What is a load profile for solar?

A load profile shows your hour-by-hour electricity consumption through the day. For solar sizing, it reveals how well your consumption patterns match solar production hours (roughly 9am-4pm). Loads that run during solar hours self-consume solar power; loads at night require grid power or battery storage.

What is load shifting for solar?

Load shifting means scheduling flexible electricity loads (EV charging, water heater, dishwasher, laundry) to run during solar production hours. This increases your solar self-consumption from 30-40% to 60-70% without adding battery storage, maximizing the value of your solar investment.

Load Profile Calculator

Build your 24-hour load profile, find peak demand, and see exactly how your solar system matches your consumption pattern.

How to Use This Calculator

Enable and configure your appliances

Check the box for each appliance in your home. Set its wattage (the actual running wattage, not the label maximum), start time, and end time. The refrigerator runs 24/7 at partial load; large appliances like the dryer or water heater run for specific hours. Use your best estimate — the goal is an approximate profile, not laboratory precision.

Read the load profile chart

The bar chart shows your hourly electricity demand (amber/green bars) vs a reference 8 kW solar system's output (teal bars). Hours where solar covers your load are shown in green; hours where you'd need grid power or battery backup are amber. This visualization shows your solar "match" — how well your consumption pattern aligns with solar production.

Interpret the solar strategy

The solar surplus hours listed below the chart show when your solar would be exporting to the grid or charging batteries. If most of your high loads fall outside solar production hours (morning showers, evening cooking, nighttime EV charging), battery storage becomes more valuable — it lets you shift solar surplus to cover those evening loads.

The Formula

Hourly load (W, hour h) = ∑ appliance watts if appliance runs during hour h Daily kWh = Average hourly load (W) × 24 ÷ 1,000 Peak demand (kW) = Max hourly load ÷ 1,000 Monthly kWh = Daily kWh × 30 Annual cost = Daily kWh × 365 × electricity rate Solar reference (8 kW system): Solar output (W, hour h) = sin(π × (h − 6) / 12) × 8,000 × 0.9 (bell curve peaking at solar noon, zero before 6am and after 6pm)

The solar production curve is a simplified model showing the general shape of solar output through the day. Actual production depends on your system size, location, panel orientation, and weather. Use our Solar Panel Output Calculator for location-specific production estimates.

Peak demand matters for utility rate structures with demand charges (common for commercial customers). Residential customers in most US states pay only for energy (kWh), not demand — but time-of-use (TOU) rates make peak hour pricing significant.

Example

Average family home — load shifting strategy

A family of 4 with central AC, electric water heater, washer/dryer, and an EV charger has a challenging load profile for solar: high morning demand (water heater, washer), midday AC, and evening/night loads (EV charging, dishwasher, TV).

Daily energy consumption45 kWh/day

Peak demand9.2 kW (at 7am)

Solar surplus hours10am–3pm

Grid-dependent hours6am–10am, 3pm–midnight

Optimal strategy

Shift water heater10am–12pm (solar hours)

Shift washer/dryer11am–2pm (solar hours)

EV charge timing11am–3pm OR add 13.5 kWh battery

After load shiftingSolar covers 70%+ of consumption

Load shifting is free — simply scheduling flexible loads (water heater, dishwasher, EV charging, washing) to run during solar production hours dramatically increases the percentage of your consumption covered by solar without adding battery storage or more panels.

FAQ

What is a load profile and why does it matter for solar? ▼

A load profile shows how your electricity consumption varies hour by hour through the day. It matters for solar because solar panels only produce power during daylight hours, peaking at midday. If your biggest loads (EV charging, water heating, cooking) happen at night or early morning, much of your solar production gets exported to the grid at low net metering rates while you import expensive evening electricity. Matching your load profile to solar production hours maximizes the value you get from your system.

What is load shifting and how does it help solar? ▼

Load shifting means scheduling flexible electricity loads to run during solar production hours (roughly 9am–4pm) rather than in the evening or morning. The most shiftable loads are: electric vehicle charging (use a timer to charge at noon instead of overnight), water heater (set a timer to heat during the afternoon), dishwasher (run after lunch), and washer/dryer (weekend daytime instead of evening). Load shifting can increase your solar self-consumption from 30-40% to 60-70% without buying batteries.

How much battery storage do I need to cover evening loads? ▼

To cover a typical evening peak (6pm-11pm) using stored solar energy, you'd need enough battery capacity to supply your average evening load. If your evening demand is 2 kW for 5 hours, that's 10 kWh of storage needed. A Tesla Powerwall (13.5 kWh) would cover most homes' evening load. For whole-home backup, use 2-3 Powerwalls or equivalent. Use our Battery Sizing Calculator to size storage for your specific load profile.

What is peak demand and do residential customers pay for it? ▼

Peak demand is the highest power draw (kW) over a billing period, typically the highest 15- or 30-minute average. Most US residential customers pay only for energy (kWh), not peak demand. However, some utilities have demand charges for residential customers, and time-of-use (TOU) rates effectively penalize peak hours with higher per-kWh prices. If you're on TOU rates, the load profile chart helps identify which hours cost the most — usually 4pm-9pm on weekdays.