Basics of Electricity in Solar Technology

• Electrical Power measured in Watts
• Electrical Potential measured in Volts
• Electrical Current measured in Amps

You'll note that a retail provider of solar system components, Renogy.com says this in their overview of their Inverters.  Renogy is by no means the only provider of sola power system components but they are reliable, they provide quality components, and they have excellent consumer support.

The basic electrical circuit is described in the vCalc collection on Circuits.

Combinations of Voltage and Amperage

We saw in the equation above that power is the product of voltage and amperage.  But there are two ways to combine the power coming from multiple solar panels and we illustrate it here using two of the example high efficiency solar panels discussed above.  Typically a solar power system will contain a number of solar panels interconnected but we will illustrate the two ways to combine voltage and amperage with an example using only two solar panels.

Remember, our solar panels are a contained panel with a positive and a negative output connection.  We don't have to deal with anything internal to the solar panel.  We are only concerned with how the positive and negative connections on one solar panel connect to the positive and negative connectors on other solar panels.

The example high efficiency solar panel has specifications:

• nominal max power = 325 Watts
• max power voltage = 57.6 Volts
• max power current = 5.65 Amps

So, depending on how we wire the solar panels, we can get  either a current of 11.3 Amps or 5.65 Amps from the combination of two of the example high efficiency solar panels.  We can also produce our choice of 57.6 Volts or 115.2 Volts. The choice of voltage and amperage directly output from the two solar panels is a matter of how you wire the two together.

To increase current (amperage) we wire sets of solar panels in parallel with plus to plus and minus to minus. To increase total output voltage, we wire sets of solar panels in series.  Series circuits connect minus to plus.  In either case, the formula of equation 1 (EQ1), shows the total output power is the same whether the example solar panels are wired in parallel or series.

Notice that on the far right of the picture above labelled Two 325 Watt High Efficiency Solar Panels Combined, the circuit has a positive and negative lead extending from the right side of the picture.  There would be power between these two leads and they should not touch each other in the real-world implementation.  If the red positive and black negative connectors come in contact, that completes the circuit and in the simple example shown that would "short-circuit the power and possibly damage the solar panels.  We discuss ways to avoid damaging the solar power system's components and to avoid dangers of the electrical system as a whole in the vCalc Collection: Solar Panel Safety.

Range of Power for Photovoltaic Solar Panels

Solar Panels are composed of many cells.  Length and width of solar panels varies but most manufacturers are producing solar panels in standard sizes. The most typical sizes used are

A car battery generates energy as DC. We generally have the goal to produce alternating current (AC) electricity that is compatible with the 120 Volt standard of contemporary households in the US.

The electric generator producing the simplest AC current, a current in a circuit with a simple resistive load, has both sinusoidal current and sinusoidal voltage.  That is, the current and voltage both rise and fall in a sinusoidal pattern. If the circuit is purely resistive, then the voltage and current reverse polarities at the same points in time on the sinusoidal curve and the product of voltage and current is always positive.