EV should charge (absorb solar surplus), hold (preserve V2G capacity), or discharge (export during peak). Without a HEMS, V2G is uncontrolled — the EV charges and discharges without optimization, undermining both the financial case and grid stability compliance.
Compatible EVs and Chargers in 2026
The V2G-compatible vehicle market has expanded materially in 2025–2026, with CCS2 plus ISO 15118-20 replacing CHAdeMO as the dominant standard for new installations.
| Make and Model | Mode | Connector | Max Export | Status |
|---|---|---|---|---|
| Nissan Leaf (e+) | V2G/V2H | CHAdeMO | 6 kW | Available |
| Kia EV9 | V2G | CCS2 | 3.6 kW | Pilot (Netherlands) |
| Hyundai IONIQ 9 | V2G | CCS2 | 3.6 kW | Pilot (Netherlands) |
| BMW iX3 (2026) | V2G | CCS2 | TBC | Launch spring 2026 (DE) |
| Ford F-150 Lightning | V2H/V2L | Proprietary | 9.6 kW V2L | Available (US) |
| Volkswagen ID.4 / ID.7 | V2G | CCS2 | TBC | Q4 2026 (EU, via Elli) |
| BYD Atto 3 | V2L | Adapter | 2.4 kW | Available |
CHAdeMO is declining. Nissan’s next-generation EVs will shift to CCS2, and no major new CHAdeMO-only V2G EVs have been announced. CCS2 with ISO 15118-20 is the standard to design around for any new V2G installation today.
NACS Note
In North America, the NACS connector (formerly Tesla’s proprietary standard) is gaining adoption across Ford, GM, and Rivian. V2G-capable NACS hardware is still emerging in 2026. Confirm charger compatibility with NACS-equipped vehicles before specifying equipment for US clients.
V2G-capable charger and inverter systems:
| Product | Type | Max Power | Solar Integration | Connector |
|---|---|---|---|---|
| Wallbox Quasar 2 | AC bidirectional | 7.4 kW | AC-coupled | CHAdeMO |
| SolarEdge V2X | DC-coupled | 11.5 kW | DC bus (Home Hub) | CCS2 |
| Enphase Bidirectional EV Charger | AC bidirectional | 11.5 kW | AC-coupled (IQ system) | CCS2 |
| Red Earth Boomerang | DC bidirectional | 10 kW | DC-coupled | CHAdeMO |
SolarEdge’s V2X charger represents the most integrated DC-coupled V2G solution for installers working within the SolarEdge ecosystem. For Enphase system installers, the bidirectional EV charger integrates natively with the Enphase HEMS and Ensemble energy management platform.
Pro Tip
Confirm vehicle compatibility with the specific charger BEFORE specifying equipment. Charger-vehicle combinations must match on connector type, communication protocol (CHAdeMO or ISO 15118), and software version. A mismatch means the vehicle charges one-way only — no bidirectional capability regardless of the charger spec sheet.
The Financial Case for V2G Solar
V2G changes the financial model of a solar installation in two ways: it adds a revenue stream through grid services and it replaces or supplements stationary battery storage.
Equipment Cost Premium
A standard Level 2 home EV charger costs $500–$1,500 installed. A bidirectional V2G charger costs $6,000–$10,000 installed — roughly 4–6 times more. That premium must be justified in the financial proposal.
The stationary battery comparison is the right frame for clients already considering storage. A 10 kWh home battery in the UK costs approximately £4,000–£7,000 installed. The V2G charger premium above a standard L2 is similar: £4,000–£6,000. But the V2G charger gives access to 20–50 kWh of dynamic EV storage — not a fixed 10 kWh battery. For clients who already need an EV charger, the relevant question is not “is V2G worth £7,500” but “is the £5,000 premium over a standard L2 worth it.”
Revenue Sources
V2G generates revenue through three mechanisms:
Frequency regulation. The EV charges and discharges rapidly in response to grid frequency deviations. University of Delaware’s V2G program generated approximately $1,200 per year per vehicle through this mechanism. This is the highest-value V2G service, but it requires access to a utility or aggregator frequency regulation market.
Time-of-use arbitrage. Charge during off-peak hours at a cheap import rate, discharge during peak hours to avoid expensive imports or receive export premiums. With a 15 kWh daily V2G discharge and a TOU spread of 15p/kWh (a typical UK example), this adds £820/year.
Demand response. The utility pays participants to reduce or shift load during peak grid events. V2G enables demand response by shifting EV charging to off-peak periods and discharging during peak events. Revenue: £200–£500/year depending on event frequency and program structure.
Payback Calculation
Simple payback on the V2G charger premium over a standard L2 (UK example):
| Item | Value |
|---|---|
| Standard L2 charger (installed) | £1,200 |
| V2G bidirectional charger (installed) | £7,500 |
| V2G premium | £6,300 |
| Frequency regulation revenue | £800/year |
| TOU arbitrage savings | £600/year |
| Total annual benefit | £1,400/year |
| Simple payback | ~4.5 years |
This assumes the client participates in a utility V2G program — which in 2026 is still not universally available. Where no program exists and only TOU arbitrage applies, payback stretches to 8–10 years.
