Solar panel companies are best compared by the quality and completeness of the project they propose, not by panel price alone. A useful quote should match your roof, electricity use and plans for batteries or future changes, while clearly setting out installation work, warranties, connection steps and payment terms. For a New Zealand home, also ask how the system’s estimated generation relates to your location and how exported electricity is treated under your electricity plan. Compare proposals on the same assumptions, then check who will do the work and what support you’ll receive if something goes wrong.
Before requesting quotes, gather a few details: recent electricity bills, the roof’s age and condition, any known shading, and when your household typically uses power. You don’t need to design the system yourself. These details help companies prepare proposals based on your circumstances rather than a standard package.
Think about how long you expect to stay in the home and whether your priorities are reducing bills, adding battery storage, preparing for an electric vehicle or having some backup power during outages. These goals can point to different system designs. For example, a battery may support backup needs, but a system intended mainly to lower bills should be assessed on how much solar power your household can use as it is generated.
Tell each company about planned changes that could affect consumption, such as a heat pump, electric vehicle or major renovation. An installer can consider these in the design, but ask for the assumptions to be shown. A larger system is not automatically better if it produces more electricity than you can use or export on terms that make sense for you.
Put proposals side by side and check whether they describe the same scope. A cheaper quote may exclude work another company has included, or it may use different assumptions about system size, expected generation or battery capacity. If a quote leaves an item unclear, ask for a written answer before comparing totals.
| What to compare | What a clear proposal explains | Questions to ask | Potential warning sign |
|---|---|---|---|
| System design | Panel and inverter models, system capacity, roof layout and estimated generation | How were shade, roof direction and household use considered? | A standard package with no explanation of how it fits your roof |
| Installation | Included electrical and roof work, access arrangements, connection responsibilities and exclusions | Who handles any network application, and what could change the scope? | Unclear responsibility for approvals, extra work or final connection |
| Warranties and support | Separate product, inverter, battery and workmanship terms, plus the contact for service | Who handles a fault, and what labour or call-out costs may apply? | A general “warranty included” claim without written terms |
| Battery and backup | Whether storage is included, its usable capacity, operating limits and backup arrangements | Which circuits would operate during an outage, if backup is offered? | Backup implied in the sales pitch but not specified in the design |
| Price and finance | Total project price, included items, payment schedule, fees and financing terms | What is the total amount payable, and what happens if work is delayed? | A low headline payment with unclear fees or contract conditions |
The table is a starting point, not a scoring system. Give more weight to the items that matter to your home: a roof needing repairs, a preference for backup, or a limited budget may make one proposal more suitable even if it is not the cheapest.
Panels are visible, so quotes often emphasise their brand or rated capacity. Those details matter, but they don’t show how well the full system is designed. Ask for the proposed panel layout and the make and model of the inverter. Check that the proposal explains how the equipment works together and whether any limits affect system output.
Expected generation should be an estimate based on your roof and location, not a guaranteed bill reduction. Ask what the estimate assumes about roof direction and pitch, shading, system losses and the months when production is likely to be higher or lower. A monthly estimate can be more useful than a single annual figure because it helps you compare solar generation with seasonal household use.
Have the installer explain any difference between the system’s rated capacity and the generation forecast. If two companies give noticeably different estimates for similar equipment, ask each to show its assumptions. Differences may arise from shading estimates, roof layout or calculation methods; the important point is that you can understand and compare them.
If you may add a battery later, ask whether the inverter and system design can accommodate one, and what equipment or additional work that would require. “Battery-ready” can mean different things in sales materials, so get the proposed configuration and limitations in writing. The same applies if you expect to add another major electrical load: ask whether the current design can be expanded and what might need to change.
Ask what happens if the site inspection finds a problem the initial quote did not account for. Roof condition, access, switchboard work or shading may affect the design or installation. A reliable proposal should identify known exclusions and explain how any extra cost or change in scope will be approved.
Two solar panel companies may quote for similar equipment but different installation scopes. Check whether the price includes mounting hardware, electrical work, monitoring setup, access equipment and removal of packaging or other job waste. Confirm whether roof repairs or switchboard changes are excluded, if they could be relevant to your home, and who will arrange them.
Ask who will carry out the work and who is responsible for supervising it. The company selling the system may use its own staff, subcontractors or a combination. That arrangement is not automatically a problem, but you should know who your contract is with, who to contact during installation and which business is responsible for resolving defects.
For a grid-connected system, clarify who manages the relevant connection process with your local electricity network and what must happen before the system is switched on. Procedures can depend on the network and the system design. Ask the installer to explain what electrical compliance documents you will receive and who will provide them.
