Home Solar Energy Solutions: An Introduction

Solar energy has become very popular in recent years. It’s an environmentally friendly option, producing energy without releasing greenhouse gases into the atmosphere. It allows for energy independence, producing energy on your own without connecting to the grid and being subject to the price shocks that come with that. And as prices continue to fall, a solar power system becomes a more attractive investment, paying for itself in increasingly smaller time frames.

In a solar power system (also known as a photovoltaic system), power is produced for your home using a 3-part system. Solar panels, usually placed on your roof and facing south in the northern hemisphere, absorb sunlight and convert it into direct current. Mounting systems adjust the angle of your solar panels, to optimize energy absorption. Then an inverter converts the power from direct current to alternating current, making it usable for household appliances.

TYPES OF SYSTEMS

There are two options for the surplus energy produced- a grid connect system, and a standalone system.

A grid connect system works like this- during the day, solar panels produce electricity, supplying all of your energy needs. All surplus energy is fed back into the grid, for which your energy provider pays you. This is commonly known as a Feed in Tariff. During the evening, the grid supplies your household’s energy needs. In this manner households can greatly reduce their energy bills, sometimes even turning a profit when the energy they feed to the grid exceeds the energy they take from it.

A standalone system is designed to be independent of the gird. The surplus electricity generated during the day is fed into storage batteries. The system should be designed so that enough energy is collected during the day to supply the energy needed for the evening. A backup generator is an extremely good idea for such a system, to supply power in periods of very high demand or extended cloudy weather/winter months. Where overall performance is the focus of a grid connect system, in a standalone system daily energy generation to meet your needs is critical.

Check out this article if you’re interested in solar water heaters for your home.

EQUIPMENT DETAILS

Solar Panels

The solar panels (or solar module) are where the energy is produced. The panels are made of silicon, and when they absorb the light from the sun they give off electrons. These electrons are then harnessed and turned into the kind of electricity used in the home.

There are 4 kinds of solar panels available commercially.

Single crystal modules have been around the longest and are the most effective. They are the most efficient (10-17%) but also the most expensive. They are the dotted or octagon shaped panels you would often see on satellites.

Poly/Multicrystalline modules are second in line. They are cheaper than single crystal, but run at 9-14% efficiency. They are the blue colored panels you sometimes see.

String ribbon modules are fairly cheap and are 7-8% efficient.

Thin Film (Amorphous) modules are a thin layer of silicon deposited on top of steel or glass. They are cheap to make, but their efficiency is very low (5-7%). This is what they use in solar powered calculators.

Solar modules are rated by wattage output, more accurately peak watts (STC). These are based on laboratory conditions, and real life results will tend to fall short of these. Plan for an output of 80-90% of the STC.

While summer has longer days and therefore more hours of direct sunlight, PV systems perform more efficiently at lower temperatures. A clear winter day with sun reflecting off of the snow may potentially produce more energy output than a hot summer day.

The best situation is to have your panels face south (In the northern Hemisphere). They can face East/West, but that will lose 10-20% efficiency. Facing north is basically useless.

Mounting System

These adjust the angle of your panels to optimize energy production. You’ll generally want the angle of your panels to be equal the distance you are from the equator is degrees of latitude. For example, New York City is at 40 degrees latitude, so you’d want your panels to face south at a 40 degree angle in NYC.

Inverter

Amplifies one voltage to another, and converts direct current to alternating current, which our homes use. 6-13% of energy is lost. The cooler it is, the more efficiently it operates, so a fan or a heat sink a good idea.

COSTS

A PV system tends to cost a lot up front, and pay for itself over the years. Costs are always changing, and there are a ton of factors involved- how much direct sunlight you receive, the cost of the system, the efficiency of the system, how much energy your household uses, installation costs, etc. It would be silly to give any specific figures, but as a general range systems tend to cost in the $7500-$25,000+ range depending on various factors. An average household would probably be looking at just over $10,000 for having a system installed, as of the time of this writing.

Off-grid systems tend to cost significantly more, because they’re required to produce more power, and have battery systems/back up generators that must be included as well.

There are various incentive programs to make solar energy cheaper. In the US there is a federal tax credit that will rebate 30% of your overall system and installation costs. There are also various programs at the state level (check out this site to see what your state offers: DSIRE: DSIRE Home).

All in all, in most cases it will take 10-20 years for the solar panels to pay for themselves. But considering some are guaranteed for 30+ years, it’s not a bad investment at all.

Good luck and stay prepared!

Thanks to RamboMoe for his contribution. You can read more from RamboMoe at his site, preparedforthat.com