The honest client conversation: V2G economics are strong where utility programs exist (UK, Netherlands, Japan, parts of the US), marginal where only TOU arbitrage is available, and unproven where no V2G market has launched yet.
Use the generation and financial tool to model full ROI scenarios including V2G revenue streams, TOU rate structures, and battery dispatch optimization for specific client projects.
Regulatory and Interconnection Considerations
V2G sits at the intersection of EV regulation, distributed generation rules, and utility interconnection requirements. None of those frameworks were originally written with V2G in mind, and the alignment is still incomplete in most markets as of 2026.
Key Technical Standards
ISO 15118 — The EV-charger communication protocol. Defines power scheduling, authentication, and in the -20 variant, DC bidirectional flow parameters. V2G without ISO 15118 cannot coordinate charge and discharge scheduling between the vehicle and the HEMS.
IEEE 1547-2018 (US) — Defines technical requirements for interconnecting distributed energy resources including bidirectional EV chargers. Covers voltage, frequency, and islanding requirements. Most state interconnection processes reference 1547-2018 or a state-specific equivalent.
AS/NZS 4777.2 (Australia) — Inverter grid-connection standard. Being updated to address bidirectional flows and V2G operation. Current version requires compliant inverters for any grid export, including V2G.
IEC 62898 (Europe/global) — Microgrid technical guidelines, relevant to V2H island mode configurations.
Market-by-Market Status
United Kingdom. Ofgem ran a V2X regulatory sandbox in 2021–2023. Commercial V2G tariffs are now available from suppliers including Octopus Energy (Power-Up) and OVO Energy. G98/G99 notifications are being updated to cover V2G. Confirm with the DNO that the specific V2G charger model is on the approved product list before connecting.
European Union. The EU Alternative Fuels Infrastructure Regulation (AFIR) requires ISO 15118 compliance for new DC chargers from April 2025. V2G export frameworks vary by member state. The Netherlands is the most advanced market, with commercial V2G tariffs available from Eneco and several utilities. Kia and Hyundai launched commercial V2G services for the EV9 and IONIQ 9 in the Netherlands in late 2025.
United States. FERC Order 2222 (2020) opened wholesale ancillary service markets to DER aggregators, including EVs. Implementation varies by ISO/RTO. California, Hawaii, and New York are the most active states for residential V2G pilots. Most other states remain in early exploration.
Australia. AEMO’s Integrated System Plan recognizes EV V2G as a grid resource. SA Power Networks has published technical requirements for bidirectional chargers under its embedded generation framework. Victoria and NSW DNOs are developing equivalent guidelines.
The consistent practical advice across all markets: confirm the local DNO or utility’s specific V2G interconnection requirements before finalizing any design. Requirements vary by network operator within a country, not just by country.
Pro Tip
File the DNO interconnection application early. In markets where V2G approval is separate from the solar notification — which includes most markets — the process takes 4–12 weeks. Build this into project timelines at the sales stage, not at installation.
How Solar Design Software Must Adapt for V2G
Standard solar design software models a unidirectional system: panels generate DC, inverter converts to AC, household consumes, surplus exports. The model assumes energy flows in one direction. V2G breaks that assumption entirely.
A V2G solar system has energy flowing in multiple directions across the day. Solar exports during the morning. The EV charges from solar in the afternoon. The EV discharges to the home in the early evening. Export surplus from V2G discharge flows to the grid. The HEMS switches among these states in real time based on prices, generation, and grid signals.
Modeling that system requires inputs and outputs that standard PV design tools were not built to accept.
New Variables V2G Design Software Must Handle
EV availability schedule. How many hours per day is the vehicle connected? Which days per week? A commuter vehicle connected 14 hours per day has very different V2G capacity than a shared household vehicle that is rarely home during solar generation hours.
EV state of charge on arrival. A simple assumption (EV always arrives at 50% SoC) significantly overstates available V2G capacity. Conservative modeling assumes 30% arrival SoC on high-mileage days.
V2G dispatch logic. When does the HEMS decide to discharge? The simplest logic: discharge when grid price exceeds a threshold. More sophisticated: frequency regulation mode with sub-minute intervals. The dispatch logic determines annual V2G revenue, and software must simulate it against historical TOU prices or grid event data.
TOU rate structure. V2G arbitrage depends entirely on the price spread between cheap import periods and expensive export or peak periods. Software must model the specific TOU tariff for the client’s utility.
Combined inverter capacity constraint checking. The software should flag when the specified solar inverter plus V2G charger capacity exceeds the local DNO limit, triggering a warning that a separate interconnection application is required.
Export limit compliance. The software must model the combined peak export (solar generation plus V2G discharge) and confirm it stays within the agreed export limit. If not, it should suggest reducing array size, limiting V2G discharge rate, or applying for a higher export limit.
