Battery & Cost Tools

Compare Solar System Configurations

Input the specs for two solar system designs and get a clear side-by-side comparison of cost, energy capacity, daily output, and financial performance — so you can choose the right system with confidence.

What to Compare When Choosing a Solar System

The best solar system for your situation balances upfront cost, energy coverage, and long-term value. Key metrics to evaluate side by side:

1. Cost Per Watt ($/W)

The most common metric for comparing solar installations. Divide total installed cost by total panel wattage. In 2025, residential solar averages $2.50–$3.50/W installed before incentives.

2. Cost Per Usable kWh of Storage

For battery storage, compare the cost per usable kilowatt-hour. Divide battery cost by usable capacity (rated capacity × DoD). Lithium LiFePO4 typically costs $400–$800/usable kWh; lead-acid costs less upfront but 2–3× more over a 10-year window due to replacement cycles.

3. Daily Energy Coverage (%)

What percentage of your daily load does the system cover? A system that covers 80% of daily usage is meaningfully different from one covering 100% or 120%.

4. Payback Period

Shorter payback periods with similar system size indicate better value. Compare net costs (after incentives) against annual savings.

System Size Comparison Guide

System Type	Panel Size	Battery Bank	Typical Use Case	Est. Cost
Starter Off-Grid	400–800W	100–200Ah / 12V	Cabin, weekend use	$1,500–$4,000
Small Home	2–4 kW	200–400Ah / 24V	Small home, RV full-time	$8,000–$18,000
Medium Home	5–8 kW	400–800Ah / 48V	Average home off-grid	$18,000–$35,000
Large Home	10–15 kW	800–1,600Ah / 48V	Large home, EV charging	$35,000–$65,000

Frequently Asked Questions

Should I get a larger panel array or a bigger battery bank?

It depends on your usage pattern. More panels harvest more energy on sunny days but don't help at night if the batteries are already full. More battery capacity stores more energy for nights and cloudy days but is useless without enough panels to fill it. The right balance is a panel array that can fill your batteries in 1–2 days of average sunlight, with batteries sized for 2–3 days of autonomy.

Is it better to add a second battery bank or more solar panels?

If your batteries regularly fill before sunset (charge controller shows bulk complete by early afternoon), you need more storage. If your batteries rarely fill or are depleted by morning even in good weather, you need more panels. Monitor your system for a week to identify which bottleneck you actually have before spending money.

How do I compare a 24V system to a 48V system?

Higher voltage systems (48V) are more efficient: for the same power output, current is halved compared to 24V, meaning thinner wires, less heat, and lower losses. 48V is the standard choice for systems over 3kW. The comparison tool lets you input both configurations and see the electrical and cost differences side by side.