The best solar companies are the ones that can explain, in writing, why their proposed system suits your home—not simply offer a low price or familiar panel brand. For New Zealand homeowners, a useful comparison starts with roof condition, household electricity use and the amount of solar power likely to be used at home. Then check the inverter and battery design, installation responsibilities, network connection process, warranties and financing terms. Ask each company to price a comparable system and show the assumptions behind its savings estimate. A well-supported proposal should make it possible to see what you’re buying, what could change the result and who will help if a problem arises.
A capable installer begins by learning how your household uses electricity and what you want the system to do. You might want to reduce purchases from the grid, prepare for an electric vehicle, add a battery later or keep selected appliances running during an outage. Those goals can lead to different system designs, so a proposal that recommends the same equipment and size for every home deserves closer scrutiny.
The company should also explain the limits of its estimate. Solar output depends on factors such as roof direction, shading, panel layout and local conditions. Savings depend on when you use electricity, your import and export rates, and the system’s installed cost. Treat projected savings as an estimate based on stated assumptions, not a guaranteed bill reduction.
Some providers manage the whole project; others sell the system and arrange installation through subcontractors. Either model can work, but you should know which business is responsible for design changes, installation quality, warranties and follow-up service. Get the main responsibilities in writing before paying a deposit.
Three quotes are useful only if they describe comparable systems. If one includes a battery, upgraded switchboard work or different installation conditions, its total cannot be compared directly with a simpler proposal. Use a table like this to identify what each price includes and what remains uncertain.
| What to compare | Ask the company | A strong proposal should explain | Look more closely if |
|---|---|---|---|
| System design | How was the system size and panel layout selected? | Roof assumptions, shading, expected output and how the design matches your use | The proposal gives a standard package without discussing your roof or electricity needs |
| Equipment | Which panels, inverter and optional battery are included? | Exact models, system compatibility and how equipment warranties are handled | Products are described only by brand, or substitutions are allowed without your approval |
| Installation | Who carries out the work and manages approvals? | Work scope, electrical sign-off, network steps and any exclusions | Responsibility is passed between a salesperson, installer and subcontractor without clear ownership |
| Costs and savings | What is included in the total, and how were savings estimated? | Itemised costs, assumptions about electricity use and export, and financing costs if applicable | The estimate relies on a large savings claim but provides no assumptions or calculation method |
| Support and warranties | Who do I contact if equipment or installation fails? | Separate coverage for products and workmanship, plus a clear service contact | Warranty terms are only verbal or depend on an unclear chain of providers |
Ask the installer to explain the recommended system size in relation to your household’s consumption. A larger array may produce more electricity, but the value of that extra generation depends on whether you can use it or receive a worthwhile payment for exporting it. A proposal should distinguish between power used in the home and surplus electricity sent to the grid.
If your household has a smart meter, ask whether recent usage data can inform the design. The timing of use matters: a home that consumes more electricity during daylight may use more solar generation directly, while a household that is often empty during the day may export a larger share unless it shifts flexible activities or adds storage. Don’t accept a system size solely because it is described as the most popular option.
Ask for a roof plan showing panel placement and any areas excluded because of shade, roof features or access needs. Confirm that the company has considered the roof’s condition and whether repairs might be sensible before installation. Putting panels on a roof that will soon need significant work can add avoidable cost and disruption.
For a home with more than one roof direction, ask how the different sections affect the expected generation and equipment design. The installer should state the assumptions used in its estimate and explain how shading or a change to the proposed layout would affect it. If a site inspection is needed to confirm measurements or electrical work, find out whether the quote is conditional on that assessment.
Panels generate electricity; the inverter converts it into a form your home can use. A quote should identify the equipment models rather than leave you to compare brand names alone. Ask how the inverter suits the proposed array, whether it can support a future battery and what happens if a component needs replacement.
A battery is an option, not an automatic requirement. It may suit a household that wants to store daytime generation for later use or prioritises backup power, but its value depends on usage patterns, electricity tariffs, export terms and the added purchase and installation cost. Ask for estimates both with and without a battery, using consistent assumptions, so you can judge the trade-off.
