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Solar Pal sizes a solar power system in three steps. Complete them in order — each step unlocks the next.
AGM (sealed) — maintenance-free, no off-gassing, slightly better cold performance, 60% DoD.
Gel — sealed, vibration-resistant, sensitive to overcharging, 60% DoD.
LiFePO4 lithium — highest cycle life, lightest weight, 80% DoD, but must NOT be charged below 0°C without a BMS low-temperature cutoff.
Enter every device that will draw power from the system. Solar Pal totals them to determine how much energy your system must generate and store each day.
Temperature derating — panels lose efficiency as they heat. Cooler climates (>40°N) −4%; tropics up to −8%.
Dust & soiling −3% — dirt, snow, and debris. Clean panels regularly.
MPPT / charge controller −3% — power conversion losses in the maximum power point tracker.
Battery round-trip −5% — heat losses during charge and discharge cycles.
Inverter — DC-to-AC conversion loss based on your inverter efficiency setting.
The total derate is applied to your daily load to calculate how much the array must actually produce.
Android (Chrome): Open the app URL → tap the ⋮ menu → “Install app” or “Add to Home screen” → Install.
Questions, bug reports, or commercial licensing enquiries:
Solar Pal is a solar power calculator for designing off-grid and grid-tied residential solar systems. It computes panel counts, battery banks, wiring configurations, and system losses using real astronomical solar calculations.
Developed by DEC Group Inc. · decgroup.pro
© 2025 DEC Group Inc. All rights reserved.
The Solar Pal name, DEC Group name, logo, and associated marks are trademarks of DEC Group Inc.
This software is provided free of charge for personal, non-commercial use only under the following terms:
THIS SOFTWARE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. DEC GROUP INC. SHALL NOT BE LIABLE FOR ANY DAMAGES ARISING FROM USE OF THIS SOFTWARE. OUTPUT IS A DESIGN AID ONLY — CONSULT A LICENSED ELECTRICAL ENGINEER FOR ALL REGULATED INSTALLATIONS.
For commercial licensing enquiries: decgroup.pro
Peak sun hours are derived from real astronomical formulas: solar declination by day-of-year, sunrise hour angle from latitude + declination, surface irradiance adjusted for panel tilt and azimuth. System derate applies wiring, temperature, dust, MPPT, battery round-trip, and inverter losses. All project data is stored locally on your device — nothing is transmitted to any server.