Solar Design for Townhouses: Shared Roof Rules

Last updated: November 2026

A townhouse roof can look like one continuous surface while belonging to several different legal and electrical arrangements. The roof above a unit may be private, common property or subject to exclusive-use rights. A workable solar layout starts by resolving those boundaries and the route from the array to the approved meter.

This guide compares roof-allocation methods, electrical architectures, approval records and a four-unit illustrative design. It keeps roof rights, modeled generation and utility billing separate so the association can make an informed decision before an installer commits to a layout.

SurgePV publishes this post and sells solar design software.

Who Owns the Roof on a Multi-Story Townhouse

The title, governing documents and local law determine roof rights. Building appearance and the position of a party wall do not establish who can authorize panels, penetrations or access.

Fee-simple townhouse with party walls. A unit owner may own the roof above the unit, while party-wall arrangements, covenants and access rights still constrain alterations. Review the actual documents before concluding that association approval is unnecessary.

Condominium-style townhouse with a common roof. The roof may be common property managed by the association or owners corporation. Ownership of the unit does not automatically grant an unrestricted right to occupy a particular roof section. Identify the approval and use-right arrangement appropriate to the jurisdiction.

Roof with limited common-element or exclusive-use rights. A unit may have exclusive use of a defined section while structural maintenance remains a collective responsibility. Exclusive use and authority to alter the roof are separate questions. Check both before assigning solar capacity.

Ask for the declaration, recorded plan, relevant leases, bylaws and existing roof or access agreements. Identify who owns the waterproofing, structure and equipment, who maintains each part and who can approve alterations. Have local counsel resolve conflicting provisions before the design depends on a disputed boundary.

California illustrates why these details matter. The Department of Real Estate’s 2026 statutory excerpts, including Civil Code sections 714.1 and 4746, distinguish protected rooftop solar uses from permitted association requirements. Section 4746 addresses shared multifamily roofs and allows a solar site survey with equitable allocation of usable roof area. It does not prescribe equal annual kWh for every owner.

Why Shared Roof Allocation Needs Engineering Input

An allocation rule becomes meaningful only when the roof can physically accommodate the proposed systems. Orientation, shading, access routes and equipment dimensions determine how much useful generation each arrangement can support.

The decision affects:

• Available DC capacity and modeled annual energy for each allocation
• Conduit, access and maintenance routes through common or private areas
• Equipment ownership and the approved interconnection arrangement
• Future installation opportunities for owners who are not participating yet
• How the costs and obligations will be explained when a unit is sold

Show the association both the proposed applicant’s layout and the space reserved for other owners. A nominal reservation can be unusable if it is fragmented, shaded or inaccessible. Check whether the reserved zone can accommodate actual module rectangles, access and a viable electrical route.

Use roof and array modeling to document the geometry and a consistent yield method to compare options. SurgePV supports roof modeling, layout and shading analysis; a designer must still prepare the allocation schedule and obtain the appropriate approval. Software output does not determine property rights or the legally required meaning of fairness.

The association should agree on the objective before reviewing a preferred layout. Equal usable area, similar generation, proportional entitlement and a shared system can lead to different outcomes. Make those differences visible rather than presenting a single engineering metric as the only lawful choice.

The Four Allocation Methods

The following methods are design options to compare with the governing documents and local law. None is universally required or guaranteed to survive a legal challenge.

Method 1: Equal Area Allocation

Divide the agreed usable area equally. For an illustrative four-unit building with 1,600 square feet of usable roof, each share is 400 square feet. Use area after exclusions, not the gross roof footprint.

When it can work: Similar orientation, shading, access and module fit across the assigned zones.

Limitation: Equal area can produce unequal energy. The magnitude depends on the site; a north-facing section does not universally produce half as much as a south-facing section.

Record needed: A plan showing each usable zone and a production comparison that explains any differences. Owners should understand what equal area does and does not equalize.

Method 2: Energy-Based Allocation

Allocate different amounts of usable area to target similar modeled annual generation. A more shaded zone may need more modules to approach the output of a better-exposed zone.

