When comparing solar panel companies, start with the system each one proposes, not the headline price. A useful quote should show how the design suits your roof, electricity use and plans for battery storage, then spell out the equipment, installation work, exclusions and after-sales support. Two proposals that appear similar can deliver different results if one assumes a smaller system, omits electrical upgrades or uses more optimistic savings estimates. Ask each company to explain its assumptions in writing. That gives you a fairer basis for comparing costs and helps you judge whether a lower quote is genuinely better value.
Before you assess which company offers the best deal, check that the proposals cover comparable systems and work. If one quote includes a battery and another does not, or the panel capacity differs, the totals do not tell you much by themselves. Ask each provider to identify the proposed system capacity, key equipment models, expected generation and every part of the installation included in the quoted price.
| What to compare | Ask the company | A clear proposal should show | Look closer if |
|---|---|---|---|
| System design | How does the layout fit my roof and electricity use? | Panel layout, system capacity, shading assumptions and generation estimate | The design is generic or the estimate has no stated assumptions |
| Equipment | Which panel, inverter and battery models are included? | Manufacturer and model details, with relevant warranty terms | The quote names only a brand or says equipment may be substituted |
| Installation scope | What work is included, and what could cost extra? | Mounting, wiring, connection work, monitoring setup and stated exclusions | Important work is described as “standard” without explanation |
| Financial estimate | How were the savings and payback estimate calculated? | Generation, self-use, exported electricity and tariff assumptions | Savings are presented as guaranteed or without a clear calculation |
| Support | Who handles faults, warranty claims and system monitoring? | A named point of contact and a clear process for service requests | The installer and equipment supplier appear to pass responsibility between them |
Use the table as a prompt for questions, not as a scoring system. A company may have a sound reason for proposing a different layout or product; what matters is whether it explains the choice and makes the trade-offs understandable.
A good solar design begins with your property and usage, rather than a standard package. The installer should ask for information about your electricity consumption and, where available, when you use power. A household that uses more electricity during daylight may be able to use a larger share of its solar generation directly. If much of your consumption happens in the evening, ask how that affects the proposed system and whether a battery is being considered for a specific reason.
Review the roof plan as well as the headline system size. Ask which roof sections will carry panels, whether shading or obstructions affect the layout, and whether the company has allowed for the roof’s condition. If the proposal depends on assumptions about shading, orientation or future electricity use, request those assumptions in writing. A site assessment should give you a chance to correct information that could change the design.
Look at the generation estimate with care. Ask what period it covers, what site details were used and whether it represents estimated production rather than a promise. The estimate should be connected to your expected use and electricity plan. In New Zealand, the value of electricity you export depends on the arrangement available through your retailer, so confirm which export rate or plan assumption the company has used and whether you would need to change plans.
A battery can store some solar electricity for use later, but it adds equipment and cost. Ask the company to compare the proposal with and without storage, using the same assumptions about your household’s use and electricity rates. The comparison should explain what changes in the expected amount of electricity used at home, what is exported and how the battery’s capacity and operation affect the result.
Be cautious if a battery is presented as essential without a clear explanation of your consumption pattern or priorities. It may suit a household seeking more control over when it uses solar electricity, but it should be assessed as a separate decision rather than accepted as an automatic part of every system.
Ask for the exact model of each major component: panels, inverter and, if included, battery. A brand name alone is not enough to identify what you are buying. Models within a product range can differ, and an installer should be able to explain why the selected equipment fits the system design.
Read warranty information as separate pieces. Panel product and performance warranties, inverter or battery warranties, and the installer’s workmanship coverage may have different terms and claim processes. Ask who you contact if a component fails, who arranges an inspection and whether the installer will help coordinate a claim with the manufacturer. A long warranty has limited practical value if you cannot establish who is responsible for handling it.
Also ask whether the proposed inverter supports the system layout and any battery plans you are considering. If you may want storage later, find out what additional equipment or work could be needed. “Battery-ready” can mean different things in different proposals, so ask the installer to describe what the phrase means for the particular model and system.
