If you’re weighing up solar for your home or business, you are likely wondering: how many panels do I need on my roof? The answer can change significantly based on your electricity usage, the panels your installer uses, your roof, and your goals for going solar. Below, we’ll walk through each factor, share three common system size examples, and highlight why choosing the right installer is so important for getting your system sized right the first time.
The 5 big factors that drive your panel count
1) Your electricity use
Your last 12 months of electricity use is the best starting point, and at Lightforce Solar, we will always look at this when considering your installation size. Across New Zealand, the average household uses roughly 7,000 to 7,100 kWh per year, but your number may be higher or lower depending on home size, occupants, heating, EV charging, and hot-water use.
Check New Zealand household electricity consumption data at Power Compare.
powercompare.co.nz
A higher yearly power consumption will mean you need more panels on your roof to see the power savings and export returns you might be expecting out of your system.
2) Panel wattage and efficiency
Modern residential panels in NZ commonly range from ~400 W up to ~505 W per panel, which means you can achieve the same total system size with fewer panels than a few years ago. For example, Lightforce Solar offers Trina Vertex S+ 505 W panels, with industry-leading 25-year product, and 30-year performance warranties.
A higher per-panel wattage reduces the number of panels you’ll need on your roof, and is a good sign that you are getting the latest, and highest quality panels. While panel quality in New Zealand is typically good, it is important to use a reputable installer or research the model being installed to make sure you are getting a high quality panel that will output a high wattage for years to come.
3) Roof orientation, tilt, and shading
- Orientation: In NZ, north-facing roofs produce the most energy. East and west work too – expect slightly lower annual yield, but often better spread across morning and late afternoon. Learn about solar panel orientation and roof suitability from EECA (Energy Efficiency and Conservation Authority).
- Tilt: Most typical roof pitches work fine. Flat roofs may need tilt frames, which can add cost. Read EECA’s guidance on roof tile and solar panel installation considerations.
- Shading: Even small, recurring shadows from chimneys or trees can disproportionately reduce string output. Design choices made by your installer like stringing, module-level power electronics, and smart inverter algorithms help, but the best fix is careful placement to minimise shade. Understand how shading affects solar output with guidance from Fronius Learn how shading impacts solar panel performance and how to mitigate it from Green World Energy.
Lightforce Solar will work with a real model of your roof, and historic sunlight data to ensure your system lives up to its potential (no solar shock), and will be generated when you need it.
4) Your local sunshine
New Zealand’s solar resource is strong by global standards. Our layout and output planning tools give a highly accurate view on your expected production for your exact location and panel orientation, including local terrain masking, we can show you a few simulated installations and help you understand your options for panel counts and locations to make the most of your specific property. More usable sunshine means fewer panels are needed to deliver the same annual energy output and savings.
5) Your goals – offset, savings, backup, or EVs
Maximising bill savings: Size to match daytime loads first, then consider modest oversizing to improve self-consumption and export value. Read EECA’s guidance on sizing your solar system to maximise bill savings and self-consumption.
Offsetting most of your annual use: Typically a larger array, possibly paired with a battery to shift solar to evenings. Find out how Lightforce Solar battery storage systems can help you shift solar energy to evenings and offset your annual use.
Backup resilience: Add a hybrid inverter and battery to keep essentials running during outages. Explore Lightforce Solar’s hybrid inverter and battery solutions to keep your home running during outages.
EV charging: Higher generation, smart charging, and potentially more panel area or a SolarPort solar carport to add capacity and simple charging when roof space is limited. Discover the Lightforce SolarPort – a solar-powered carport designed for EV charging and extra generation when roof space is limited.
Three popular system sizes – who they suit, and how many panels
The exact outputs vary with your roof, location, and shade. We confirm with detailed modeling using real irradiance data. Explore long-term solar production estimates using the Global Solar Atlas.Access NIWA SolarView for location-specific sunlight and shading data in New Zealand.
1) ~5 kW system – 10 to 12 panels at ~445 to 505 W each
Best for: Smaller homes, couples, or energy-savvy households with ~5,000 to 5,500 kWh per year, good daytime usage, and limited roof space. Often a strong value entry, with optional battery later. See New Zealand household energy use statistics on Figure.NZ. View Lightforce Solar’s home solar system options including entry-level packages.
2) ~6.6 kW system – 10 to 15 panels at ~445 to 505 W each
Best for: Average Kiwi households using ~6,500 to 8,000 kWh per year, families with heat pumps, or light EV charging. A sweet spot for self-consumption plus healthy export in summer, and a natural match for an entry battery.
3) ~10 kW system – ~10 to 24 panels at ~445 to 505 W each
Best for: Larger homes, multi‑generational families, high users with pools, workshops, or frequent EV charging, and homes planning a substantial battery for backup. Also common for lifestyle blocks, and small commercial sites. Learn how Lightforce Solar designs large residential and commercial solar systems.
Case study – Scott Barrett’s Lightforce installation
All Blacks captain Scott Barrett chose Lightforce Solar for his Christchurch home, prioritising lower power bills, energy security, and future‑proofing. His pack includes:
- 26 x 505 W panels
- 10 kW Sigenergy single‑phase inverter
- Sigenergy single‑phase backup gateway
- 24 kWh Sigenergy battery
- 7 kW AC EV charger
This configuration supports high self-consumption, significant storage for night-time use and outages, and EV charging – a great example of a performance‑oriented home system. Read the full story of Scott Barrett’s Lightforce Solar installation and explore Scott’s Super Solar Pack.
