Solar 101: from panels to your electricity meter

A rooftop PV system converts sunlight into electricity, supplies household loads when the system can serve them, and may export a surplus under a utility agreement. Understanding the hardware is different from knowing what that electricity will be worth on your bill.

From module to inverter

The U.S. EIA explains that photovoltaic cells convert sunlight into direct-current electricity. Cells form modules, and modules form an array. An inverter converts DC into alternating current for AC loads and a grid connection. Module DC nameplate capacity and inverter AC capacity describe different parts of the system; neither is a promise of continuous output.

kW is power; kWh is energy over time

Power describes the rate of electricity production or use. Energy describes the amount over an interval. A system rated in kW does not produce that full rating all day. Sunlight, orientation, shading, temperature, conversion losses and equipment limits affect production. Compare annual and monthly kWh estimates with their assumptions, not just the module count.

Generation, onsite use and exports are different readings

Electricity used onsite can reduce grid imports. Surplus may flow through the utility meter as an export; at other times the home still imports electricity. An inverter's production total is not automatically the same as exported energy or bill savings. Your tariff determines how imports and exports are valued.

Solar panels alone are not a backup promise

Do not assume the home will remain powered in an outage. Ask which equipment can isolate the home safely from the grid, which circuits are backed up, and whether the proposed system can operate and recharge during an outage. DOE discusses storage and microgrids as part of resilience; the presence of panels alone does not establish a particular home's backup capability.

Production models have limits

The DOE national-laboratory PVWatts tool explicitly cautions that its predictions contain assumptions and uncertainties. It exposes inputs such as DC size, tilt, azimuth and losses. Ask the installer for those settings and a site assessment. A weather-based model is not a structural inspection or a guaranteed output contract.

Use the sun tool for context and the net-metering guide to understand why production and savings are separate questions.

Before you decide

• Request a labeled system diagram with DC capacity, inverter capacity, meter and any storage.
• Ask for monthly and annual production estimates with shading, orientation and loss assumptions.
• Confirm which loads operate in an outage and any equipment or reserve settings required.
• Check the tariff and written permission-to-operate requirements before assuming exports earn credits.
• Keep monitoring, warranty and service contacts; compare measured production with the modeled season.

Sources and review limits

• U.S. EIA Photovoltaics and electricity — updated May 24, 2024; used for PV/DC/AC concepts, not as a 2026 market-price or tariff dataset.
• DOE national-laboratory PVWatts calculator — input fields and performance cautions reviewed; model estimates are not site surveys or production guarantees.
• U.S. Department of Energy Solar Energy — general technology and storage/microgrid context, not an engineering design or local tariff.

Source review: 2026-09-24. This is our access/review date, not the publication date of every source. Source concepts support this explanation, not a site-specific engineering plan or output guarantee. Checklists are editorial buying questions, not individual tax or engineering advice.