When it can work: Sufficient space and an approved arrangement allowing allocations to differ from the roof directly above each unit.

Limitation: Module counts are discrete, electrical constraints can differ and perfectly equal generation may be impossible. More modules can also mean higher cost, so equal energy does not imply equal financial benefit.

Record needed: The yield assumptions, allocation calculation and actual buildable layout. Distinguish this design option from a statutory requirement for equitable roof-area allocation; they are not automatically the same test.

Method 3: Pro-Rata Roof Frontage or Entitlement

Assign areas according to a documented frontage, ownership share or other agreed entitlement. For a simple row, the starting zone might be the roof directly above each unit.

When it can work: Clear boundaries and repeating geometry, with an agreement that accepts differences in solar potential.

Limitation: Hips, valleys, shared dormers and obstructions can make proportional strips unequal in usable area or generation. Check access and module fit within each strip.

Record needed: The basis for the proportions and any adjustments. A convenient drawing line is not evidence of a legal boundary.

Method 4: Phased Installation with Reserved Shares

Allow owners to install at different times while protecting the agreed opportunity for later applicants. The first applicant’s layout must leave meaningful capacity, access and cable routes for the others.

When it can work: The association adopts a complete roof plan before approving the first installation.

Limitation: Reserving only an abstract area can leave later owners with impractical fragments or an exhausted electrical route. Future changes to module dimensions and building equipment may also need a review process.

Record needed: A reservation map and rules for later changes. Do not assume priority in time gives the first owner unrestricted use of the best roof.

This is a design comparison, not a ranking of legal defensibility. California’s shared-roof provisions cited above concern equitable usable-area allocation; the local approval documents determine how a proposed method is applied.

Roof Geometry Constraints Specific to Townhouses

Measure the roof as a set of buildable zones rather than converting gross area directly into panel count. Narrow sections and shared obstructions can make module fit more restrictive than the total area suggests.

Narrow Roof Sections

Use the exact module dimensions, clamp zones and mounting instructions. For illustration, if an approved layout leaves 10 feet of clear width and each module is 3.5 feet wide, two portrait columns fit before allowing for gaps. Three do not. Rotating modules may change the count but also changes rail and attachment requirements.

Do not infer a modern module’s dimensions from an old cell-count label. Place actual rectangles in the drawing and include tolerances for the survey, installation gaps and roof irregularities. Confirm the space needed for installation and later maintenance.

Shared Valleys and Hips

A hip or valley changes the available polygon and can coincide with a property boundary or drainage path. Check the mounting manufacturer’s instructions and the approved roof layout. There is no universal clearance that can be applied to every racking system and roof type.

Avoid locating equipment where roof-water management or access would be compromised. The roofer and structural designer should review attachment locations near transitions, especially where the waterproofing responsibility belongs to the association.

Penetrations That Cross Unit Boundaries

Survey vents, flues, exhaust outlets and service equipment accurately. Required clearances depend on their function, manufacturer instructions and applicable rules. Do not use one generic clearance around every penetration.

Show service access as well as the object footprint. A vent that fits between modules may still need access for replacement. Where an obstruction serves more than one unit, identify who can authorize moving it and who pays.

Dormers and Skylights

Dormers and adjacent buildings create changing shadows. Include neighboring roof features in the shading model, not only objects inside the applicant’s proposed allocation. Verify uncertain heights on site and identify any tree-management assumption separately.

Structural Load and Roof Condition

Have the responsible professional review the actual framing, condition, attachment design and applicable loads. Building age alone cannot determine roof capacity or whether a structural letter is required. Use the selected equipment’s weight rather than a generic pounds-per-square-foot figure.

Coordinate with the roof-maintenance plan. An array installed shortly before reroofing can create avoidable removal work. Document the roof condition, warranty interfaces and intended sequence before committing to the installation date.