Battery degradation under V2G cycling. Standard PV+storage software models EV battery degradation at approximately 2–3% per year based on normal charging cycles. V2G adds discharge cycles that can accelerate degradation if SoC is not managed. The software should model V2G cycling effects on battery capacity over the system lifetime.
What a V2G Solar Proposal Must Include
A complete V2G proposal should present:
- Annual V2G revenue projection by service type — frequency regulation, TOU arbitrage, demand response
- Net annual bill impact — import reduction plus export revenue
- Optimal array size for the V2G scenario
- Combined inverter capacity check with DNO limit flagging
- Return on investment including V2G charger premium above standard L2
- 10-year and 25-year cashflow with EV battery degradation modeled
Purpose-built solar design software that integrates V2G modeling is not yet standard across the industry, but it is the direction the market is moving. The generation and financial tool supports TOU modeling and battery dispatch optimization for hybrid solar+storage systems — covering the financial modeling layer of V2G analysis for client proposals.
The evolution of solar software toward V2G awareness is a competitive differentiator. Installers who present a complete V2G financial model — rather than a vague “saves money” claim — will convert more clients.
Shadow analysis and site assessment also take on new significance in a V2G design context: the goal is not just to maximize annual yield but to maximize generation during afternoon hours when the EV is home and charging. West-facing array components and split orientations deserve more attention in V2G system design than in standard solar-only proposals.
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Conclusion
V2G is not a future technology. Pilot programs in the Netherlands, UK, Japan, and the US have demonstrated real grid service revenue. Commercial products from SolarEdge, Enphase, and Wallbox support bidirectional EV charging today. The gap between what is technically possible and what most solar installations deliver is narrowing fast — and the installers who learn V2G design now will serve clients who are already asking about it.
Three concrete actions to take now:
- Specify hybrid inverters for all new residential solar installations, even where the client has no EV yet. The incremental cost is modest and the V2G upgrade path is clear when an EV arrives.
- Build V2G revenue estimates into financial proposals for EV-owning clients — use conservative figures ($800–$1,200/year from grid services, £500–£800 from TOU arbitrage) and present them as contingent on utility program availability in the client’s area.
- Contact your DNO before submitting any V2G interconnection application. Requirements differ by network operator, and in most markets the process is separate from standard solar notification. Build 8–12 weeks into the project timeline for regulatory approval.
The EV sitting in your client’s driveway is already the largest battery asset they own. V2G solar design is how that asset earns its keep.
Frequently Asked Questions
Which EVs support V2G in 2026?
Confirmed V2G-capable vehicles in 2026 include the Nissan Leaf (CHAdeMO), Kia EV9, Hyundai IONIQ 9, and the BMW iX3 launching in Germany with E.ON. Volkswagen has announced a V2G offering through Elli for Q4 2026. Vehicles using CCS2 with ISO 15118-20 protocol support are the growing standard. CHAdeMO is declining and is not the target connector for new V2G installations.
Can I add V2G to an existing solar system?
Yes, but it requires equipment upgrades. You need a bidirectional charger compatible with your EV, a hybrid inverter with V2G capability, and likely a home energy management system. If your existing inverter is unidirectional, it must be replaced or supplemented. Always check combined inverter capacity limits with your DNO before upgrading — the addition of a V2G charger may push your total embedded generation capacity above the threshold for simple notification.
Does V2G degrade my EV battery faster?
The evidence is mixed. A University of Delaware V2G study found no significant additional degradation when discharge depth was controlled. Modern battery management systems in V2G-capable EVs are designed to limit degradation by preventing discharge below 20% state of charge. The risk increases when the vehicle is repeatedly discharged aggressively. For frequency regulation service — which involves frequent small charge and discharge cycles — degradation appears minimal compared to deep-discharge V2G patterns.
How much can I earn from V2G grid services?
University of Delaware participants earned approximately $1,200 per year per EV through frequency regulation services. TOU arbitrage alone typically generates £500–£800 per year in the UK market, based on typical peak/off-peak spreads. Revenue depends on grid service type, local utility programs, vehicle availability, and dispatch management. Most residential V2G programs remain in pilot phase, so commercial revenue models are not yet standardized across markets.
What standards govern V2G installation?
The primary communication standard is ISO 15118, which defines the protocol between EV and charger. The -20 variant covers DC bidirectional operation. Grid-side standards include IEEE 1547-2018 in the US, AS/NZS 4777.2 in Australia, and local DNO grid codes in Europe. In the UK, G98/G99 notifications are being updated specifically for V2G. Confirm your DNO’s bidirectional charger approved product list before specifying equipment.
Do I need a special inverter for V2G with solar?
Yes. A standard string inverter cannot handle bidirectional power flow. V2G solar systems require a hybrid inverter with bidirectional DC bus capability, or a DC-coupled architecture where the bidirectional charger connects directly to the DC bus. Equipment from SolarEdge, Enphase, and SMA includes V2G-ready hybrid inverter options. The inverter must also support grid-forming mode for V2H island operation and meet all local grid code requirements for bidirectional export.
