The basic chain of parts
A small solar lighting setup is a chain. Sunlight reaches a panel, the panel makes electricity, a controller manages how that electricity is delivered, a battery stores it, and the lights draw from the battery. If any link is too small, the whole chain is limited by it.
Most small DIY systems run on low-voltage direct current, commonly 12 volts, and use lights made for that voltage. This keeps the wiring simple and avoids the extra equipment needed to produce household alternating current. The other article on solar power covers the broader question of whether a shop should rely on solar at all; this one is about the parts.
The solar panel
The panel converts light to electricity. Its rating is given in watts under standard test conditions, which are better than real outdoor conditions. In practice you typically get less than the label, because of clouds, heat, dust, panel angle and the time of year.
Points to consider:
- Size. Bigger panels collect more energy. Small panels suit a single lamp, while a shop with several lights needs more.
- Location. The panel needs clear sun for most of the day. Shade from trees, a neighbor’s roof or even a chimney can cut output sharply, so choose a sunny spot, often a south-facing roof in the northern hemisphere.
- Angle and mounting. A fixed panel is usually tilted toward the sun and mounted securely so wind cannot loosen it. Mounting on a roof involves working at heights, which carries real fall risk, so follow safe ladder practice and consider whether ground mounting is more suitable.
- Cleaning. Dust and leaves reduce output. Clean gently when the panel is cool.
The charge controller
A charge controller sits between the panel and the battery. It prevents the battery from being overcharged and, in many designs, stops the lights from draining the battery too far. Both protect the battery and extend its life.
Controllers differ in how they handle the panel’s output. Simple types are inexpensive and fine for small systems; more advanced types extract more energy but cost more. Choose one rated for at least your panel’s voltage and current, with some margin, and make sure it matches your battery type.
The battery
The battery stores energy so the lights work in the evening or on a cloudy day. Common choices for small systems include sealed lead-acid and lithium-based batteries. Each has trade-offs in weight, cost, lifespan and how much of the stored energy you can use safely. Lead-acid batteries generally should not be drained deeply, while lithium types often tolerate more depth of discharge, though this varies by product and the maker’s instructions rule.
Battery capacity is usually given in amp-hours at a stated voltage. Multiplying amp-hours by volts gives watt-hours, which is the energy figure that is easiest to compare with your lights. Our article on battery amp-hours and volts explains the terms in more detail.
Safety points for batteries:
- Do not short the terminals; a dropped wrench across them can cause sparks, burns or fire.
- Keep batteries in a ventilated, dry place away from sawdust, finishing rags and solvents. Some types can release gas during charging.
- Do not charge a battery with a charger meant for a different chemistry.
Fuses and wiring
Low voltage is not the same as no risk. Batteries can deliver a lot of current, and thin or undersized wire can overheat. Common practice is to place a fuse or breaker close to the battery, sized for the wire and equipment according to the maker’s instructions, and to use wire gauge adequate for the current and distance. Keep wire runs short where you can, because voltage loss adds up on long thin runs. Use proper connectors rather than twisted bare wire, and protect the wire where it passes through walls.
A switch lets you turn the lights off without disconnecting anything. When you do need to change wiring, disconnect the panel, then the load, and cover the panel if you must work in full sun, since a connected panel in daylight is live.
The lights
Choose LED lights designed for 12 volt systems, since they use little power and run well from a battery. LED shop fixtures and strips are the usual choices. LED strips are especially common in solar setups because they draw small amounts of power and can be placed exactly where needed.
Also make sure the lights have adequate brightness for the job, which is where task lighting such as a lamp at the bench is more efficient than lighting the whole room.
A hypothetical sizing example
This example uses made-up numbers only. Real products vary, so use the labels on your own equipment.
Suppose a shop owner wants about 20 watts of LED lighting for 4 hours on a work evening.
- Energy needed per evening: 20 W x 4 h = 80 watt-hours.
- A 12 volt battery rated at 20 amp-hours stores about 12 x 20 = 240 watt-hours in total.
- If the battery is only meant to be used down to about half its capacity, then about 120 watt-hours are usable, which covers 80 watt-hours with some margin. Real systems have losses, so margin is sensible.
- If a panel produces the equivalent of about 4 hours of full-strength sun on a good day, then a 100 watt panel could in theory produce around 100 x 4 = 400 watt-hours, but real output is often much lower. Even if it were half of that, 200 watt-hours would still cover the 80 watt-hours used. On poor days or in winter, output might be a fraction of this, which is why a margin and a plan for dark days matter.
The takeaway is not the exact numbers but the method: work out how much energy the lights use, then size the battery and panel with generous margin.
Before you buy
- Add up the watts of every light, and the hours you actually use them.
- Match controller, battery and panel voltages and ratings.
- Look for clear specifications and safety markings rather than vague claims.
- Plan for the weather where you live, not the best-case day.
- Think about how you will recharge the battery from another source if the sun fails. A backup, such as a plug-in charger, is a sensible idea.
If any part of this goes beyond your comfort level, a qualified installer can help. This article is general information only.