Small wind turbine estimator

Wind is the most romanticized and most disappointing power source in off-grid life, and the gap between the two comes down to one physical fact: power rises with the cube of wind speed. This calculator applies the standard small-wind estimate honestly, then tells you plainly whether your site is one of the few where a turbine earns its tower.

The cube law, and why averages lie

Double the wind speed and the power available multiplies by eight. Run that backwards and it explains most wind heartbreak: a site averaging 8 mph has barely half the energy of one averaging 10, and a quarter of one averaging 12.7. People remember their windiest days and buy for those; the turbine lives at the average. Most inland, tree-sheltered homesteads average 5 to 8 mph at tower height, which produces almost nothing, and no turbine brand can repeal the physics.

Get a real number before spending anything: airport climate data, state wind resource maps, or best of all a season with a recording anemometer at the height you would actually mount. If the honest average is under 8 mph, the verdict row will say so, and the same dollars in panels via the solar calculator will make several times the energy.

Height and clear fetch beat everything else

Wind near the ground is slow and turbulent, and turbulence is wear, not watts. The working rule is 30 feet above anything within 300 feet, and every extra 20 feet of tower typically adds more annual energy than a bigger rotor would. A tall tower over open fetch with a modest turbine outperforms a big turbine on a short pole behind trees every single time. Budget honestly: the tower, wiring run (size it with the wire gauge calculator), and concrete often cost as much as the turbine itself.

Where wind genuinely earns a place

Wind's gift is its schedule: it blows at night and blows hardest in the storm-and-winter months exactly when solar sags. On a truly windy site, ridgelines, plains, coasts, a small turbine paired with solar flattens the year beautifully and shrinks the battery bank both would otherwise need, which you can sanity-check with the battery runtime calculator. If you have falling water instead of moving air, run the micro-hydro calculator first, a fraction of the watts running around the clock beats both.

Maintenance is the last honest note: turbines are machines on a pole in the weather, bearings, blades, and brakes need attention solar simply never asks for. The Solar & Power archive covers hybrid system design and what a realistic wind-solar pairing looks like when the site deserves one.

Getting a useful answer out of this

Wind turbine estimator returns monthly production, average continuous watts, same energy from solar, and straight talk. Every one of those is a planning figure rather than a specification: it tells you the size of the problem and roughly what it will take to solve, which is what you need before you can shortlist equipment or ask a supplier a sensible question.

The single most useful habit with any calculator on this site is to run it more than once. Change one input at a time and watch which output moves. That tells you where your design is sensitive, and design sensitivity is far more valuable than a single answer, because it identifies the assumption worth spending real effort to pin down. If a modest change in one input swings the result substantially, that input deserves a measurement rather than an estimate.

It is also worth running the pessimistic version. Off-grid systems are sized by their worst case rather than their average, and a design that only works on the numbers you hoped for is a design that works for part of the year. Put in the colder temperature, the longer run, the larger household, the dimmer month, and see whether the answer is still one you can live with.

What a calculator cannot know

Any tool like this works from the inputs you give it and from published averages for everything else. It does not know your particular site, the way your household actually behaves, the corner your building was cut in, or the ten-year-old equipment already installed that does not match its datasheet. Treat the output as a well-informed starting bracket, not as a specification to order against.

Three things in particular sit outside what any of these tools can see. The first is local rules, which decide what you may build regardless of what the arithmetic says: the laws pages cover those by state, county, and town. The second is the condition and quality of what you install, which is why two identical designs perform differently. The third is how the system is wired and protected, which decides whether it is safe rather than whether it is adequate, and which is the subject of lesson six.

Where a number here comes from a constant or a rule of thumb, the method notes above say so and give the source. That is deliberate: a result you cannot check is a result you should not act on, and the arithmetic here is simple enough to verify by hand on paper if you want to.

Where to take the answer next

A single figure rarely settles anything on its own, because off-grid systems constrain each other. The load list decides the array, the array decides the controller, the battery decides what the inverter can deliver, and the climate at your site decides all of it. The system planner takes one set of inputs and produces a whole coherent plan rather than an isolated number, which is usually the better next step once you have a figure you trust.

For location-specific inputs, the site report gives any address its real 30-year sun, climate, elevation, and distance figures, including the worst-month sun hours that size an off-grid system properly. For the equipment that the result points at, the spec tables list what manufacturers publish, normalised so that units of different sizes can be compared, and each product page works its own numbers through. For what things cost this month, the price index.

And for the reasoning rather than the arithmetic, the free course runs through the decisions in the order they actually arrive, from deciding whether the life suits you through to the first year on the land. Most of the mistakes that calculators cannot prevent are ordering mistakes, made before anyone opened a calculator at all.