How to Size Off-Grid Solar Power for CCTV in NZ

An off grid solar power system for CCTV cameras must be sized from the site’s actual daily energy use, not simply the number of cameras. Add the wattage of every device that runs continuously, convert that total to watt-hours per day, then allow for winter solar production, charging and conversion losses, and the number of sunless days the site must withstand.

For a reliable New Zealand installation, design around the weakest practical solar period rather than a bright summer day. A system that appears adequate in summer can run short when lower winter sun, cloud, shade, dirt on the panel or extra night-time infrared camera demand reduce available energy.

Inventory the full site load

Start with every device supplied by the solar system. The camera is only one part of an outdoor surveillance site. Missing network and communications equipment is one of the most common causes of undersized battery systems.

Include the following where applicable:

Fixed, PTZ, thermal or multi-sensor CCTV cameras
Infrared LEDs, heaters, wipers and fan assemblies within camera housings
PoE switches, PoE injectors and media converters
Wireless bridges, access points or cellular routers
Network video recorders, edge recorders or storage devices located at the pole or cabinet
Access-control devices, intercoms, sensors and alarm equipment
Solar-system controller consumption and DC-to-DC converters
AC inverters, if any equipment cannot operate from the system’s DC output
Monitoring hardware, cabinet lighting or other auxiliary loads

Record each device’s normal wattage, maximum wattage and hours of operation. A camera listed as a low-power model may draw more after dark when IR illumination activates. PTZ movement, heating and wireless transmission can also change the load profile.

Use measured consumption where possible. A datasheet power rating is a useful starting point, but it may be a maximum, an average or a value measured under conditions unlike the site. Where measuring is not possible, use the conservative figure appropriate to the operating condition you need to support.

Check how each device is powered

Power compatibility matters as much as energy capacity. A nominally 12 V solar battery does not automatically power every “12 V” camera or every PoE device.

Before calculating final capacity, confirm:

Camera input voltage and current range
Whether the camera is powered by direct DC, passive PoE or IEEE PoE
PoE voltage, power class and total switch power budget
Whether a DC-to-DC converter, PoE injector or inverter is required
Connector type, polarity and cable length
Start-up, PTZ, heater and night-mode peak demand
The power system’s output type, voltage, current limit and available ports

For example, a PoE switch’s own consumption and its power delivered to cameras must both be included. Do not count only the switch label wattage if the cameras draw power through it.

Convert load into daily energy

Daily energy is expressed in watt-hours (Wh). The basic calculation is:

Daily energy (Wh/day) = device power (W) × operating hours per day

Calculate each device separately, then add the results. A 24-hour security system normally has most equipment running all day and night.

Device	Planning load	Run time	Daily energy
CCTV camera	7 W	24 hours	168 Wh
PoE switch including its own load	10 W	24 hours	240 Wh
Wireless bridge	6 W	24 hours	144 Wh
Total	23 W	—	552 Wh/day

This is an illustrative load profile, not a prediction for a particular camera system. A site with two cameras, an NVR, a 4G router or high-power infrared illumination may have a substantially higher result.

For equipment that does not run continuously, use its expected duty cycle. For instance, a 20 W device operating for four hours a day uses 80 Wh/day. However, security equipment should not be treated as intermittent unless its operating schedule is intentional and acceptable for the site.

Add a realistic allowance for future equipment

Allowing for expansion during the first design is usually more practical than replacing the complete power system when another camera is added. Consider likely additions such as:

One additional camera or a camera with stronger IR
A larger PoE switch or more PoE ports
A wireless backhaul link
Cellular connectivity and remote management hardware
Extra storage or edge processing

Rather than guessing a universal percentage, add the expected future equipment to the same watt-hour calculation. This produces a clearer, auditable design basis.

Account for solar resource and losses

A solar panel’s watt rating is not its daily energy output. The energy it can harvest depends on solar resource, orientation, tilt, shading, weather, temperature, panel cleanliness and electrical losses.

For New Zealand CCTV sites, use the solar resource for the actual site and panel plane, with special attention to the lowest-production period you intend the system to cover. A north-facing array is generally the starting point in New Zealand, but roof geometry, pole layout, security, wind exposure and nearby obstructions may require a different arrangement.

