Solar vs Wind vs Hydro Calculator — Compare Renewable Energy Options for Your Off-Grid Property

A solar vs wind vs hydro calculator compares the upfront cost and viability of three renewable energy technologies for meeting your specific daily power load. Enter your daily energy requirement, solar resource, average wind speed, and stream head and flow data — the calculator simultaneously sizes all three systems, estimates net cost after the federal tax credit, flags which technologies are viable for your site conditions, and recommends the best approach based on your specific resource profile.

How to Use the Solar vs Wind vs Hydro Calculator

Step 1 — Enter your daily energy need.

Type your total daily power consumption in kilowatt-hours. The default 20 kWh/day represents a comfortable off-grid US home running refrigeration, lighting, water pump, electronics, and moderate appliance use. A minimal off-grid cabin might need only 5–8 kWh/day. A full off-grid homestead with a washing machine, power tools, and electric cooking could need 30–40 kWh/day.

This single input drives all three system sizing calculations simultaneously — changing it instantly resizes the solar array, wind turbine, and hydro system required to meet the load.

Step 2 — Check or uncheck the Federal Tax Credit.

The 30% ITC checkbox applies to all three renewable technologies and is enabled by default. The federal Section 25D tax credit covers solar PV, small wind turbines, and micro-hydro equipment installed on a US residence — one of the few incentive programs that spans all three technologies simultaneously. Checking the box reduces all three cost estimates by 30%, allowing a direct apples-to-apples comparison of after-credit costs. Uncheck it to see gross pre-credit hardware costs.

Step 3 — Set your solar resource.

Drag the Peak Sun Hours slider from 3 to 8 hours. This is your location’s daily average peak sun hours — the standardized metric for solar productivity. Use your regional figure: US Southwest averages 6.0–7.0 PSH, California and Texas 5.5, the Mountain West and Midwest 4.5–5.5, the Northeast 4.0, and the Pacific Northwest 3.5.

The solar system is sized to produce 120% of your daily load during peak sun hours — the extra 20% accounts for battery charging inefficiency and inverter losses inherent in any off-grid solar-plus-storage system.

Step 4 — Set your average wind speed.

Drag the Wind Speed slider from 4 to 25 mph. The calculator uses your average year-round wind speed to determine both viability and required turbine size. Wind speeds below 9 mph make small residential turbines economically unviable — the calculator automatically flags this and removes the wind option from the cost comparison chart.

At 9–12 mph, wind becomes viable with a moderate capacity factor. At 15+ mph, wind turbines deliver excellent capacity factors and become competitive with solar on a cost-per-kWh basis. Find your location’s average wind speed from NREL’s Wind Resource Maps, NASA POWER database, or your nearest weather station’s long-term average data.

Step 5 — Enter your micro-hydro head.

Type the vertical drop from your water source to the turbine intake in feet. This is the static pressure driving the water through your system — called the “head” in hydro engineering. Measure it from the surface of your water source (spring, creek, or pond) down to the elevation where your penstock pipe delivers water to the turbine.

Even a modest 10–15 feet of head can be productive if combined with adequate flow. More head means more pressure, which means more power from the same flow rate. If you have no water source on your property, enter 0.

Step 6 — Enter your water flow rate.

Type your year-round available water flow in gallons per minute. This must be a conservative figure representing the minimum dry-season flow, not a peak spring flow — your hydro system must be sized for the lowest flow it will ever encounter. Measure flow by timing how long it takes to fill a known container at the intake point. A trickle of 10–20 GPM with good head can still generate meaningful power.

A spring or creek with 50–100+ GPM at moderate head can often power an entire off-grid home with power to spare. Enter 0 if you have no viable water source.

Step 7 — Read the three technology cards.

The Solar card always shows a viable result with array size, estimated net cost, and daily yield. The Wind card shows either a viable result with turbine size, net cost, and capacity factor — or a red “Low Wind Speed” flag if your average is below 9 mph. The Hydro card shows either a viable result with continuous output watts, daily yield, and net cost — or a red “Stream Too Small” flag if your head and flow combination cannot meet your daily load. If head or flow is 0, the card shows “No Water Source.”

Step 8 — Study the cost comparison chart.

The three horizontal bars compare net costs after ITC across all viable technologies. Only viable options appear in the chart — non-viable technologies are automatically hidden. Solar always appears since it is viable in any location with measurable sunlight. Wind and hydro appear only when site conditions support them. The bar lengths are proportional, making the relative cost difference between technologies immediately visible.

Step 9 — Review the technology pros and cons table.

The three-row table summarises the primary advantage, major drawback, and battery bank requirement for each technology. Solar’s zero moving parts and reliability contrast with its complete nighttime production stoppage. Wind’s 24-hour generation capability contrasts with high mechanical maintenance. Micro-hydro’s continuous 24/7 generation — the most reliable of all three — contrasts with its strict site requirement of a perennial stream with adequate head and flow.

The battery bank requirement column is particularly important for off-grid design: hydro systems need minimal storage, wind systems need moderate storage, and solar-only systems need the largest and most expensive battery banks.

Step 10 — Read the site assessment insights.

The insights section provides personalised recommendations for each of the three technologies based on your exact inputs. It flags whether your wind speed is viable, whether your hydro resource is sufficient for full load coverage or only supplemental charging, and whether you have struck “off-grid gold” with a stream that can power your home continuously without large batteries.

Step 11 — Export your comparison report.

