The Real Comparison
Hydro vs solar vs wind comes down to one question: what does your land have plenty of? Sun, breeze or falling water. All three are renewable energy sources, and all three generate electricity without burning anything.
But they have completely different personalities. Solar sleeps at night, wind takes naps on calm days, and a good stream just keeps going. So which one should get your money? Here they are, side by side, one round at a time.
What Is Solar Power, Wind Power And Hydropower?
Solar power turns sunlight straight into electrical energy. The panels use a technology scientists call "photovoltaic". That's just a fancy word for a material that makes electricity when light hits it, with no moving parts at all. That's why you see solar panels on rooftops, cabins and even road signs, and why solar energy is the most accessible of the three.
Wind power uses spinning blades. The wind pushes them round, like blowing on a paper pinwheel, and a generator in the hub converts that spin into electricity. Wind energy needs open space and a steady breeze, so turbines sit on tall towers above the trees.
Hydropower uses falling water. It runs from a high spot down a pipe and spins a small turbine at the bottom, a bit like a garden hose spinning a toy wheel. The more flow and the bigger the drop, the more power you get.
Which Renewable Energy Source Costs Less Per kWh?
On a site with a strong, steady stream, hydro often comes out cheapest per kilowatt-hour, because it runs day and night and needs only a small battery. Without a stream, it is not an option at all.
The fair way to compare is total cost spread over the system's life, divided by the electricity it makes. Experts call this the levelized cost of energy.
Be careful with neat price tables online. Most come from utility-scale power plants, not a single off-grid home. For your home, the number depends on what the gear costs where you live, how much your site makes (sun hours, wind speed, or head and dry-season flow), how long it lasts, and how big a battery and backup you need.
Solar is the most predictable investment and works almost everywhere. Wind energy can be great on a truly windy, open site and poor almost everywhere else. To run the numbers for your own home, try the payback calculator and the system cost calculator, and see the full cost breakdown for home hydro. For the wind side, here is what off-grid wind systems cost.
Reliability: Day And Night vs On And Off
This is where falling water really shines.
Solar energy flows only when the sun is up, and how much depends a lot on where you live. Chicago gets about 4 "peak sun hours" a day and Phoenix about 7.5. A peak sun hour is one hour of full, bright sunlight. The rest of the day you run on batteries, so you can check your own average sun hours before you size anything.
Wind energy comes and goes with the breeze. Some sites get steady wind, but most get bursts and lulls that depend on the weather, so you need batteries for the calm spells.
A stream makes power as long as it flows. On a good site that means day and night, with less output in a dry season.
So a stream needs far less energy storage. Solar and wind typically lean on a big battery bank, while a stream system may only need a small buffer battery for the moment between switching on a kettle and the turbine catching up. Read more about how home batteries work.
Lifespan And Maintenance
Solar panels last the longest on paper. The average panel now lasts 25 to 35 years, up from around 20 years in 2007, and needs very little care. See cleaning and maintaining solar panels.
Small wind systems have an average useful life of about 20 years. With routine maintenance and new blades or bearings, some have kept running for 50 to 60 years. But wind has the most moving parts working in rough weather, so it needs the most attention. See wind turbine maintenance.
Most micro hydro turbines are expected to last at least 25 years. The work is simple: keep the intake clear of leaves and silt, check for leaks and grease the moving parts, as our home hydro maintenance guide shows.
Which Renewable Energy Option Suits Your Land?
Solar works almost anywhere. Some regions get far more sun than others, but panels produce something useful on almost every roof or patch of ground on Earth.
Wind needs a real breeze at the height of the turbine. Your site should average at least 4 meters per second (about 9 miles per hour) at hub height, which is the distance from the ground to the middle of the rotor. Plenty of places have less than that, so first check whether there is enough wind on your site.
Hydro needs a stream with a drop, and most land simply does not have it. It also takes the longest to set up: an intake, a penstock (the pipe down to the turbine), a turbine pad and a long wiring run. Many places also require a water license and other permits for home hydro.
Environmental Impact: What Is The Cleanest Source Of Electricity?
All three are clean while they run. Solar panels and wind turbines make no air pollution or greenhouse gas emissions when operating, and hydropower does not directly emit air pollutants either.
