Solar and 4G cameras: planning a site with no power and no cable

Start with watt-hours, not with the panel

Everything on a solar site is decided in watt-hours. A 12 V 30 Ah battery stores about 360 Wh in theory; usable capacity is less, because a lithium pack is normally run between 10 and 90 percent state of charge. That gives roughly 290 Wh to spend between charges. A camera drawing 5 W on average spends 120 Wh in a day, so the pack alone covers a little over two days before the sun has to help.

The panel has to replace what the camera spends, and it only works for part of the day. A 60 W panel in a place with four peak sun hours produces about 240 Wh a day, which covers a 5 W continuous load with a small margin. In a place with two and a half peak sun hours, the same panel covers 150 Wh, and the margin disappears in bad weather.

The 4G side is a data bill, not a radio

A 1080p stream at 2 Mbps costs about 21 GB a day if it runs continuously. Nobody runs a solar camera that way, which is why the modes matter: record on motion and upload clips, or keep a low frame rate and pull a snapshot on demand. Either way, work out the monthly volume before choosing a SIM plan, and check whether the camera can send an alert without waking the whole stream.

• Continuous 1080p at 2 Mbps: about 21 GB per day, 630 GB per month.
• Motion-only with 30 clips a day at 20 s and 2 Mbps: about 150 MB per day.
• A daily snapshot and a heartbeat message: a few megabytes per month.

Placement decides whether the maths works

A panel that is shaded for two hours at midday loses more than the two hours: the array works as a series string, so one shaded cell pulls the whole string down. Keep the panel clear of new buildings, tree growth and the camera's own pole shadow. Face it toward the equator, tilt it within about 15 degrees of the local latitude, and angle it so rain rinses the glass rather than pooling dust.

Cold helps the electronics and hurts the battery. Lithium iron phosphate keeps most of its capacity at -10 C and loses more at -20 C, so a site that expects a hard winter needs either a larger pack or a heated enclosure. Heat is the other direction: a panel and battery in a sealed box in the sun can sit far above ambient, which shortens pack life.

What usually goes wrong in the first winter

• Battery sized on the annual sun average instead of the worst month.
• Panel mounted flat to look tidy, collecting dust and losing output.
• No low-voltage cutoff, so the pack is deep-cycled to death.
• Data plan sized on the trial month, when recording was still off.
• Antenna run to the camera without checking signal at the actual pole position.

Ask for the panel, battery and load figures as a calculation you can check, not as a claim. A kit described as 4 days of autonomy should come with the watt-hours behind that number.

What to send for a quote

Give the country and nearest city, because peak sun hours come from the location and not from the product. Add the number of cameras, whether they record continuously or on motion, the height they will be mounted at, and whether a SIM card is already available or has to be supplied. With those four items a kit can be quoted against the worst month instead of the best one.