Get the expected installation sequence and payment milestones in writing. Don’t assume that a verbal promise about timing, access or included work forms part of the contract. If your roof needs attention first, settle who will do that work and when the solar installation can proceed.
A solar project can involve several warranties, and they don’t all cover the same thing. Panel product terms concern the equipment itself; performance terms concern how panel output is warranted over time. Inverter and battery warranties have their own conditions, while a workmanship warranty relates to the installation. Ask for each set of terms rather than relying on a general statement that the system is covered.
Check the duration, what is excluded, and how a claim is handled. Find out whether labour, travel or removal and reinstallation costs are included if a component needs attention. Ask whether the warranty depends on particular monitoring, maintenance or installation conditions. The answer should be available in writing before you sign.
Also consider the installer’s role after handover. If the company ceases trading, the manufacturer’s equipment warranty may still have value, but arranging diagnosis and replacement could be more difficult. Ask who provides ongoing support, how faults are reported and whether the company offers a service contact separate from the sales representative.
Ask each company to price the system with and without a battery, where both options are feasible. A battery can store some solar generation for later use, but whether it suits you depends on your consumption pattern, electricity plan, battery cost and the value you place on backup. Don’t accept “you need a battery” as a complete explanation.
Compare usable storage capacity and power output, not just the battery’s headline size. Ask whether the proposal includes backup during a grid outage. Some arrangements may supply only selected circuits, and backup capability can depend on additional equipment and system configuration. Have the company list what would and would not keep operating.
Clarify the battery’s operating limits, warranty conditions and compatibility with the inverter. Ask whether the design can be expanded later and whether doing so would require replacing existing equipment. If the battery is being financed with the panels, compare the total cost of that combined package with a panel-only option rather than focusing on the monthly payment.
Request the full project price and make sure you know what it includes, including applicable tax, installation and any stated fees. If you are considering finance, compare the total amount repayable, interest and fees, repayment period, deposit requirements and any conditions for early repayment. A lower regular payment can still mean a higher overall cost.
Ask whether the finance agreement is separate from the installation contract and when repayments begin. Confirm who owns the equipment during the agreement and what happens if you sell the property or want to pay the balance early. Read the contract rather than relying on a salesperson’s summary, and don’t sign until unclear terms are explained.
For projected savings, ask the company to show how it estimates the electricity you will use directly, the electricity you may export and the value assigned to each. Export rates and electricity plans can differ, so don’t assume exported power is worth the same as electricity you avoid buying. Ask which plan assumptions were used and whether the estimate accounts for your household’s pattern of use.
Treat payback figures as estimates, not promises. They depend on assumptions about future electricity use, prices, system performance, maintenance and any export payments. Compare the assumptions behind each forecast; a confident headline figure is less useful than a model you can understand and adjust.
When assessing a company, look for clear answers and a willingness to explain trade-offs. Ask for references or examples of comparable residential installations if you want to understand its experience, but focus on what the evidence tells you about work similar to your own. A polished presentation is less useful than a precise scope and a named point of contact for problems.
If two quotes are similar, first resolve any gaps in scope or assumptions. Ask both companies to confirm the same system configuration, generation method, battery option and installation inclusions. Then compare the differences that affect your priorities: service responsibility, warranty support, payment risk and how well the design fits your roof and usage.
The lowest quote may be a reasonable choice if it includes the work you need, uses a suitable design and provides clear support. It is less attractive if the price depends on unconfirmed work, omits likely costs or relies on savings assumptions you cannot verify. A higher quote also needs justification; ask what additional value it provides rather than assuming a premium means better quality.
Not necessarily. Panel efficiency describes how much power a panel can produce from a given area, but it does not by itself determine the best system for your roof or household. Compare the full design, expected generation, equipment terms and installed cost.
Duration is only one part of the comparison. Check what each warranty covers, its exclusions, claim process and whether labour or removal costs are included. Product and performance warranties are different, so read both sets of terms.
Not every home does. Compare a battery and panel-only proposal using your likely power use, export arrangements, total cost and any backup needs. Ask the company to explain the assumptions behind its recommendation.
Sometimes, but the answer depends on the inverter, system configuration and battery compatibility. If you may add storage later, ask the installer to specify what the current design can support and what extra equipment or work could be needed.
Ask for the calculation and the assumptions behind it, including generation, household self-consumption, export payments and electricity prices. Treat the result as a forecast rather than a guarantee, and compare it with other proposals using the same assumptions.
Choose among solar panel companies by matching the proposal to your roof, electricity use and ownership plans, then confirming the full installation, warranty and finance terms in writing. If a quote cannot explain how its design and savings estimate were reached, ask for clarification before you commit.