The useful planning relationship is:

Required panel rating (W) = daily load (Wh/day) ÷ (peak sun hours × total system efficiency)

Peak sun hours are a way of expressing daily solar energy as equivalent hours at full panel output. Use a site-specific figure for the relevant season, not an annual average that hides poor winter performance.

Total system efficiency should allow for:

MPPT or charge-controller losses
Battery charging and discharging losses
DC-to-DC conversion or inverter losses
Cable losses, especially on long pole or cabinet runs
Panel temperature and soiling
Mismatch between ideal panel conditions and real-world irradiance
A practical design margin for changing weather and ageing

Using the earlier 552 Wh/day example, assume a conservative design solar resource of 3 peak sun hours and an illustrative total efficiency of 0.70:

552 Wh/day ÷ (3 × 0.70) = approximately 263 W of panel capacity

That result does not mean a 263 W panel guarantees operation. It demonstrates why matching a panel to battery capacity alone is not enough. A proper design must also consider whether the array can restore the battery after several low-sun days and whether physical shading changes through the year.

Treat shade as a design issue, not a minor loss

Even partial shade from trees, buildings, antenna structures or a neighbouring pole can sharply reduce solar harvest. Inspect the site across likely sun paths where possible. A clear view at midday does not prove the panel will remain clear in the morning, afternoon or winter.

For remote sites, also account for access. A panel that cannot be safely cleaned or inspected may need more margin than an easily maintained installation.

Choose battery autonomy

Battery autonomy is the number of days the battery can support the load with little or no useful solar input. The appropriate target depends on the consequence of lost surveillance, seasonal weather risk, access difficulty and the time available to restore service.

Calculate nominal battery energy from:

Nominal battery capacity (Wh) = daily load (Wh/day) × autonomy days ÷ (planned usable battery fraction × battery-to-load efficiency)

The planned usable battery fraction should reflect the battery-management settings and operating limits specified for the chosen system. Do not assume that all nominal battery watt-hours are available for routine use. Battery-to-load efficiency must also account for any converter or inverter between the battery and the equipment.

Using the 552 Wh/day example, with one day of autonomy, a planned usable fraction of 80% and 90% battery-to-load efficiency:

552 ÷ (0.80 × 0.90) = approximately 767 Wh nominal battery capacity

For two days of autonomy under the same assumptions, the nominal requirement becomes about 1,533 Wh. This illustrates the effect of autonomy: it can drive battery sizing beyond the needs of an ordinary sunny-day calculation.

Consider temperature and site conditions

Battery performance and charging behaviour change with temperature. Confirm the permitted charging and discharging conditions for the selected battery system, particularly for exposed locations with cold winter mornings or hot, unventilated cabinets.

Also plan for:

Coastal salt exposure and corrosion risk
Wind loading on panels, poles and cabinets
Water ingress protection appropriate to the installation
Ventilation and heat build-up in outdoor enclosures
Theft resistance and physical access
Lightning, surge protection and earthing designed for the site
Safe isolation, fusing and cable protection

These factors do not change the watt-hour equation, but they can determine whether an otherwise sound calculation works reliably in service.

Compare 192Wh to 1280Wh CCTV solar-system examples

The following Maxsol systems provide documented panel-and-battery capacity points for comparison. They are selection examples, not guaranteed CCTV runtimes. Actual runtime depends on connected load, solar input, battery operating limits, losses and local conditions.

System example	Documented solar panel	Documented LiFePO4 battery	Useful comparison point
CS3015 30W, 15Ah, 192Wh solar system	30 W monocrystalline	12.8 V, 15 Ah, 192 Wh	Small-capacity reference for very low-energy DC loads
CS6030 60W, 30Ah, 384Wh solar system	60 W	12.8 V, 30 Ah, 384 Wh	Mid-range reference where calculated demand and site sun support it
CS12060 120W, 60Ah, 768Wh solar system	120 W	12.8 V, 60 Ah, 768 Wh	Higher-energy reference close to the illustrative one-day battery calculation above
CS200100 200W, 100Ah, 1280Wh solar system	200 W configuration	12.8 V, 100 Ah, 1280 Wh	Largest documented capacity reference in this comparison

The CS3015 documentation specifies a 30 W monocrystalline panel, a 12.8 V 15 Ah 192 Wh LiFePO4 battery, an MPPT controller and three DC12V output ports. Those details can be useful for a low-power direct-DC design, but the camera voltage, current draw and connector arrangement must still be checked before selection.

