Solar Power on a Budget

For years, generating one's own electrical power has been a quest for many people. People who are tired of paying high prices for electrical power, ones who want to live out in the 'boonies' away from utility lines, and those who want less polluting and more renewable sources of power have experimented with solar panels as a means of generating clean and renewable power. Until recently, solar power has been cost-prohibitive for most people. While presently it is still too expensive for powering the average American home, many people have put solar electric systems in place for supplemental or emergency power. In this series of articles, some practical real-world solar power systems that the average person can install and use will be discussed.

Photovoltaic, or solar electric panels, are ideal for weekend cabins, recreational vehicles, emergency radio/communications equipment, and battery charging. Amateur, or "Ham" radio operators, use them for running portable radio equipment in the field. Small, reasonably priced 'solar battery savers' are available to keep the batteries in boats and recreational vehicles charged and 'ready to go' at any time. Solar panels no larger than a paperback novel are sold as 'Solar Ni-Cad chargers' for charging Ni-Cad flashlight batteries. Prior to Y2K, many people, including this author, bought solar panels and rechargeable batteries of various descriptions to power shortwave radio gear, run low voltage lighting, recharge flashlights, keep alarm systems operating without line power, as well as run a host of other small appliances. While the 'Y2K scare' is past history, many of us live in earthquake or storm-prone areas where mains power may be cut off for several days to a couple of weeks. Whatever your motivation for considering solar power, technology has produced many new and reasonably priced products to meet almost any need.

Personal backup system consisting of emergency radio, 2 flashlights, alarm, light, TV, CD player. This system is ideal for a small RV/camper/van for weekend outings or for short-term home power outages.

In this case, a shortwave radio and a small battery-operated TV for receiving news, weather forecasts, emergency info, or entertainment. The flashlights are 'two-cell' units which ran off "D" and "AA" pen light cells, respectively. The light is a 30-watt florescent fixture designed to run from a 12-volt car battery. These are commonly sold in auto parts stores and RV supplies dealers. The alarm was homemade, and is used to protect the windows and doors in the owner's trailer. The CD player is a personal 'discman' type unit that uses two AA pen light cells.

Because the TV, the shortwave radio, and the 30-watt light all run off 12-volts DC, it was decided to use a 12-volt Gel-Cell type battery to power these items. The gel-battery offers the advantages of being compact and spill-proof, unlike a car battery which is big and contains sulphuric acid that can leak or spill.

In order to determine how much battery and solar panel power capacity to buy, one must first calculate how many watt-hours of electricity are needed during an average day's use. For this example, let's assume the following:

Shortwave radio - 5 hours of use daily, using 1.2 watts of electricity.
1.2 watts X 5 hours = 6 watt-hours

20-watt florescent lamp - 5 hours daily, using 20 watts of electricity.
20 watts X 5 hours = 100 watt-hours

12-Volt TV - 3 hours of use daily, using 1.2 watts of electricity.
1.2 watts X 3 hours = 3.6 watt-hours

6 Flashlight cells - need charging once or twice weekly, but present a peak load of .3 watts per pair - or .90 watts if all 6 are charged at once.

118.6 watt-hours is the total daily power consumption of all these devices when used for the specified amounts of time.

For greater flexibility and efficiency, it was decided to use individual 'solar Ni-Cad chargers' to handle the three pairs of flashlight cells. Thus the 12-volt gel battery and solar panel were not required to absorb this load, and the 118.6 watt-hours were cut to 109.6 watt-hours.

* Note that it will require 2 - 3 days to charge the flashlight cells, as there are not enough hours in an average day to charge them fully at their ideal charge rate. It is therefore a good idea to keep at least two sets of flashlight cells per device so that they can be rotated.