The equipment list does not tell you everything about the finished project. Compare the work each company has allowed for, including panel mounting, wiring, inverter placement, system monitoring setup and the connection arrangements needed for your property. Ask who will deal with any approvals or applications that apply to the installation, and what documents you will receive when the work is complete. Requirements can depend on the property, system and local network, so have the company identify the relevant steps for your project.
Pay particular attention to work that might sit outside the quoted scope. Examples to clarify include repairs to a roof, changes to a switchboard, extra cabling, access equipment and any work needed to resolve an issue discovered during installation. These items may not apply to your home, but the proposal should say how the company will handle them if they do. Ask whether extra work requires your approval before it is carried out and how any additional cost will be explained.
Find out who will perform the work. Some solar panel companies manage the whole project, while others use subcontractors or coordinate work with separate suppliers. That arrangement is not automatically a problem, but you should know which business is responsible for scheduling, installation quality and follow-up. For electrical work in New Zealand, ask who will carry it out and check that the relevant workers have the required registration through the Electrical Workers Registration Board (EWRB).
Once the designs and scopes are comparable, review the total price and the assumptions behind the financial forecast. A lower quote may represent good value if it provides a suitable design and clearly includes the necessary work. It may also be lower because it covers fewer panels, different equipment, fewer installation tasks or less support. Find the difference before deciding.
Ask each company to show how it estimated savings. The calculation should distinguish between electricity you expect to use directly and electricity exported to the grid, and state the electricity prices or export rates used. It should also make clear whether the estimate assumes that your usage, tariffs or system performance will stay constant. Actual results can differ as household consumption and electricity arrangements change.
Do not compare projected payback periods unless the underlying assumptions match. A longer forecast may result from a more cautious estimate; a shorter one may rely on a higher export rate, greater self-consumption or other assumptions. Ask the provider to explain which factors have the most influence. If you are considering finance, compare the total amount payable and the repayment terms with the system’s estimated financial benefit. Keep financing costs distinct from the solar system’s projected savings.
Ask how any incentives or support have been treated in the quote. Availability and eligibility can change, so confirm current details for your location and circumstances rather than relying on an assumed discount. A proposal should make it possible to see the system cost without an incentive as well as any amount that depends on one.
Check which legal entity will sign your contract and take responsibility for the work. If a sales company, installer and equipment supplier are different businesses, ask how their roles fit together. Get the answer in writing, especially for faults that could involve both installation and equipment warranties.
Ask what support looks like after commissioning. Find out how to report a fault, whether the company can access monitoring information with your consent, and what happens if the original installer is no longer available. You should also receive clear instructions for using the system and understand what monitoring alerts do—and do not—tell you. A company’s answer to these practical questions can reveal more than a broad promise of “ongoing support.”
Before signing, read the contract for the agreed equipment, scope, payment stages, estimated timing, exclusions and process for approving variations. Check that the final written proposal matches what you discussed. If a salesperson has made a claim about output, savings or future battery compatibility, ask for it to be included in the documents rather than relying on a verbal assurance.
Compare enough proposals to understand the range of system designs and installation scopes available for your home. There is no fixed number that suits every project; the useful test is whether you have enough detail to spot differences and ask informed follow-up questions.
Not automatically. A larger system may generate more electricity, but its value depends on your roof, household use, export arrangements and the system’s cost. Ask the installer to explain why the proposed capacity suits your needs and how a smaller or larger option would change the estimate.
Only after checking that the assumptions are comparable. Estimates can use different expectations for solar generation, daytime self-use, electricity rates and exported power. Ask each company to state these inputs so you can see whether a difference comes from the system design or from the calculation.
No single answer fits every household. A battery may make sense for your usage pattern or preferences, but it changes the system cost and expected use of solar electricity. Ask for a clear comparison of the proposed system with and without storage before deciding.
Ask for the promise to be clarified in writing before you sign. This applies to equipment, expected output, included work, warranty support and future battery options. If the company cannot explain how the statement fits the contract, treat it as unresolved.
The strongest choice is the solar panel company that can explain its design, scope and financial assumptions in terms you can verify—not simply the one with the smallest total. Compare equivalent proposals, settle questions about exclusions and support, then choose the system that fits your roof, electricity use and budget.
