Lesson 6 – O: Orient Your Learning: How Do We Build and Use Photovoltaic Panels?

O: Orient Your Learning

What You Already Know, Scaled Up to a Full Panel

You already know that a solar cell produces voltage and current, and that power can be calculated using:

P = V x I

A photovoltaic panel is built by connecting many solar cells together. The way the cells are connected changes the panel’s electrical output.

Series and Parallel Connections

In a series connection, the voltages of the cells add together. The current stays about the same.

Diagram showing two solar cells connected in series. The positive output connects to the positive terminal of the first solar cell, the negative terminal of the first cell connects to the positive terminal of the second cell, and the negative terminal of the second cell provides the negative output. A note explains that in a series connection, voltages add together while current stays the same.

In a parallel connection, the currents of the cells add together. The voltage stays about the same.

Diagram showing two solar cells connected in parallel. Both positive terminals are connected by a red positive bus, and both negative terminals are connected by a black negative bus. Callout boxes explain that the positive terminals are connected together and the negative terminals are connected together. A summary notes that in a parallel connection, voltage remains the same as one cell while current (amps) adds together.

This means engineers can design panels to produce the kind of electrical output a system needs.

Example

Suppose one solar cell produces 0.5 volts and 0.2 amps. If you connect two cells together, their output varies based on if they are connected in a series or in parallel.

In both cases, power changes because power depends on both voltage and current.

Panel Specifications

When engineers compare panels, they often look at:

Rated power: how much power the panel can produce under standard conditions (STC)
Voltage: how much electrical push the panel provides
Current: how much charge the panel can deliver
Module Efficiency: how much sunlight becomes electricity per unit area
Temperature coefficient: how much panel output changes when the panel gets hotter

Reading the panels allows engineers to select the best panels for the job.

Think About It

Why might temperature matter when choosing a panel for a hot location?