Click Export PDF to save a printable renewable energy site assessment — useful for property purchase decisions, planning conversations with off-grid installers, or presenting technology options to a partner or lender.

The Sizing Formulas Explained

Solar array sizing: Required kW = (Daily load × 1.20) ÷ Peak sun hours Cost = Required watts × $4.00/W × (1 − ITC)

Wind turbine sizing: Capacity factor = min(0.40, (wind speed ÷ 25)³) Required kW = Daily load ÷ (24 hours × capacity factor) Cost = Required watts × $7.00/W × (1 − ITC) Minimum viable wind speed = 9 mph

Micro-hydro output: Available watts = (Head in feet × Flow in GPM) ÷ 10 Available daily kWh = Available watts × 24 ÷ 1,000 Viable if available daily kWh ≥ daily load Cost = ($3,000 base + Required watts × $2.50/W) × (1 − ITC)

Example — 20 kWh/day off-grid home, 5.0 PSH, 12 mph wind, 20 ft head, 50 GPM, ITC applied:

• Solar: (20 × 1.2) ÷ 5.0 = 4.8 kW → cost = 4,800 × $4.00 × 0.70 = $13,440
• Wind: cap factor = (12÷25)³ = 0.111 → 20 ÷ (24 × 0.111) = 7.5 kW → $36,750 after ITC
• Hydro: (20 × 50) ÷ 10 = 100W → 100 × 24 ÷ 1,000 = 2.4 kWh/day → not sufficient for 20 kWh load
• Winner: Solar at $13,440 net

Frequently Asked Questions

Q: Which renewable energy source is cheapest for off-grid living in the US?

A: For most US properties, solar PV delivers the lowest upfront cost per kilowatt-hour of daily capacity — typically $13,000–$20,000 net after the ITC for a 20 kWh/day system.

Wind turbines are significantly more expensive per unit of output for small residential-scale installations — the turbine, tall tower, specialized controller, and installation typically run $7.00–$10.00 per watt compared to $3.50–$5.00/W for off-grid solar.

Micro-hydro is the cheapest option when adequate site resources exist, because the low-cost turbine hardware takes advantage of your stream’s free gravitational energy — but only a small percentage of US rural properties have the head and flow combination required. The most common answer for US off-grid homesteaders is solar as the primary source, sometimes combined with a small wind turbine for winter supplementation.

Q: What wind speed do I need for a small wind turbine to be viable?

A: Small residential wind turbines — in the 1–10 kW range used for off-grid homesteads — require a consistent average wind speed of at least 9–10 mph to generate meaningful power at reasonable cost.

Below 9 mph, the cubic relationship between wind speed and power output makes small turbines economically unviable — power output drops by 51% when average speed falls from 10 mph to 8 mph. Above 12–15 mph, small wind becomes highly cost-effective and can significantly reduce battery bank requirements by generating power at night and during winter storms when solar output is minimal.

The best locations for small wind in the US include the Great Plains from Texas to the Dakotas, coastal New England, mountain ridgelines in the West, and the Hawaiian Islands. The NREL Wind Resource Maps at windexchange.energy.gov provide average wind speeds for any US location at various heights above ground.

Q: How do I calculate micro-hydro potential on my property?

A: The standard rule of thumb used in this calculator is: Available Watts = (Head in feet × Flow in GPM) ÷ 10.

This formula incorporates typical pipe friction losses and turbine efficiency at around 50–60% combined system efficiency. To measure head, you need the vertical elevation difference from your water source surface to the turbine installation point — a simple optical level, phone inclinometer app, or surveying transit can measure this accurately.

To measure flow, time how long a 5-gallon bucket takes to fill from your intake point — divide 300 (seconds × gallons) by fill time in seconds to get GPM. Both measurements should be taken during the driest part of the year to ensure your system is sized for minimum available resources. A property with 30 feet of head and 100 GPM can generate (30 × 100) ÷ 10 = 300 watts continuously, or 7.2 kWh per day — enough to power a minimal off-grid cabin without batteries.

Q: Can I combine solar, wind, and hydro on the same off-grid property?

A: Yes, and hybrid systems combining two or three renewable sources are often the most resilient and cost-effective off-grid design available.

The resources complement each other’s weaknesses naturally. Solar peaks in summer, wind often peaks in winter. Hydro runs 24/7 regardless of season or weather. A property with modest solar, modest wind, and a small stream might combine all three to achieve reliable year-round power with a minimal battery bank — each source covering the gaps in the others.

In practice, the most common US hybrid combines solar as the primary source with a small wind turbine for winter and nighttime generation, reducing the battery bank size by 40–60% compared to a solar-only system. Adding even a small hydro trickle charger of 100–200 watts continuous output dramatically reduces the nights and cloudy periods that require battery discharge.

Q: Does the federal tax credit apply to wind and hydro as well as solar?

A: Yes. The Section 25D residential clean energy credit covers all three technologies when installed on a primary or secondary US residence.

Solar panels, small wind turbines, and micro-hydro equipment all qualify for the 30% credit through 2032 under the Inflation Reduction Act. The equipment must be installed on your residence — a cabin or off-grid home you use as a dwelling qualifies, but a purely commercial installation does not qualify under Section 25D (it would use the commercial Section 48 credit instead).

Battery storage integrated with renewable generation also qualifies. As with all ITC claims, you must have sufficient federal tax liability to use the credit, and unused amounts carry forward to subsequent years. A hybrid off-grid system combining solar, wind, and micro-hydro components — all qualifying under the same Section 25D credit — can generate a very substantial tax credit on a single installation.