Electrical Architecture for Shared-Roof Townhouse Arrays

The electrical arrangement must match ownership, metering and the utility’s approved connection. Separate per-unit systems are one option; a shared system with an eligible allocation tariff can also be possible.

The CPUC’s virtual net metering and billing guidance describes allocation of generation benefits across eligible multi-tenant accounts. It states that new interested applicants generally moved to the Virtual Net Billing Tariff from February 15, 2024, with specified affordable-housing exceptions. Eligibility and the utility tariff must be checked for the property.

Microinverters with Per-Unit Circuits

A per-unit microinverter system can connect that unit’s assigned modules to its own approved interconnection point. Identify each circuit, isolator, monitoring account and equipment owner clearly.

Advantages to assess: Module-level conversion and a layout that can accommodate small or differently oriented groups, subject to product compatibility.

Limitations to assess: Roof access for equipment replacement, circuit limits, communications and the installation quote. Do not assume a universal cost premium or effortless future expansion.

String Inverters per Unit

A per-unit string inverter can provide a separate system when its voltage and current requirements suit the available modules. Keep the DC circuit and interconnection documents traceable to the appropriate owner and meter.

Advantages to assess: Inverter service location, equipment count and the actual installed cost.

Limitations to assess: Minimum and maximum string conditions, shading, mixed orientations and protection requirements. Small array size alone is not proof that a string inverter is unsuitable; check the proposed model.

A cable crossing a legal boundary requires a properly authorized route and compliant installation. Crossing the line is not automatically prohibited, but the route must be documented rather than assumed.

DC Optimizers and Shared-System Options

Optimizers can form part of a per-unit system when used with compatible inverters. Separate MPPT inputs on one inverter do not create separate utility-meter ownership or billing channels. Do not connect independent customer services to a shared inverter on that assumption.

A genuinely shared system needs a designed interconnection, an eligible billing arrangement and an agreement covering ownership and maintenance. It may serve common loads or allocate financial benefits under a utility-approved program. The legal and tariff design should precede equipment selection.

This comparison follows the distinction between physical interconnection and benefit allocation in the CPUC guidance. It is not a promise that every utility offers each option.

Fire Code Setbacks That Reduce Usable Townhouse Roof

Use the adopted local rules and the authority having jurisdiction’s approved access arrangement. Do not transfer ridge, eave, hip or penetration dimensions from a generic diagram to every townhouse.

Ask the designer to identify the building classification, applicable code edition, fire-access requirements and any accepted alternative arrangement. Check the standard for the required dimensions. Structural and waterproofing clearances are separate from firefighter-access provisions, even when they overlap on the drawing.

Build a roof-exclusion plan before allocating capacity:

• Mark the measured gross roof planes and legal-use boundaries.
• Add required access and setback polygons from the approved design basis.
• Add equipment, vents, drainage and maintenance access.
• Measure the union of excluded areas so overlaps are counted once.
• Place the actual modules, gaps and mounting system in the remaining polygons.

For illustration, a 320-square-foot section with 120 square feet of combined exclusions leaves 200 square feet. That arithmetic does not prove a particular panel count: a narrow or fragmented polygon may fit fewer modules than its area suggests. Retain the layout drawing alongside the area schedule.

Keep unresolved requirements visible. A provisional layout can support an early discussion, but it should not be labeled permit-ready while access or structural decisions remain open. If an alternative pathway is proposed, obtain the relevant acceptance before assigning the recovered area to an owner.

The Shade Study Behind a Roof Allocation

A consistent shading and yield study helps owners compare allocations. It should be dated, reproducible and explicit about uncertain inputs; it does not determine the legal allocation on its own.

