Day 52: Renewable Energy III—Solar Power

Dear Student,

If you’re lucky enough to live in a climate that gets plenty of sunshine, you can easily become self-sufficient in power using a solar system…

The obvious drawback of solar power is that it can only be produced when there is direct sunlight. In more northerly or southerly parts of the world, your daylight hours reduce significantly during the winter months.

If you live or are planning to live in a remote area, the cost of getting power to your homestead might be prohibitive or impossible to achieve… Being power independent allows you to live wherever you choose and perhaps enable you to buy significantly underpriced property due to the cost of getting utilities to it.

Being fully self-sufficient in power can save you tens or hundreds of thousands of dollars on the cost of getting utilities to your property.

You can buy your own off the shelf “plug-and-play” solar system or get a qualified solar contractor to assist you.

A Solar Power System

A photovoltaic (PV) system

produces a direct current (DC) using a silicone semiconductor that interacts with sunlight to produce power.

An inverter converts this power to alternating current (AC) for use in modern appliances.

It is possible to run your home more economically off a simple 12-volt system, but you would have to get 12-volt appliances, like those supplied for boats and motorhomes.

Parts of a PV system

• Solar Array: collection of connected solar cells
• Charge controller
• Inverter
• Storage device (batteries)
• System meter
• AC breaker box for the house
• Backup generator

Storage

Solar systems obviously only capture energy during the day, but as power demands vary throughout the day and night, you need a storage device to allow uninterrupted power usage.

You should store enough power for three days of power in case of low sunlight (cloudy days) during which power generation would be sub optimal.

Batteries

Lead acid or wet-cell batteries are old technology and therefore inexpensive, but they require some maintenance. Topping off the batteries with distilled water and sometimes battery acid is necessary every couple of months. These batteries also produce small amounts of flammable hydrogen gas, so their storage area must be well ventilated.

AGM (absorbent glass mat) or gel cell batteries require no maintenance and are resistant to freezing, but they cost more to buy and some have shorter life spans than lead acid.

Tesla lithium ion battery banks are perhaps the newest entrant to the home power storage industry (Tesla’s power wall). This smart charging battery system can store ample energy for one home, and batteries can be linked together to allow larger storage capacities.

If you have cheaper nighttime power rates than during the day, you could store cheaper night power and use it during the day as a cost saving measure to save money to pay for your future solar system.

As batteries can cost up to third of the cost of your system, you should size your system to fulfill your needs. Take an energy audit of your current needs and don’t overengineer your system’s capacity unless you are sure you will require more power in the next several years.

All batteries must be replaced at the end of their useable life. The cost of replacing the batteries should be budgeted for and written off over 7 to 10 years to ensure you have the funds to replace the batteries at the end of their life cycle. With this in mind you should save at least 3% to 4% of the cost of your system in liquid assets every year to allow for future battery replacement. This allocation does not cover monthly or annual maintenance costs of the rest of the system if you pay someone to do it for you.

Backup generators are useful for when you have inclement weather or additional power requirements.

Solar concentrating mirrors use parabolic troughs to power steam engines to produce electricity. The heat of the sun is concentrated to such a degree that it melts salt and can store the heat for days. This can obviate the need for batteries during cloudy days.

Orientation

In the Northern Hemisphere, your solar array should be south facing and tilted to the angle equal to your latitude.

Due to the high price of older solar panels, early systems recommended expensive solar trackers that turned to follow the sun for maximum exposure throughout the day.

Today, solar panels are inexpensive and putting some extra panels on the southeast and southwest sides of your home should easily compensate for any lost power an expensive motor-powered solar tracker would add.

DIY Solar Panels

If you want to try build as much of your power system as you can yourself to save money, you can purchase kits that allow you to assemble your own solar panels at home. Newer versions available online allow for power outputs similar to most factory assembled panels and can reduce the cost of your system. That said, the price of good-quality panels has reduced to the point it doesn’t make much financial sense unless you have a lot of spare time.

DIY solar panels require more skill, but large, low-power panels can be built the old-fashioned way if you want to go the extra mile. Various methods of using copper sheets and salt water or conductive glass and titanium dioxide can be found online and might be of use in an emergency situation, but they aren’t practical in larger scale operation.

Grid Tying

If you live on the power grid or are close enough to connect to it, you could install a grid-tied (connected) system.

Your system could supply your power needs and you can top up your requirements from the grid when needed, which eliminates the need for a backup generator (and its significant cost). If your local power company has a system that buys back power from renewable producers, you could even make a profit selling excess power back to the grid.

This also eliminates the need for batteries, but the obvious drawback from having no batteries is that you will have no storage capacity in the event of a power failure during the night.

Buying A Ready-To-Go System

Google solar power systems and research reliable manufacturers (consider consumer reviews).

The housing of the batteries and other equipment doesn’t require a large amount of space. A small closet or broom cupboard is sufficient in most situations, so long as it is well ventilated (especially if you have wet acid batteries).

Installing your own off-the-shelf system can save money, but unless you are relatively handy with electricity, I recommend hiring a professional. Good-quality systems should last you decades, so why risk damage by incorrectly installing it yourself?