Lookup data
Reference tables for small DC solar systems
These pages exist so you do not have to take a number on faith. Each table states the document it came from, the assumptions baked into it, and the conditions under which it stops being valid. Where published sources disagree, we show both values and say why.
DC Wire Ampacity Tables for Copper Conductors (NEC vs ABYC)
Two different standards give two different answers for the same wire. This page shows both, explains why they disagree, and walks through applying the derating factors that turn a table value into a number you can actually design around.
DC Voltage Drop Tables and Formula for 12 V, 24 V, and 48 V Systems
Voltage drop, not ampacity, is what usually forces you into bigger wire on a low-voltage system. These tables give the longest run each conductor supports before the drop exceeds your budget, and the formula so you can compute any case they do not cover.
AWG to mm² Conversion Table for Solar and DC Wiring
American gauge numbers and metric cross-sections do not line up neatly, and the nearest metric size is often smaller than the AWG size it is sold as replacing. This table gives the exact figures plus the buying traps that make a cable perform worse than its label suggests.
DC Fuse and Breaker Sizing for Small Solar Systems
Overcurrent protection is the part of a small solar system that does nothing at all until the day it is the only thing standing between a short circuit and a fire. This page covers the sizing rules, where each device belongs, and the interrupting-rating question that catches almost every lithium build.
LiFePO4 vs AGM vs Gel vs Flooded: Off-Grid Battery Specification Comparison
Nameplate amp-hours are the least useful number on a battery label. This page compares the four common chemistries on the specifications that actually decide system cost and size, with every figure traced to a manufacturer datasheet and the gaps in the published data named rather than filled in.
Battery Temperature Limits: Charge and Discharge Ranges by Chemistry
Charge and discharge temperature limits are not one number per chemistry — they vary by manufacturer, and lead-acid doesn't work on a cutoff at all. This page is the lookup table: charge cutoffs with their source, discharge ranges, the lead-acid freezing-point-by-state-of-charge table, and temperature-compensation coefficients, with anything we couldn't verify labeled as such rather than filled in.
PV System Loss Factors: Where the Nameplate Watts Actually Go
A PV module's nameplate wattage is a laboratory number. This page walks through the ten loss factors that separate that number from real-world output, shows why they combine multiplicatively rather than additively, and flags which losses are within a builder's control and which are not.
Peak Sun Hours: What the Number Means and How to Get Yours
Peak sun hours is not a weather statistic — it is a unit conversion. This page defines it precisely, explains why a single city-average number is close to useless without your tilt and azimuth, and walks through generating your own figures instead of trusting a table.
PV Temperature Coefficients and Cold-Weather Voc
A PV module's open-circuit voltage rises in the cold and its power output falls in the heat, and both are governed by the same temperature coefficients. This page gives verified coefficients from three datasheets, the formula for cold-weather Voc, and the NEC 690.7 rule that exists because of it.