Solar for a shed or workshop

If your shed has a subpanel, or a buried feeder from the house, or 240-volt outlets, treat it as a workshop. Its loads are part of your utility bill, and solar for it is about offsetting that bill. The panels don’t have to be on the shop roof, and the shop doesn’t need its own battery. It just needs to be on the same meter as the array.

If the shed has no wiring, and running a trench from the house doesn’t appeal, you’re in kit territory: a 100- to 200-watt panel, a charge controller, a small battery and 12-volt LED lights. That setup runs lights, a fan and phone or tool-battery charging for a few hours a day. It will not run a table saw, a heater or a compressor, and no honest seller will tell you otherwise.

Shop tools are surge-heavy and short-duty. A 240-volt welder can pull a large current for a few seconds at a time; a 5-horsepower compressor draws roughly 3.5 kW while pumping and nothing while idle; a table saw or dust collector is 1–2 kW while running. Over a month, a hobby shop used evenings and weekends often adds only 50–150 kWh to the bill, which is a modest solar target.

Heat is the exception. Electric unit heaters in an uninsulated Colorado shop run 3–5 kW for hours, and a shop heated electrically through a Front Range winter can use more electricity than the house. If you heat the shop with electricity, tell us; it changes the system size a lot. A mini-split heat pump cuts that load dramatically and is worth pricing alongside the solar.

Because the array is grid-tied, it never has to cover a startup surge. The welder’s pulse comes from the grid; the panels offset the kilowatt-hours over the year. That’s why a shop rarely needs a bigger array than its annual kWh implies, and why a battery is only necessary if you want the shop to work during an outage.

Shop roofs are usually simple gables or single slopes, often metal, and often newer than the house roof, which makes them good candidates. If the shop’s subpanel and feeder are adequately sized, the inverter output lands in the subpanel and flows back to the house main. If not, we run a new conduit, and if we’re trenching anyway we size it for a future charger or a bigger feeder.

Low, small sheds have a snow problem the house doesn’t. A roof six feet off the ground on a north-shaded side of the lot can hold snow for weeks after a storm. We look at pitch, height and shading before recommending the shop roof, and we’ll say so when the house roof or a ground mount is the better site.

For an unwired shed, a small kit is the right answer and it isn’t expensive: a 100-watt panel, a 10-amp charge controller, a 50–100 amp-hour battery and LED lighting typically run roughly $150–$500 all in; prices vary widely by battery chemistry and quality. Mount the panel on the south-facing roof slope or a post where it gets sun; a panel that sees the sun for three hours a day at the back of the lot will disappoint.

Expect it to power what it’s built for: lights for a couple of hours a night, a small fan, a radio, a USB charger. Colorado winter cuts a 100-watt panel’s daily output to a few hundred watt-hours, so a battery that runs down in December is normal, not broken. Keep lead-acid batteries off the concrete floor and out of deep cold; lithium tolerates cold discharge better but shouldn’t be charged below freezing.

No permit is generally needed for a self-contained low-voltage kit that never touches house wiring. The moment you want a 120-volt outlet in that shed, run a proper circuit from the house instead. It’s safer, cheaper over time, and then any solar you add offsets it automatically.