Site model inputs:

• Building geometry with ownership and use boundaries identified
• Roof pitch, azimuth and the proposed array orientation
• Nearby trees, buildings, dormers, chimneys and parapets
• Penetration locations, dimensions and service-access needs
• Survey source, measurement date and unresolved height assumptions

Weather and simulation inputs:

• Site coordinates and the documented weather dataset
• The simulation time basis and horizon treatment
• Module and inverter definitions
• Temperature, soiling and other loss assumptions
• The treatment of near shading and electrical mismatch

Outputs for each candidate zone:

• Modeled irradiation on the array plane, with units
• A clearly defined shading or solar-access metric
• Specific yield in kWh per installed kW per year
• Module count, DC capacity and modeled annual AC energy
• Any route, equipment or access limitation affecting the allocation

Do not label total solar resource fraction and solar access as interchangeable metrics. Define the metric produced by the selected method and use it consistently across zones. Distinguish irradiance or irradiation from electrical energy: kWh/m² cannot be copied directly into a household’s generation forecast.

As an illustrative proportional calculation, if one equal-capacity layout produces 1,650 kWh per kW-year and another produces 1,100, the second needs 1.5 times the capacity to target the same annual energy. That assumes the specific yields remain valid as the layout expands. Re-simulate the actual placement rather than extending a shaded-zone average indefinitely.

Use shading analysis to support the comparison, with site verification where geometry is uncertain. Record which tree or obstruction changes are assumed and whether the owner has authority to make them. A modeled benefit from removing a neighbor’s tree is not an available design option without the necessary agreement.

HOA Approval Workflow

Establish the application and decision process from the governing documents and applicable law. The following sequence is a coordination checklist, not a universal timetable or requirement for a membership vote.

Step 1: Establish the Application Requirements

Ask the association or managing agent for its solar procedure, required information and decision route. Identify the property rights involved and any notices required for other owners. Keep a dated record of submissions and requests for additional information.

Step 2: Complete the Roof and Solar Survey

Survey enough of the shared roof to assess the applicant’s proposal and other owners’ opportunities. Include geometry, obstructions, usable zones, proposed equipment and future reservations. Explain the allocation method and any assumptions that still need engineering or legal review.

Step 3: Assemble the Application Package

Depending on the project requirements, the package may include:

• Roof-use plan and proposed module layout
• Production comparison and allocation schedule
• Electrical single-line and interconnection information
• Attachment details and structural review
• Equipment datasheets and installer qualifications
• Insurance information requested under the applicable rules
• Access, maintenance, removal and successor-responsibility provisions

Distinguish mandatory requirements from requested supporting information. Do not assume every association can impose the same insurance endorsement, indemnity or voting condition.

Step 4: Obtain the Required Decision

Follow the decision process permitted by the local law and governing documents. Architectural review, board action and membership voting are different mechanisms. Ask counsel to resolve any conflict rather than adding an unsupported approval step.

Step 5: Document Roof Rights and Responsibilities

Use the legal instrument appropriate to the property and jurisdiction. The agreement should identify the approved plan and explain responsibility when ownership changes. Recordation may be appropriate, but a recorded easement is not the only possible way to create enforceable obligations.

Step 6: Install, Inspect and Retain the Record

Complete the installation under the accepted association, permit and utility arrangements. Save the approved drawings, as-built changes, commissioning record and warranty information. Give the association the access and emergency information it needs to manage the common roof.

Build the project schedule from the actual review process. Avoid promising a fixed approval duration across jurisdictions. Keep the design, association review and utility application moving from the same revision so a later change does not invalidate an earlier acceptance.

Legal Agreements for Roof Use and Maintenance

The project needs a clear allocation of rights and responsibilities, but the document form depends on the jurisdiction and governing documents. Have local counsel prepare or review the arrangement.

Roof-Use, License or Easement Terms

Identify the permitted roof zone, equipment and access route. Address maintenance access, future building work, any expansion process and what happens at termination. A plan reference is more useful than a vague description such as “the roof above the unit.”

Specify how the rights and obligations pass to a buyer or successor owner. If registration or recordation is required or advisable, complete it through the appropriate legal process. Do not assume a perpetual right merely because a PV system has a long expected service life.

Damage, Indemnity and Insurance Terms

Allocate responsibility for installation damage, leaks, maintenance activity and removal. Coordinate the agreement with the actual insurance policies and local law. An indemnity clause and insurance coverage are different protections; one does not automatically provide the other.