If backup during an outage matters, clarify exactly what the system can power. A grid-connected solar system does not necessarily keep supplying a home when the grid is down. Battery backup depends on the system design, and it may cover only selected circuits rather than every appliance. Have the installer specify which circuits are included and what limitations apply.
Equipment is only part of the purchase. Ask who will perform the installation, who supervises subcontractors and who is accountable if the finished work differs from the proposal. Confirm that electrical work will be completed and documented by an appropriately registered electrical worker, and ask what completion and compliance documents you will receive.
For a grid-connected system in New Zealand, the project may involve a connection process with your local lines company. Requirements can depend on the network and system design. Ask the installer who will make any required application, whether the quoted price includes that work and what you need to do before the system is switched on. A company that understands the local process should be able to explain its role without promising an approval it does not control.
Aftercare deserves the same attention as installation. Ask for one named service contact and a clear process for reporting a fault. Find out whether the installer, equipment supplier or another business handles each type of issue. If the company stops trading or changes ownership, ask what support remains available and how product warranties are claimed.
Solar proposals can include several different kinds of warranty. Product coverage applies to equipment; workmanship coverage relates to installation; and performance terms, where offered, concern output under specified conditions. These are not interchangeable. Request the written terms for each, including exclusions, claim steps and which company is responsible.
Check what happens if a component fails outside the product warranty, or if diagnosing a fault involves labour, travel or removing and reinstalling equipment. Ask whether the installer will help coordinate a manufacturer claim. The aim is not to assume a failure will occur, but to understand the practical support available if it does.
If you are considering finance, compare the total amount payable rather than focusing only on a regular repayment. Check the interest rate, fees, term, early-repayment conditions and whether the solar system is tied to another product or service. Ask for a cash-price quote as well as the financed offer. A payment plan can make the initial cost manageable, but it does not by itself make the system a good investment.
Ask each company to show how it estimated your likely bill savings. The calculation should make clear what it assumes about system output, household consumption, electricity prices, export payments and battery use. If the proposal claims the system will pay for itself within a particular period, request the calculation and ask how the result changes if those assumptions do not hold.
Compare the estimated value of electricity used at home with the value of electricity exported. Retailers set their own terms, and export payments may differ from the price you pay to buy power. Confirm the applicable terms with your electricity retailer before using them in a financial comparison. Also ask whether the estimate accounts for ongoing costs or simply compares the installation price with projected bill reductions.
Do not assume a grant, rebate or other incentive applies. If a proposal includes one, ask the company to identify it, explain eligibility and show whether the price or payback estimate depends on receiving it. Verify the terms before signing rather than treating an incentive in a sales presentation as guaranteed income.
One concern does not automatically disqualify a provider, but unresolved questions should be settled before you commit. The best solar companies can explain both the benefits and the limits of the system they are proposing.
Not without checking that the quotes cover the same equipment, installation work and support. A lower price may exclude important work or offer a different system design. Compare the written scope and total cost, then ask about any unexplained gap.
A single provider can make it easier to coordinate design, installation and support, but it is not automatically the better deal. Compare the equipment, battery operation, warranty responsibilities and total price. If you may add a battery later, ask whether the proposed inverter and system can accommodate that plan.
Ask the installer to relate the proposed size to your electricity use, roof layout and expected daytime consumption. The quote should explain the expected generation and what share may be used at home or exported. A system that produces more is not necessarily a better fit if the extra output has limited value to your household.
Not necessarily. A grid-connected system may shut down during an outage, and backup usually depends on a battery and suitable system design. Ask the installer to list the circuits that would receive backup and any limits on how they can be used.
Keep the signed contract, final equipment list, warranty documents, electrical and commissioning records, and any network-related documents supplied for the project. Ask the installer to explain how to monitor the system and whom to contact for service. Store financing documents separately so the system’s cost and repayment obligations remain clear.
The best solar companies make the decision easier by showing how their design fits your roof, electricity habits and plans, then backing it with clear installation, warranty and cost information. Compare like-for-like written quotes, check assumptions behind savings and confirm who will handle each stage. Choose the proposal you understand and can verify, not simply the one with the lowest headline price.