The emissions hide in the making. Panels need metal and glass that take a lot of energy to produce, but a solar system can pay back that energy within 1 to 4 years. Big dams are a different story, because reservoirs can change river temperature and flow, and some fish get hurt passing through turbines.
A small home system is usually "run-of-river". That just means it borrows some of the stream and gives it back lower down, without a big reservoir, so it has very little environmental impact. Compared with fossil fuels, all three are a big step toward a sustainable home.
What Is The Biggest Problem With Hydropower?
You need the right water, and most homeowners don't have it. Without a stream that keeps flowing and drops enough, there is no hydro at all.
Even with a stream, the flow changes with the seasons, so you'll want a year of flow data before you buy anything. Start with can your stream actually power your home? and then learn about measuring head and flow.
Which Is Better, Wind Power Or Hydropower?
On a site with a good stream, hydropower is usually the better choice, because it runs day and night and needs a much smaller battery. Wind only wins when you have no stream but a truly windy, open spot.
Wind also brings more moving parts and more upkeep, and on a weak site it makes little power for its price. If you're on the fence, read are home wind turbines worth it.
Solar vs Wind vs Hydro Pros And Cons: What's Best For Your Site?
The best renewable energy option depends on your site, so start with what your land has the most of.
You have a flat, sunny lot with no stream: solar, all the way.
You have a windy ridge with no stream: wind plus solar. Solar handles the calm, sunny days, and wind keeps going at night and in stormy spells. Here is more on wind and solar hybrid systems.
You have a stream with a real drop: hydro is often the most effective choice. It's reliable, and the small battery keeps the bill down. Add a small solar array for the dry season and you have a very strong system.
You have a stream with only a small drop or a summer trickle: probably go solar instead.
Why Stack Energy Sources
Off-grid homes often combine energy sources, because each one fails at a different time. Solar fails at night and when clouds block the sunlight, wind on calm days, and a stream in drought. When one is down, another is usually up, so you need a much smaller battery bank.
The classic off-grid trifecta is solar plus hydro plus a generator. Solar covers most of the daylight, the stream covers the nights, and the generator covers the worst dry weeks. Go deeper with solar power, wind power and the full hydro overview.
Sources
- US DOE, End-of-life management for solar photovoltaics
- US EIA, Solar energy and the environment
- US EIA, Wind energy and the environment
- US EIA, Hydropower and the environment
- US DOE, Consumer Guide to Small Wind Energy Systems
- Government of Ontario, Micro-hydro systems
- SolarReviews, What is a peak sun hour?
Hard Words
| Term | What it means |
|---|---|
| Levelized cost of energy | The total cost of a power system spread over the years it runs, divided by the energy it makes. The fair way to compare sources. |
| Kilowatt-hour ($/kWh) | The unit electricity is sold in. The total bill of a power system is often quoted as cents or dollars per kWh. |
| Photovoltaic | The kind of solar panel that turns sunlight straight into electricity, with no moving parts. |
| Peak sun hour | One hour of full, bright sunlight. Chicago gets about 4 a day, Phoenix about 7.5. |
| Battery bank | The group of batteries that bridges the gap when solar or wind is not making power. |
| Buffer battery | A small battery that smooths out sudden loads like turning on a kettle. Way smaller than a full off-grid bank. |
| Lifespan | How many years a piece of gear lasts. Solar panels about 25 to 35 years, small wind about 20 on average, micro hydro turbines at least 25. |
| Run-of-river | A water power system that borrows water from a stream and returns it lower down, without a big dam or reservoir. |
| Stacking sources | Combining two or more energy sources, so one is usually working when another is down. |
| Penstock | The pipe that carries water from the intake down to the turbine. Often buried. |
Common Questions
Which is cheapest per kWh over 30 years?
It depends on your site and how big a battery you need. On a strong, steady stream, hydro often wins because it runs day and night.
Why does a stream system need such a small battery?
The stream flows day and night, so the turbine rarely stops. Solar and wind stop for hours or days and need a big bank.
Which lasts longest?
On paper, solar panels: about 25 to 35 years. Small wind averages about 20 and most micro hydro turbines at least 25.
Which needs the most maintenance?
Wind, because its moving parts work high up in rough weather. Solar needs almost nothing, and a stream system sits in the middle.
What is the off-grid trifecta?
Solar plus hydro plus a backup generator. Each covers the gaps the others leave, so the power rarely runs out.