When comparing solar energy companies, ask each one to price a system designed for the same home and the same energy needs. A low total can reflect a smaller system, different equipment, excluded electrical work or limited after-sales support. Compare the proposed design, expected generation, installation scope, warranties and final payable cost before weighing the quotes. In New Zealand, also clarify who will manage the connection process with your local lines company and what happens if you later need repairs. A like-for-like comparison makes it easier to see whether a quote offers genuine value or simply leaves important costs and responsibilities unclear.
A suitable solar system depends on how much electricity your household uses and when it uses it, as well as the usable roof area. A company should ask about your electricity bills or usage data, the roof’s condition and layout, nearby shading, and any plans that could change demand, such as adding an electric vehicle or replacing a heating system.
Ask each company to explain why it recommends a particular system size. A larger array may generate more electricity over the year, but that does not automatically mean better value if much of the output is exported when your household is not using it. A smaller system may better fit a limited roof or a household with lower demand. The design should reflect your circumstances rather than a package chosen for convenience.
Estimated annual generation is useful only when you understand how it was calculated. Ask what location, roof orientation and pitch, shading, equipment, and system losses the estimate assumes. If a company has not inspected the roof, ask which details are provisional and whether the design or price could change after a site visit.
Compare estimates on the same basis. One proposal may assume more usable roof space or less shade than another, which can make its forecast look stronger without representing a better system. Ask whether the estimate shows generation by month, and how much electricity the company expects you to use directly rather than export. Treat savings projections as estimates, not guaranteed outcomes: your future usage, electricity prices, export arrangements and system performance all affect the result.
Request written proposals that identify the system components and installation work in enough detail to compare. The table below highlights where apparently similar quotes can differ.
| What to compare | What the proposal should explain | Question to ask |
|---|---|---|
| System design | Proposed array size, roof layout, shading assumptions and estimated generation | How does this design fit my actual roof and electricity use? |
| Panels and inverter | Manufacturer and model for each main component, plus any stated warranty terms | Are these exact models included, or can they be substituted? |
| Battery, if included | Usable storage capacity, compatible inverter and intended operating purpose | Does the proposal include backup circuits, or only storage for normal use? |
| Installation scope | Mounting, wiring, switchboard work, access arrangements, testing and clean-up | Which likely extra costs are excluded from this price? |
| Approvals and connection | Who handles applications, required information and coordination with the local lines company | What do I need to do, and when can the system be switched on? |
| Support and warranties | Product, workmanship and performance terms, plus the contact for service | Who handles a fault, and what response process should I expect? |
| Price and payment | Total payable amount, inclusions, exclusions and any financing costs | Is this a cash price, and what is the total cost if financed? |
Use the table as a prompt for a consistent set of questions, not as a scoring system. A proposal that supplies more detail is easier to assess, but detail alone does not prove that the design or price is right. If an important item is missing, ask for it in writing before comparing totals.
Panels are only one part of a home solar system. Ask for the make and model of the panels, inverter and, where relevant, battery. Then compare the equipment included in each quote rather than relying on a brand name or a general description such as “premium components.” If a proposal allows substitutions, find out whether you will be told before a different product is installed.
The inverter converts the panels’ output into electricity your home can use. The right arrangement depends on the roof layout, shading, system design and whether a battery is part of the plan. Ask the company to explain why it has chosen that inverter configuration for your site, and what monitoring is included. A clear answer should connect the equipment choice to the proposed design, not just describe a product as popular or advanced.
Compare a solar-only proposal with a battery option as separate choices. A battery can store some daytime generation for later use, but whether it makes financial sense depends on household patterns, the system design, electricity plan and total installed cost. Ask the company to show the assumptions behind any savings estimate and to explain how the result changes if your usage or export arrangements differ.
Do not assume that including a battery means your home will have power during a grid outage. Backup operation may require compatible equipment, specific wiring and designated backup circuits. Ask exactly which parts of the home would be supplied, under what conditions, and whether those items are included in the quoted price. If backup power is important to you, make it a written requirement rather than relying on the word “battery.”