Define how a suspected leak or fault is investigated and who can authorize urgent action. Preserve evidence and notification requirements so an emergency repair does not become an unresolved dispute over responsibility.

Removal and Reinstallation Terms

Agree on notice, contractor access, temporary storage, cost responsibility and the conditions for reinstalling the array after roof work. Include an emergency procedure where the normal notice period is impractical.

Do not assume the individual owner always bears every cost. The allocation depends on the agreement, applicable law and the reason for the work. Obtain a project-specific estimate rather than inserting a universal removal price. Address equipment that cannot be reused and changes required by the new roof or later installation rules.

Keep these obligations with the property and system handover records. A future buyer, managing agent or maintenance contractor should be able to identify the responsible party without reconstructing the original sales conversation.

Production and ROI Modeling for Townhouse Arrays

Model the actual layout, equipment and shading. There is no justified universal production penalty simply because a building is a townhouse.

A narrow roof may limit module count, and adjacent structures may affect yield. Those effects belong in the geometry and loss calculations. Applying an additional generic townhouse penalty after modeling them can count the same loss twice. A well-exposed townhouse array may also perform differently from a shaded detached-home array in the same region.

Separate annual generation from annual bill savings. Savings depend on the receiving account, consumption timing, import and export prices, allocation tariff and fixed charges. Two owners receiving equal kWh can obtain different financial benefits.

For each option, show installed capacity, modeled energy, installed cost, operating obligations and the tariff basis. Where costs are shared, explain the allocation method. Where one owner needs more equipment to achieve similar energy, show that difference rather than implying equal production creates equal payback.

Use a documented financial model with project-specific inputs. SurgePV supports energy yield and financial modeling, while shared-meter allocation and legal entitlement need the appropriate specialist review. For the broader residential workflow, see the residential design guide.

Worked Example: 4-Unit Townhouse Block

This is an illustrative design example, not a documented project or a legal allocation recommendation. All geometry, yields, prices and module dimensions below are assumed to demonstrate the calculation.

Assume four units share a roof with a 720-square-foot candidate plane facing 165 degrees. A separate rear plane is outside this example’s agreed scope, rather than automatically unsuitable because it faces north. Trees and roof obstructions cause different modeled specific yields across the four candidate zones.

Step 1: Roof Inventory

The designer would evaluate both planes in a real options study. Here the front plane alone is used so the effect of allocation can be followed without changing the roof basis between calculations.

Step 2: Apply the Assumed Exclusion Plan

The following areas are hypothetical non-overlapping exclusions. They are not code-prescribed dimensions or setback rules.

Subtract the union of exclusions, not overlapping rectangles added repeatedly. The remaining area must still pass an actual module-fit check. Neither the total nor the allocation arithmetic establishes that a buildable layout exists.

Step 3: Model the Candidate Zones

Assume 400 W modules occupying 21 square feet each. For this simplified proportional study, the modeled yields are:

The last column equals specific yield × 0.4 kW / 21 sq ft. These are assumed simulation outputs, not measured irradiation. A real study would rerun the model after moving or adding modules.

Step 4: Compare Equal Area with Equal Energy

An equal split of 300 square feet gives 75 square feet per unit. Before discrete module fitting, proportional energy would be 1,500, 1,800, 2,250 and 2,250 kWh respectively.

To target equal energy without exceeding the roof, let E be each unit’s annual energy. Required areas are E/20, E/24, E/30 and E/30. Their sum must equal 300:

E = 300 / (1/20 + 1/24 + 1/30 + 1/30) = 1,894.7 kWh per unit.

The unrounded calculation respects the area limit. Equalizing to the average energy of the equal-area case would require more area than is available. The energy target must be solved subject to the roof constraint, not chosen first and fitted afterward.

Step 5: Fit Whole Modules and Recheck the Result

Suppose an actual layout can fit a candidate allocation of four, four, three and three modules. That uses 294 square feet of module footprint, leaving six square feet of aggregate area. Gaps, shape and access still require drawing verification; spare aggregate area alone is not clearance.