Do not select a system by dividing battery Wh by camera W and stopping there. That shortcut ignores other network loads, usable battery capacity, peak demand, solar recharge and bad-weather autonomy. It can produce an attractive runtime number that is unsuitable for a continuously operating CCTV site.

A practical way to shortlist capacity

Use the table as a first filter:

Calculate the site’s daily load in Wh.
Calculate required nominal battery Wh for the autonomy target.
Check that the documented panel rating is sensible against the lowest-season solar calculation.
Confirm outputs, ports, voltage, current and power-delivery method.
Check whether the installation needs capacity beyond the listed examples.

A 768 Wh battery reference, for example, may look close to a calculated 767 Wh nominal storage requirement. That does not make it an automatic match: the panel may still be too small for the site’s winter energy requirement, or the equipment may have incompatible outputs or higher peak demand.

Validate before purchase

A final validation prevents the most expensive mistakes: an installation that powers up successfully but cannot maintain service through poor weather or night-time operation.

Use this checklist before specifying an off-grid CCTV power system:

Load schedule: List every device, its normal and maximum watts, and operating hours.
Night load: Include IR, heaters, PTZ movement and other darkness-related demand.
Power architecture: Confirm direct DC, passive PoE, standards-based PoE or AC requirements.
Peak load: Confirm inrush current and simultaneous peak demand, not only average watts.
Battery basis: Set autonomy days and verify the usable capacity assumptions.
Solar basis: Use the site’s low-season solar resource and account for orientation and shade.
Losses: Include controller, battery, wiring, converter and inverter losses where present.
Recharge recovery: Check whether the panel can both run the daily load and recover battery energy after a low-sun period.
Cable design: Check voltage drop, conductor size, fusing, isolation and protective routing.
Environmental design: Check temperature, wind, corrosion, water exposure and maintenance access.
Future capacity: Add planned cameras, PoE ports and communications equipment to the calculation now.
Installation requirements: Have electrical and structural work assessed and completed by appropriately qualified professionals for the site.

Common sizing mistakes to avoid

Using an annual solar average. Winter and prolonged overcast conditions are usually more important than annual production when CCTV must operate continuously.

Ignoring the PoE network. A camera may be modest in power, while the switch, wireless bridge and conversion losses materially increase daily energy use.

Assuming battery label capacity equals usable runtime. Nominal Wh is a comparison value, not a promise that every watt-hour can be drawn at the connected load.

Sizing only for average demand. Cameras may use more power at night, and maximum demand matters when selecting output capacity and protection.

Adding an inverter unnecessarily. Inverters introduce conversion losses. Where equipment can use an appropriate DC supply, a DC architecture may simplify the energy budget; compatibility must still be verified.

Overlooking shade and dirty panels. A small obstruction or neglected panel can defeat an otherwise reasonable paper calculation.

FAQ

How many solar watts does one CCTV camera need?

There is no fixed answer. Calculate the camera’s daily Wh, include the power equipment that serves it, then divide by the local low-season peak sun hours and a realistic total-efficiency factor. A single 24/7 camera may also need a PoE switch, wireless bridge or router, so the system load can be much higher than the camera rating alone.

How much battery backup should off-grid CCTV have?

Choose autonomy according to the site’s criticality, weather exposure and maintenance access. One day may be a starting point for some accessible locations, while isolated or high-consequence sites may require more. The battery must be sized from daily Wh, target days and its planned usable capacity rather than by camera count.

Can a 12.8 V battery power PoE CCTV cameras directly?

Usually not without checking the complete power path. Many PoE cameras require a PoE injector or switch that supplies a different voltage and follows a particular power method. Confirm the camera’s PoE requirement, the injector or switch input requirements, conversion losses and the solar system’s DC outputs before specifying equipment.

A sound off-grid CCTV design begins with measured or conservative load data and a low-season solar calculation. Compare the linked Maxsol models against your required port count, load, distance, power method, environment and management requirements before making a final selection.