Two quotes can name similar components yet cover different amounts of work. Check whether the price includes mounting hardware, wiring, installation labour, system testing, monitoring setup and any switchboard changes the company has identified. Also ask how the installer will deal with access, roof penetrations, cable routes and making good any affected areas.
Roof condition matters. If repairs or reroofing may be needed, discuss the sequence before accepting an installation date. Removing and reinstalling panels later can add work, so ask whether the proposed mounting approach suits the roof and what the company recommends if its condition is uncertain. Do not assume that roof repairs, scaffolding, electrical upgrades or other additional work are included unless the quote says so.
Clarify the process for network connection. In New Zealand, requirements and responsibilities can depend on the local lines company and the proposed system. Ask which party prepares and submits the application, whether the company needs information or signatures from you, and who confirms that the system is ready to connect. Also ask whether any council or other site-specific requirements have been identified. Get the expected sequence in writing, without treating an estimated installation date as a guarantee that all approvals will be complete by then.
Find out who will carry out the electrical work and who is responsible for the overall installation. Ask for the names of the electrical workers involved and how to verify their registration with the Electrical Workers Registration Board (EWRB). If subcontractors will be used, ask which company manages the work and whom you contact if something needs attention.
Look for a written contract that identifies the equipment, price, scope, exclusions, payment schedule and process for changes. Ask how variations are approved and whether additional work requires your written agreement before it begins. A clear contract helps prevent a low initial quote from becoming difficult to compare once assumptions are replaced with extra charges.
Before signing, ask for the warranty documents and check who provides each one. Panel and inverter product warranties, battery terms, installation workmanship coverage and any performance commitment are different things. Confirm what each covers, how a claim is started, and whether any conditions apply to monitoring, maintenance or system use. Avoid treating a long warranty period as proof that service will be simple; the company’s role in handling a claim matters too.
Compare the total price for the same scope of work. Check whether the quote states the total payable amount, how tax is handled, what is excluded, and whether the price could change after inspection. Ask for separate pricing for optional batteries, switchboard work or other additions so you can see what drives the difference.
If finance is offered, compare the total amount repayable rather than just the regular payment. Ask about fees, interest, the length of the agreement, early repayment conditions and whether the finance arrangement affects equipment ownership or warranty claims. A lower upfront payment can come with a higher overall cost, so keep the cash price and financed price distinct.
Be cautious with savings or payback estimates that depend on fixed electricity prices, constant household use or a particular export rate. Ask what assumptions the company has used and whether it has accounted for the difference between electricity you use directly and electricity sent to the grid. Export rates and retail electricity arrangements can vary by provider and change over time, so confirm the terms that apply to your own plan before relying on them in a financial calculation.
If one proposal is much cheaper, ask the company to explain the difference line by line. It may reflect a smaller array, different equipment, less installation work or a more limited service arrangement. The explanation may be reasonable; the point is to find out before treating the lowest total as the best value.
The most suitable company is the one that can explain a system designed for your home, provide a clear installation scope and stand behind its work. A lower quote may be the better choice when it covers the same equipment and services without leaving important risks unaddressed. A higher quote may be justified by a more suitable design, clearer support or work that another proposal excludes, but ask the company to show exactly what accounts for the difference.
Before deciding, make sure you can answer three questions: What will be installed? What is not included? Who is responsible if the system, connection or paperwork needs attention? If the answers are specific and consistent across the documents, you can compare solar energy companies on value rather than headline price alone.
There is no fixed number that suits every project, but comparing multiple written proposals can reveal differences in design, equipment and installation scope. Give each company the same household and roof information so the proposals are easier to compare.
Location alone does not establish the quality of a proposal. Consider whether the company clearly explains who will install the system, manage connection steps and provide service after handover, and how it handles work if a subcontractor is involved.
System size is a useful starting point, not a complete comparison. Check the roof layout, expected generation, equipment models, installation inclusions and any battery or backup provisions as well.
No single answer applies to every household. Compare the added cost with your usage patterns and the proposal’s stated assumptions, and ask whether the battery is intended for energy shifting, backup, or both.
Ask for the exact make and model, along with written confirmation of whether substitutions are allowed. If the company cannot provide that information before you commit, you cannot reliably compare the equipment or its warranty terms with another proposal.