This discrete candidate does not provide equal energy. Unit 2 also uses more area than its continuous target. The association must review that tradeoff or compare another placement; rounding does not silently amend the agreed rights. A shared-system alternative might allocate benefits differently if legally and commercially available.

Step 6: Compare Cost and Simple Payback

Assume installed cost of $3.10/W, no incentive and a uniform realized energy value of $0.16/kWh. These are illustrative inputs, not market quotations. Simple payback excludes financing, maintenance, degradation and future equipment costs.

The IRS residential clean energy credit page states that the credit is unavailable for property placed in service after December 31, 2025. That is why a new 2026 owner-occupied example must not assume the former federal residential credit. Other ownership structures and programs require their own eligibility review.

The practical result is that area, energy and financial return remain different objectives. Ask owners to choose an acceptable allocation using the actual module layout and tariff assumptions, rather than promising equality that the final design does not deliver.

Battery Storage in Shared-Roof Townhouse Designs

Storage must fit the approved electrical and ownership arrangement. A per-unit battery can serve designated unit loads, while a shared system needs a designed connection, allocation method and operating agreement.

Evaluate candidate locations with the equipment instructions and applicable fire, building and electrical requirements. Garages, utility spaces and outdoor enclosures have different constraints. Do not assume a party wall can be used for mounting without structural and ownership approval.

For each option, define the loads backed up, inverter power, usable energy, reserve setting and behavior during an outage. A battery sized from annual solar generation alone may not meet the required backup duration or starting loads. Keep common-area services and private loads clearly identified.

Shared storage can create additional administration, but it is not inherently impossible. The utility tariff, metering, ownership and control design determine feasibility. Address maintenance, replacement, changes in participating owners and what happens when one unit’s requested service conflicts with another’s.

Common Failure Modes

The following are design-review scenarios, not a claimed dataset of installer post-mortems. Each identifies a question that should be resolved before installation.

Allocation without a production comparison. Equal roof areas are assigned despite different shading. Prepare a consistent yield comparison and explain what the adopted allocation method equalizes.

Cable routes without authority. The shortest route crosses a private or common area without documented permission. Show the full route, fire-stopping and access requirements, then obtain the necessary rights and approvals.

Unclear roof-work obligations. The building needs reroofing after a unit has changed hands, but the new owner cannot identify the removal agreement. Keep successor obligations and system records in the appropriate property documentation and disclosure process.

Future demand confused with inverter capacity. A later owner adds an EV or heating load. A grid-connected home can still import power; increasing consumption does not by itself require a larger PV inverter. Reassess the service, circuits, tariff and any backup requirement separately from available roof capacity.

Association or permit conditions omitted. The installed finish, route or attachment differs from the accepted package. Track approved revisions and resolve changes before installation rather than treating a general solar-access right as permission for any design.

A reservation that cannot be built. An early installation leaves enough nominal square footage but blocks access or fragments the remaining roof. Demonstrate a plausible future layout and cable route when reserving other owners’ shares.

Country and State Variations

Shared-roof rights and approval procedures vary by jurisdiction and property type. These source notes identify issues to check; they are not a substitute for reviewing the building’s documents.

California. The 2026 DRE statutory excerpts cited above include shared-roof notice, insurance and survey provisions in Civil Code section 4746. Its equitable usable-area language should not be rewritten as a universal equal-kWh requirement. Review sections 714 and 714.1 alongside it when assessing association conditions.

Florida. Florida Statutes section 163.04 addresses restrictions on renewable-energy devices and refers to residential dwellings and condominium-unit boundaries. Do not infer an unrestricted individual right to occupy a common condominium roof. Determine the roof’s ownership and approval route with local counsel.

New York. Check the municipality, building scope and condominium documents separately. A rooftop requirement for a building project would not by itself allocate a private owner’s rights to shared roof space. Obtain the applicable building-department guidance for the actual work rather than assuming every retrofit follows one citywide rule.

