Going solar at home: The basics
Installing solar panels can decrease your household’s carbon footprint to such a degree, that you’d have to plant 88 trees every year to offset that amount of carbon dioxide!
01 October 2018 | Energy
So, why use solar panels? Simply, to reduce your carbon footprint and save an average of N$700 per month (depending on what your current use is) on your electricity bill.
Solar panels are photovoltaic (PV) cells. In a nutshell, these special batteries harness sunlight, transform it into energy, then send that energy to an inverter, which converts it into electricity to power the home.
Because installing solar panels isn’t as simple as slapping cells on a rooftop, you’ll need to install additional wiring, and panel placement is key to building an efficient system. So this is one that’s best left for the pros. Look for a solar pro who:
• Offers a good warranty. Be sure the inverter is covered for at least 10 years and the panels are covered for 20 to 25 years.
• Uses panels made by a manufacturer with a proven track record.
• Doesn’t outsource installation. There will be more accountability if things don’t go according to plan.
• Can supply at least two recent customer references.
How it works
Photovoltaic cells absorb sunlight during the day to charge the batteries, which then light the bulb at night. Because solar lights are powered by the sun, they must be placed in an area that receives full sun — ideally eight or more hours per day.
It seems obvious, but your roof needs to receive direct sun during the time of day when the sunlight is strongest (usually between 10:00 and 15:00) for your system to work efficiently. Trees, tall buildings, and even a chimney can all affect your panels’ sun exposure. Also remember that different kinds of panels react in various ways to shadow. But, the more hours your panels are exposed to full sun, the more efficiently they’ll generate power. The amount of solar radiation that reaches the ground during a given period of time also differs depending on the region you live in.
The size of a system depends on two things: insolation and how much energy is needed. To get an idea, look at your electric account to find out how many kilowatts of energy you use on an average day. Multiply that by .25, and that’s about how big a system you’ll need.
As for how many actual panels you’ll require, that will depend not only on output per panel, but also on insolation and how many hours per day the panels will receive peak sunlight. Sound complicated? That’s because it is. That’s why we recommend that you hire a reputable pro.
It takes all kinds
Different panel types do different things. But before we get into a more advanced look at specific technologies for heating water and providing electricity to a home with solar energy, it’s necessary to understand the basics of what kinds of panels are out there. Some of them aren’t really panels at all, in fact, but rather tapes or films. Let’s clear things up.
Solar energy can do two things for your home:
• It can provide power, in the form of solar energy converted to electricity, or
• It can heat water, through direct or indirect solar radiation.
Panels that provide electrical power are photovoltaic (PV for short). Panels that heat water are often described as solar thermal collectors.
It gets confusing because we sometimes shorten “solar thermal collectors or panels” to “solar panels” in conversation, and that is easily mixed up and used interchangeably (even by professionals) with “PV panels”.
However, it’s important to understand that the work the solar energy does in both kinds of panels is different. In the first it provides electricity. In the second it heats up water.
Choices, choices, choices
Using solar lighting outdoors can be a lifesaver when outdoor outlets are not available. But do solar-powered lights really work? How do they measure up to hardwired electric lights? And what if your yard is shady or you live somewhere that rarely sees the sun?
If you are putting solar lights in your desert yard, they are sure to operate at maximum strength, but what if you have a heavily shaded yard? It’s not quite as simple, but you can still have solar-powered lights, even in a fully shaded area. A solar or landscape lighting pro can help position a remote photovoltaic panel on your roof or in a sunnier area of your yard, which can then be wired to the lights in the shady area.
If there simply isn’t much sunlight to be gathered, even on the roof, the solar lights will still work, but they won’t shine as brightly or for as long each evening.
• Solar path lights are small solar lights on stakes, which can be pushed into the ground alongside a walkway to softly illuminate the path at night. They are not as bright as electric path lights, so plan to use more (up to twice as many) to light your path with roughly the same glow as electric. These small lights are ideal for illuminating walkways far from exterior outlets, and can provide an enchanting glow along winding garden paths.
• Ambient and decorative solar lights include colourful blown glass, decorative lanterns and string lights, however they are not as bright as solar path lights. Used in multiples or alongside path lights and spotlights, they can provide a warm ambient glow. Place a few glass solar lights on stakes in your garden beds for soft landscape lighting, or hang solar string lights over an outdoor dining table for a welcoming touch at your next gathering.
• The brightest solar lights available are called task lights or spotlights, and the best ones can provide light that’s roughly equivalent to a 40-watt incandescent bulb. That is still not as bright as a typical outdoor spotlight, so you may want to double or triple up in areas where you want bright, direct light. Motion-sensing solar spotlights can be used near doors and in the driveway. Spotlights can also be placed in the garden, with the beam of light directed at a tree or another landscape feature.
• Since most solar-powered lights today use LED bulbs, the light they emit is bright white. If you want the look of incandescent bulbs, look for solar lights with tinted covers — they may be labelled “amber” or “soft white.”
• The brightness of a solar light depends on the brightness of the sun and the amount of daylight it is exposed to, but it also depends on the quality of the photovoltaic cells and the size of the LED bulb. Higher-quality photovoltaic cells and larger LED bulbs tend to cost more, so to a certain extent, the higher-priced solar lights do tend to shine more brightly.