ADU loads, tile roofs, and service capacity in Hacienda Heights 91745

ADU loads should be based on the actual permitted equipment

Estimate HVAC, hot water, cooking, refrigeration, laundry and EV charging from the ADU's approved design where possible.

Ask whether the ADU shares the main service and meter and how the load affects the electrical calculation.

Compare current-household and post-ADU solar sizing scenarios.

Tile-roof condition should be checked before both projects are locked

Ask how solar attachments will be made, how flashing will be handled and how broken tiles will be replaced.

If the roof is older, inspect underlayment and waterproofing before solar is installed. ADU construction can be a useful time to coordinate roofing work if needed.

Keep roofing and solar warranties separate.

Service capacity should include the ADU and future electrification

An ADU can add substantial electrical load. Add EV chargers, batteries or heat pumps and the main service may become the limiting factor.

If an upgrade is recommended, request the calculation and ask whether load management could reduce the scope.

If SCE-side work is required, include utility scheduling in the project timeline.

County permitting should coordinate solar and ADU work

Hacienda Heights uses the County permit process. Ask whether the ADU and solar projects are being reviewed as coordinated scopes or separate permits.

If solar is going on the ADU roof, verify that the structure is permitted and structurally suitable before finalizing the layout.

Ask who handles EPIC-LA submissions, corrections and inspections.

Battery backup should reflect both living spaces

If the main house and ADU share service, identify critical circuits in both spaces. The load plan should reflect who actually depends on backup power.

Ask for continuous and surge power, usable energy and runtime under the selected loads.

If storage is being sold for savings, compare the same array without the battery.

SCE modeling should use post-ADU load when appropriate

A future ADU can increase daytime and evening load. Ask how that changes self-consumption, exports and system size.

Do not let the model assume full ADU occupancy years before it is likely without showing a current-load scenario too.

Use conservative rate assumptions and keep all future-load estimates visible.

Coordinate the ADU roof, tile roof, and service plan before either structure is treated separately

If solar may use roof area on both the main house and ADU, ask the designer to compare roof orientation, shade, tile condition and conduit distance across both structures. The closest roof is not always the best solar surface, and the best solar surface is not always the easiest place to route electrical equipment.

The ADU's final electrical design should also be incorporated into the service calculation before the array is sized. A new HVAC system, water heater, induction range or EV charger can materially change both annual usage and peak demand. Ask for the permitted equipment schedule rather than a generic ADU estimate whenever it is available.

If the main house has older tile or underlayment while the ADU roof is new, compare placing more of the array on the newer structure against the cost of longer conduit runs or more complicated interconnection. That trade-off should be explicit instead of accidental.

Finally, confirm that both structures are fully permitted and structurally eligible to support the proposed array. Solar should not be used to create a new compliance problem on top of an unresolved building issue.

Decide whether the ADU should influence array size now or later

If the ADU is approved but not yet built or occupied, ask the installer to show two system sizes: one based on current household use and one based on the expected post-ADU load. The difference reveals how much of the proposed array is being purchased for future demand.

Then consider timing. If the ADU is likely to be occupied within a year, including the future load now may be practical. If construction is uncertain or several years away, preserving a clean expansion path may be more rational than exporting excess energy in the meantime.

Ask how expansion would work technically. Roof space, inverter capacity, equipment compatibility and utility rules can affect whether later additions are simple or complicated.

The homeowner should choose the timing deliberately rather than allowing the ADU to become a vague justification for the largest possible array.

Hacienda Heights 91745 homeowner checklist

Gather SCE bills, ADU plans, tile-roof condition, service-panel information, EV plans and battery priorities.

Compare system size, production, service upgrades, roof work, storage, County permit scope and total project price.

Ask who handles inspections, interconnection, monitoring and service after installation.

How Home Solar Simplified reviews a solar proposal

Every local guide uses the same homeowner-first review standard so a proposal can be evaluated without relying on a sales presentation. Start with the home's actual electric bills and identify which future loads are genuinely likely: electric vehicles, heat pumps, electric water heating, pool equipment, an accessory dwelling unit, or battery storage. Ask the installer to separate today's usage from future assumptions instead of blending them into one unexplained annual number.

Next, compare the physical system. Write down the proposed DC system size, first-year production estimate, degradation assumption, module and inverter models, battery usable capacity and power rating if storage is included, roof planes used, shade assumptions, attachment method, equipment locations, and any service-panel or roofing work. The production model should match the final permitted layout. If panels move during engineering, HOA review, planning review, or permit corrections, request an updated production estimate before installation.

Then compare money on a cash-price basis before looking at monthly payments. Ask for the cash price of the solar array, battery, roof work, service upgrade, EV charger, trenching, permits, and other add-ons as separate line items. If financing is used, compare the financed amount, interest rate, term, dealer fees or prepaid finance charges, total scheduled payments, and prepayment rules. Tax-credit assumptions should be treated as estimates for discussion with a qualified tax professional, not as guaranteed discounts from the contractor.

Review the utility assumptions separately. The proposal should identify the actual electric utility, current rate structure, estimated self-consumption, exports, remaining grid purchases, and any battery dispatch strategy. A city, ZIP code, or neighboring home does not prove the exact service arrangement at a property. Utility rules, rates, interconnection requirements, and equipment eligibility can change, so the installer should confirm the current rules for the specific account before the homeowner relies on projected savings.

Finally, review responsibility after the sale. Ask who handles permit corrections, utility interconnection, inspection failures, monitoring problems, inverter or battery warranty claims, roof leaks near attachments, and future array removal for roof work. Keep the signed contract, approved plans, equipment cut sheets, inspection record, permission-to-operate documentation, warranties, and final one-line electrical diagram together. A solar project should remain understandable years after the original salesperson is gone.

When comparing two or three proposals, normalize them before deciding. Put the same fields into one worksheet: cash price, financed price, system size, first-year production, estimated annual consumption, future-load assumptions, battery capacity and power, roof work, service upgrades, permit responsibility, workmanship warranty, equipment warranties, monitoring support, and the estimated utility bill that remains. If one proposal uses a different roof layout, rate assumption, financing term, utility escalation rate, or battery operating strategy, mark that difference instead of treating the monthly payments as directly comparable. Ask each contractor to correct obvious assumption mismatches so the homeowner is comparing systems on equal footing. The lowest payment is not necessarily the lowest project cost, the largest array is not necessarily the best value, and the highest production estimate is not necessarily the most credible. A useful comparison makes the assumptions visible enough that a homeowner can explain why one proposal is stronger without repeating a salesperson's slogan.

Related homeowner research

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