United Kingdom. Planning and ownership consent are separate questions, and planning rules differ across the UK. Hart District Council’s residential solar guidance illustrates that conservation-area treatment depends on the installation details; it is not a blanket exclusion from permitted development. Check the local planning authority, lease and building-control requirements for the specific property.

Australia. Apply the relevant state or territory rules and the scheme’s documents. The NSW government’s sustainability guidance describes a proposal and resolution process for strata infrastructure. Its procedure should not be assumed to apply unchanged in Victoria, Queensland or another jurisdiction.

Germany. WEG section 20 addresses structural alterations and specifically includes plug-in solar devices among listed measures. Do not extend that specific treatment automatically to an individual’s full common-roof PV array. Review the proposed system, association resolution and cost allocation together.

The designer should retain the legal and approval assumptions with the layout. If an ownership or voting issue changes, revisit the allocation and equipment arrangement before issuing the final proposal.

Insurance Implications

Ask the owner, association and installer to review the proposed arrangement with their insurers. Coverage and responsibility depend on the policies, contracts and local law; there is no supported universal premium increase.

For the unit owner, establish how the array is covered, what liability applies and whether removal or reinstatement is insured. For the association, check the effect on the common roof and master policy. For the installer, verify the required contractor coverage and evidence before work begins.

An additional-insured endorsement may be relevant, but do not assume it is mandatory or available under every homeowner policy. Have the broker explain any exclusions and coordinate the wording with counsel. Avoid promising that another unit’s coverage is unaffected without insurer confirmation.

Record who reports a loss, who arranges emergency work and how costs are handled while responsibility is investigated. Retain required certificates and renewal records. An insurance plan is most useful when the managing agent can act on it during a leak or equipment incident, not only when the installation is first approved.

Three Action Items for Townhouse Solar Design

A shared-roof project needs a buildable layout, an approved electrical arrangement and documented roof rights. Resolve those together before promising a system size or savings figure.

• Compare allocation options using the same model. Show usable area, whole-module fit, annual energy and cost for each unit, including non-participating owners’ reserved opportunities.
• Match metering to ownership. Compare separate systems, common-load service and eligible shared-benefit arrangements with the utility and project advisors.
• Document maintenance and changes of ownership. Use the appropriate legal records for access, damage, roof work and successor responsibilities, and retain the approved design revision.

To review the supported modeling steps, book a SurgePV demo with your roof plan and proposed allocation options. Keep the legal allocation and utility approval decisions with the professionals responsible for those parts of the project.

Frequently Asked Questions

How is shared roof space divided for townhouse solar?

Shared roof space is divided according to the governing documents, applicable law and approved allocation method. Compare usable area, shading, module fit and future owners’ opportunities. Equal area and equal annual energy are different objectives.

Can a townhouse owner install solar without association approval?

The required approval depends on roof ownership, governing documents and local solar-access law. A protected right to install solar does not automatically remove all reasonable application requirements. Resolve the applicable process before work begins.

Does every townhouse need a separate solar inverter?

Separate per-unit systems are one option, but eligible shared systems and benefit-allocation tariffs may also be available. The approved interconnection and billing arrangement determine the architecture. Separate inputs on one inverter do not create independent utility-meter connections.

How much roof area does a 5 kW townhouse system need?

The required area depends on module dimensions, whole-module count and the approved layout. Thirteen 400 W modules provide 5.2 kW, before considering whether they fit. Add the project-specific access, mounting and service requirements rather than using a universal gross-area allowance.

Who pays for removing panels when a shared roof is repaired?

The cost responsibility comes from the applicable law and the project’s agreements. Specify notice, access, storage, removal and reinstallation obligations before installation. Address successor owners and emergency roof work explicitly.

Can equal-energy allocation give every owner equal payback?

Equal modeled energy does not guarantee equal payback. Owners may need different equipment quantities and face different consumption patterns, tariffs and allocated costs. Compare financial outcomes separately from the roof or energy allocation.