Solar 101: The Basics

solar power systems generally have only 4 major parts

Solar power systems aren't that complicated

The short explanation is that:

1. Modules make the electric power (DC Power)

2. Inverters change the DC power to something that your building can use (Typically DC-->AC)

3. Batteries are optional, but put the cherry on top by storing any excess power, for night-time, hazy days, or emergency power (Batteries are DC only)

4. Racks are not optional, and they keep your panels securely anchored to the ground or your roof so they don't blow away in the wind

Photo Voltaic Modules

(aka solar panels)

Hooking up solar panels is simple. They all use a common plug type, and just daisy chain together. They all come with a positive lead, and a negative lead, and like a battery, you hook them up either in series and/or parallel until you reach the voltage and amperage that your inverter is designed to handle. If it's for a whole home system, the exact volts and amps don't matter too much so long as you get the appropriate wattage that you need without maxing out either the voltage or amperage ratings in your system which would fry your equipment.

Most PV modules use thin slices of semi-conducting silicon (normally called wafers) to produce electricity when exposed to sunlight. When two of these wafers are layered together they form a solar cell with a voltage gradient between the two layers. Like a cell in a battery pack, the solar cell is the basic building block of a solar panel.

Specifically how these cells work is that: one layer of silicon is alloyed with an element that gives it excess electric charge (thus it becomes negatively charged, or n-type, usually phosphorus) and the other is alloyed with an element that makes it deficient and readily take on electric charge (thus positively charged, or p-type, usually boron). The electrons in the n-type wafer are only very loosely attached in their crystal lattice, and the energy carried by the photons in sunlight is strong enough to break these electrons free and have them zoom over to the other side.

These solar cells are strung together in rows and soldered together in series and then parallel to bring them up to the appropriate voltage and amperage ratings. They are then captured between two layers of clear polymer encapsulant material to protect the delicate silicon wafers from ambient moisture, debris. A sturdy glass top caps the outward facing layer and a plastic backing sheet shields the backside of the panel. All these layers of material are typically put into an aluminum frame and this assembly is what makes up a solar panel.

Roughly there are two common types of silicon cell used for solar panels:

• polycrystalline cells

• monocrystalline cells

Polycrystalline cells are the older less precise technology. They are typically blue-black in color with a crackled surface appearance like broken glass.

Monocrystalline cells are the newer technology that are more difficult to produce and are typically all black and smooth in appearance.

Usually monocrystaline cells are higher quality, but for cheapy marketplace panels that you stick in the garden that don't come with a warranty, the extra performance isn't usually worth the dollar to watt mark-up on these units, especially when these things tend to come under specifications anyway. Modern Rooftop solar panels tend to use exclusively monocrystalline cells.

Solar Panels are properly called photovoltaic (PV) modules:

• Photos = light

• volt = electric potential (named after Alessandro Volta, inventor of the electric pile)

• module = a bundle

Silicon based solar panels nowadays are a commodity good, made in bulk to similar specifications. Chances are, if it is a name-brand panel that comes from a company that's been around a while and has a good warranty, it will be in the same ballpark of quality as the others, and most units are roughly interchangeable, with some exceptions. A typical rooftop grade solar panel will be roughly 1 meter x 2 meters in size, and be around 20-25 kilograms. These are internationally traded goods, thus the metric specifications. In English units, they are roughly 3x6 ft each and about 50-ish lbs typically. Though every manufacturer has different lines of panels and some are slightly larger or more compact than others.

Some "made in the USA" panel brands are:

• JinkoSolar USA (Florida, USA) [JinkoSolar, China]

• Silfab (Canada)

• QCell (South Korea)

Big Chinese import brands here in the USA are:

• JinkoSolar (China)

• Trina (China)

• Canadian Solar (China, formerly Canada)

• Longi Solar (China)

• JA Solar (China)

Some Home Grown USA Solar Panel Brands:

• First Solar (Alabama, USA)

• Mission Solar (Texas, USA) [OCI, South Korea]

• Solar 4 America (California, USA)

• SunPower/Maxeon (California, USA)

• Certain-Teed (Pennsylvania, USA) [St. Goban, Paris France]

Big Non Chinese Import Solar Panel Brands:

• REC (Norway)

• Hyundai (South Korea)

Racking

Racking refers to how your PV modules are anchored in place so they don't fly away in high wind.

The first decision to make is whether you want your system to be set up on the roof of your building or whether you want it mounted on the ground.

If getting the system installed by a professional, attaching the system to your roof is generally the superior option.

Mounting the PV panels on your roof puts the panels in on an area not used for walking or storage. It's basically free real estate!

Each panel is generally 1x2 meters large (~3 ft x 6ft). A typical size for these systems in my area (Miami-Dade County, FL) is generally 16-24 panels (when using ~400w panels), with 20 panels being the average. Thus the area used up by each size system is as follows:

12 panels (4.8 Kw) = 06 panels x 2 rows = 12 ft wide x 18 ft long

16 panels (6.4 Kw) = 08 panels x 2 rows = 12 ft wide x 24 ft long

20 panels (8.0 Kw) = 10 panels, x 2 rows = 12 ft wide x 30 ft long

24 panels (9.6 Kw) = 12 panels, x 2 rows = 12 ft wide x 36 ft long

28 panels (11.2 Kw) = 12 panels x 2 rows = 12 ft wide x 42 ft long

In my area 30 panels systems are about the absolute maximum practical size (12kwDC/~10KwAC) you can hook up to the local utility giant's grid (FPL = Florida Power & Light) without having to pay for the extra insurance that they generally require you to have, if you want to connect a larger residential system to their network.

Watch this space for future info on commercial installations

At that point, the added monthly/yearly insurance premium eats into the margin of your savings by going solar, so at this point it's generally better to make the one time payment of upgrading your home's energy efficiency by swapping out appliances for more efficient ones, or adding insulation and heat rejecting exterior treatments.

Space for link to energy efficiency guide

Space for link to energy efficient appliances

Space for link to heat rejecting exteriors

Both options require generally require the same about of red tape, paperwork, inspection, and permitting. Only the exact permissions are slightly different.

If going to interconnect with the grid, both options require electrical work permits, and must comply with the NEC (National Electric Code).

Installing on your roof requires:

1. roof mount racking system

2. roof inspection

3. roofing permits

Installing on the ground requires:

1. ground mount racking system

2. laying a foundation

3. getting your utility lines marked

4. permit for accessory permanent structures