Why Lightforce Solar is a great choice for getting your panel count right
In‑depth consultation that starts with your data
We begin with your actual usage, your roof’s geometry, and your goals – bill savings, resilience, exports, or EVs – then size accordingly. Lightforce Solar installs thousands of systems across NZ and uses only tried-and-tested products with long warranties, so recommendations are grounded in NZ conditions and supply reality. Start your solar journey with a free, no-obligation consultation from Lightforce Solar.
Sophisticated usage and export modeling
We use advanced monitoring platforms and modeling to estimate production, daytime self‑consumption, and export potential, then recommend the right inverter, battery, and control strategy. Post‑install, all Lightforce systems include monitoring options to help you optimise performance over time. Explore Lightforce Solar’s hybrid inverter range to find the right energy management solution for your home.
Panel positioning informed by real sunlight data, and 3D models of your property
We combine national and address‑specific solar datasets – including the Global Solar Atlas for long‑term PV potential, and NIWA SolarView for local topography and sun-path shading – to place and string panels for maximum yield, while avoiding mid‑day shadows that cause outsized losses. Where helpful, we model the roof in 3D to fine‑tune array layout, tilt, and spacing. Access New Zealand-specific solar potential data on the Global Solar Atlas. Explore NIWA SolarView for accurate local sun-path and terrain shading data.
High‑quality panels, inverters, and warranties
We specify high‑efficiency, N‑type, dual‑glass panels – like Trina Vertex S+ at 445 W and 505 W – backed by 25‑year product, and 30‑year performance warranties. We pair them with proven hybrid inverters and batteries, giving you reliable generation now, and a pathway to add storage or EV charging later. View the full Lightforce Solar panel range, including the Trina Vertex S+ panels.
Shading‑aware design and mitigation
Because partial shading can significantly impact output, our designers optimise stringing, consider module‑level power electronics where appropriate, and place arrays to avoid recurring shadows – all informed by shade studies and manufacturer best practice.
Putting it together – a quick sizing roadmap
- Collect your numbers: 12 months of kWh, roof photos or plans, future changes like EVs or heat pumps. Check New Zealand household energy use statistics on Figure.NZ.
- Check your roof: North works best, east-west can be fine, and avoid recurring shade. Read EECA’s guidance on roof orientation and solar suitability for NZ homes.
- Pick a target: Offset a percentage of your annual kWh, or size for daytime savings, backup, or EV needs. Explore Lightforce Solar’s home solar systems to find the right target system for your goals.
- Choose panels and inverter: Higher-wattage, high‑efficiency panels reduce count, and hybrid inverters keep your battery options open. View Lightforce Solar’s solar panel and hybrid inverter range to find the right combination for your home.
- Model before you buy: Use site‑specific irradiance and shading tools to confirm expected kWh, self‑consumption, and export. Access long-term solar potential data on the Global Solar Atlas and explore NIWA SolarView for precise local irradiance and shading data for your address.
FAQs
Is my house sunny enough for solar?
Most Kiwi homes are. The key is a roof that gets good midday sun with minimal shading. North‑facing is ideal, but east-west can still deliver strong returns, especially when you’re home mornings or late afternoons. We confirm with NIWA SolarView and array modeling.
Read EECA’s advice on solar suitability for New Zealand homes. Explore NIWA SolarView for precise sun-path data for your location.
How many panels fit on a typical roof?
It depends on clear roof area, ridges, vents, and setbacks. Using ~445 to 505 W panels, a 6.6 kW array is often 13 to 15 panels, while 10 kW is ~20 to 24 panels, adjusted to your layout.
Talk to Lightforce Solar about how many panels will fit your specific roof with a free assessment.
What if I have some shade?
We first try to avoid or minimise it through placement. If unavoidable, we can design strings, consider optimisers or microinverters, and use inverter algorithms that hunt for the best power point under shade.
Learn how Fronius inverter technology handles shading to protect your solar output.
Will a battery change how many panels I need?
A battery doesn’t increase panel count by itself, but it lets you store more of your daytime solar to use at night, which can improve payback and resilience. If your goal is to run more overnight from solar, adding some extra generation on the roof plus a battery is a strong combo.
Ready to find your exact panel count?
Lightforce Solar’s in‑depth consultation, data‑backed modeling, and high‑quality components are designed to deliver the right number of panels in the right places – for the savings, resilience, and EV charging you want. If you like the look of Scott Barrett’s performance‑oriented setup, or you want a tailored design for your home, we’ll model your usage, your roof, and your sunshine, then present a clear plan with expected generation, exports, and payback.
Next step: Would you like me to size an initial 3-option proposal – 4 kW, 6.6 kW, and ~10 kW – based on your latest monthly kWh, your roof orientation, and whether you plan to add a battery or EV in the next 12 months? I can tailor the panel counts, expected annual kWh, and bill savings to your place, and include a Scott Barrett-style premium option, too.