Electrical reference chart
Solar System Sizing Chart
Use this worksheet after the calculator result to record load, target offset, peak sun hours, system losses, performance ratio, array kW, panel count, first-year production, year-25 production, roof fit, and utility or installer follow-up.
Quick reference table
A solar system sizing chart is a calculator-led planning worksheet. It connects monthly load, offset target, PVWatts-style losses, array size, production, roof fit, inverter, and battery assumptions before layout, interconnection, and installer review.
Solar system sizing worksheet
| Item | Record from calculator | Follow-up |
|---|---|---|
| Load basis | Monthly kWh and target offset | Confirm bill and critical loads |
| PV array | Panel count, required kWdc, and rounded kWdc | Check layout, shade, and roof area |
| Production | Average monthly, first-year annual, year-25 annual, capacity factor | Compare with PVWatts or installer proposal |
| Losses | PVWatts-style losses and performance ratio | Review shade, soiling, temperature, wiring, inverter, and availability |
| Inverter | AC rating and surge notes | Verify product and interconnection limits |
| Battery | kWh or Ah basis | Review backup loads and autonomy target |
Solar system sizing handoff
| Handoff item | Record on worksheet | Why it controls the next step |
|---|---|---|
| Load profile | Monthly kWh, target offset, critical load, seasonal peak | Array and storage choices should follow the actual load shape |
| Roof or site limit | Usable area, shade, structural or ground-mount note | Physical layout can cap panel count |
| Production model | Peak sun hours, losses, degradation, year-25 kWh | Production assumptions should stay visible before ROI or battery sizing |
| Inverter strategy | String, hybrid, microinverter, export limit | Inverter choice affects clipping, backup, and utility review |
| Battery role | Backup-only, self-consumption, outage autonomy | Battery capacity is different for each operating goal |
How to use this chart
Start with load
Record usage, target offset, critical loads, and bill period before sizing equipment.
Record production basis
Document peak sun hours, losses, performance ratio, first-year kWh, year-25 kWh, and capacity factor.
Connect PV and inverter
Document panel count, array kW, inverter rating, and clipping or export notes.
Add storage context
List battery capacity, autonomy target, backup load, and interconnection follow-up.
Formula basis
Required kWdc = target daily solar kWh / peak sun hours / performance ratio. First-year kWh = rounded kWdc x peak sun hours x 365 x performance ratio.
- Load is the monthly or daily kWh target entered in the calculator.
- Offset is the share of load planned to be served by the PV system.
- System losses are the PVWatts-style planning losses used to derive performance ratio.
- Array kW is the DC size of the module group.
- Annual degradation screens year-25 production from the first-year estimate.
- Inverter and battery values are planning inputs that need product and code review.
Worked examples
PV plus storage sizing record
Record monthly usage, target offset, PVWatts-style losses, panel count, array kW, first-year production, inverter rating, battery capacity, critical loads, and utility interconnection follow-up.
Critical-load backup handoff
Document main-panel load profile, critical-load subpanel, roof area, target offset, annual degradation, hybrid inverter rating, battery autonomy, and utility export limit before design review.
Related calculators
Solar System Design Calculator
Calculate PV array size, panel count, first-year production, degradation, and roof-area fit from monthly electricity use
Solar Calculator
Calculate solar panel energy production, cost savings, and payback period for residential solar installations
Inverter Sizing Calculator
Screen solar PV inverter AC size, DC/AC ratio range, and cold-weather string counts from module data.
Battery Capacity Calculator
Screen nominal battery-bank kWh and amp-hours from daily energy, runtime, or a peak-shaving discharge window.
Related charts
Solar Panel Output Chart
Use a solar panel output chart to document panel watts, panel count, peak sun hours, PVWatts-style losses, daily kWh, average monthly kWh, annual kWh, degradation, and offset notes.
Inverter Sizing Chart
Use an inverter sizing chart to document array kWdc, target DC/AC ratio, module Voc and Vmp, cold-weather string voltage, MPPT window, and inverter follow-up.
Battery Capacity Runtime Chart
Use this battery runtime chart for 12 V x 100 Ah = 1,200 Wh, 80% DoD = 960 Wh, 400 W load = 2.4 h, and module-count checks.
Frequently asked questions
These answers explain how to use the chart without turning a quick reference into a final design decision.