How We Test

By Jake Mercer · Off-Grid Homesteader & Former Engineer

Every number in a review on this site — panel output percentages, filter flow rates, battery cycle counts, batch costs — comes from a measurement taken on this homestead, not from a manufacturer spec sheet. This page explains how those measurements are taken, what equipment is used, and where the limitations are.

My background as a mechanical engineer shapes how I approach product testing. Engineering work requires quantifying performance against a known standard, documenting variables, and being honest about what the data does and doesn’t show. I apply the same approach here. When I can’t measure something precisely, I say so — and I don’t invent a number to fill the gap.

Solar Panel Testing

Solar panels are tested on the south-facing roof array of the main cabin on my 14-acre Tennessee property. Panels are installed at a fixed 30-degree tilt, which is close to optimal for this latitude (approximately 36°N).

Equipment used:

• Fluke 87V True RMS Multimeter — DC voltage and current measurement
• DC clamp meter (Klein CL800) — current draw under load
• Kill-A-Watt EZ for AC load measurement on inverter output
• Renogy BT-1 Bluetooth module — charge controller data logging (solar input watts, battery state)

Testing protocol: Output is measured on clear-sky days between 11am and 1pm local time when irradiance is at or near peak. I measure open-circuit voltage (Voc), short-circuit current (Isc), and actual power output under a representative resistive load. I run at least three measurement sessions across different days and use the average. I compare tested output directly against the panel’s rated STC power to calculate the output deficit percentage.

For comparative reviews (like the budget panel comparison), panels are tested in the same mounting location on the same days where possible to eliminate weather variability as a confounding factor.

Water Filtration Testing

Water filter testing is done in the cabin kitchen using four different source waters: municipal tap (from town supply when visiting), well water from the on-site hand-dug well (moderate mineral hardness, ~180 ppm TDS), collected rainwater from the cabin roof catchment system, and turbid water pre-settled from the lower pond.

Equipment used:

• HM Digital TDS-EZ TDS meter — total dissolved solids (pre- and post-filtration)
• Digital kitchen scale (Escali Primo, 0.1g resolution) — for timed flow rate tests
• Standard 2.25-gallon Big Berkey upper chamber as reference volume for gravity filter flow tests

Flow rate protocol: I measure the time to filter a full upper chamber of each source water type, repeating each test three times after filters have been in use for at least 50 gallons (to allow break-in). Flow rate is reported as gallons per hour (GPH) calculated from the average of the three timed runs. Filters are scrubbed to baseline before any comparative tests.

I do not have laboratory-grade equipment for contaminant removal verification. For filtration performance claims (bacteria removal percentages, etc.), I rely on published independent lab tests and note when I’m citing third-party data rather than my own measurement.

Food Preservation Equipment

Dehydrators, freeze dryers, and pressure canners are tested under working homestead conditions — meaning real garden produce, real batch sizes, and real off-grid power constraints. I’m not simulating off-grid use; this is actual off-grid use.

Equipment used:

• Kill-A-Watt EZ — total kWh consumed per batch
• Fluke 87V — spot current draw measurements at startup and steady state
• Digital probe thermometer (ThermoPro TP-17) — chamber temperature verification
• Kitchen scale — pre- and post-processing weight to calculate moisture removal

What I measure: Energy consumption per batch (kWh), batch throughput (lbs in, lbs out), run time per batch, and real operating cost at our solar-charged battery bank cost basis. For freeze dryers specifically, I track nutrient-retention comparisons against dehydration using published food science data — I don’t perform my own nutritional analysis.

Hand Tools and General Equipment

Hand tools — axes, saws, garden tools — are evaluated over extended daily use, not a single session. A splitting axe gets reviewed after a full cord of wood. A pruning saw gets reviewed after a full season of use. The metrics are durability of the edge, handle comfort over time, and whether the tool performed as claimed under real working conditions.

I note when a tool is new at time of review vs. when it has been in use for a significant period. Short-term reviews are labeled as such.

What I Don’t Test — and Limitations

I’m one person with a working homestead and a set of field-grade instruments, not a laboratory. There are real limits to what I can measure:

• Long-term degradation curves. I can report on equipment performance after 1–3 years of use. I can’t independently verify whether a solar panel’s output will be 80% or 90% of original at year 15.
• Contaminant-specific filtration. I can measure TDS reduction and cite lab testing. I can’t independently verify removal rates for specific pathogens or heavy metals.
• Controlled climate variables. Outdoor testing in Tennessee means variable temperature, humidity, and cloud cover. I control for this as much as possible (same days, same conditions for comparisons) but cannot eliminate it entirely.
• Sample size. I test one unit of each product. Manufacturing variability is real — my unit may perform slightly better or worse than the average production unit. I note batch or production year where known.

If you notice a discrepancy between what I’ve reported and what you’re experiencing with the same product, the contact page is the right place to raise it. Reader feedback — especially from people using equipment in different climates or conditions — genuinely improves the accuracy of future reviews.

Affiliate Links and Independence

Some links on this site are affiliate links. When you buy through those links, I earn a small commission at no additional cost to you. The affiliate relationship does not influence ratings, recommendations, or test methodology. Products are purchased at retail price — I don’t accept review units from manufacturers. The ECO-WORTHY panels that got a 6.5/10 and a “Conditional Buy” verdict still have affiliate links. The score reflects the testing, not the commission.

See the full affiliate disclaimer for more detail.