Rising utility costs and growing environmental concerns have made household energy efficiency more important than ever. You’ve replaced all your incandescent light bulbs with CFLs or LEDs, sealed every last gap and crack around your doors and windows, and replaced all your outdated appliances with modern, energy efficient models. But what else can be done to decrease your home’s energy usage? One increasingly practical option is to harness the power of the sun. Home solar power has seen a surge in popularity in recent years with good reason; a properly sized and installed system can substantially decrease or even eliminate your electric bill, saving money in the long run and decreasing your home’s carbon footprint. There are two main types of solar energy systems for home use: photovoltaic (PV) systems, which use silicon semiconductor cells to generate electricity from sunlight, and solar hot water systems, which concentrate sunlight in order to heat water for use in your home.
Photovoltaic systems are centered around an array of panels, typically installed on a rooftop and angled toward the south to maximize sun exposure. They work by capturing photons from the sun and generating an electrical potential through the photovoltaic effect. These systems produce DC, or direct current, so they require an inverter to produce AC power to be used within the home. Modern PV systems require no bulky and inefficient batteries, and can be connected directly to the grid using a special meter which will be installed by a qualified professional. These systems produce lots of energy during the daytime, often outpacing the home’s electricity usage. In this event, the meter runs backward, subtracting kWh off your bill. In this way, a PV system can be beneficial even if most of your energy usage is at off-peak hours. Due to their complexity, they must be professionally installed.
Once prohibitively expensive for anything other than niche applications, PV systems have seen a dramatic drop in price in the last 10 years, now coming in at less than $5 per watt installed. What does this mean for the average homeowner? Home energy needs vary greatly from house to house based on size, number of occupants, and other factors such as climate. Solar PV systems will typically range in cost from about $10,000 to $50,000 installed and generate between 500-5000 kWh per month. The lower end of this range will make a sizeable dent in the energy needs of the average home, while higher end PV systems will accommodate the full electrical needs of all but the largest homes. There is a 30% federal tax credit on all PV systems including installation, with no maximum payout. This means that the homeowner’s out of pocket cost is effectively 30% less than the quoted price. In addition, many states offer individual tax credits based on system output or cost, and many utility companies will subsidize the cost of installation. Combined, these credits mean a homeowner could pay for as little as half of the total system cost. Since solar PV systems are still a substantial investment, many solar contractors offer payment plans, meaning a properly sized and funded system could start saving money immediately, with no out-of-pocket cost.
If you would like to make the leap to home solar, but a photovoltaic system is too large of an investment, a solar hot water system might be a better option. These systems can generate hot water not only for use at the tap, but can also heat the whole house using radiant floor heating or hot water radiators. Since home heating and hot water account for 75% of the energy usage of a typical home, this can result in substantial energy savings. Solar water heaters, at their most basic, consist of a solar collector through which water flows, and a tank to hold the resulting hot water. Simple systems have a roof mounted tank and use a thermosiphon effect to circulate the water through the collector. More complex systems use a pump to circulate the water, allowing the tank to be located inside the building for aesthetic reasons. Some systems also circulate an antifreeze solution through the collector, which then transfers heat to the hot water reservoir. This type of system, known as a closed-loop system, minimizes maintenance on the collector by reducing mineral buildup from hard water and also eliminates concerns about freezing in cold climates. Either type of system can be supplemented by a normal gas or electric water heater, ensuring that hot water is always available, even in times of high hot water demand.
The main advantage of a solar hot water system over a photovoltaic system is the price. A basic system can be had for as low as $2,000, which will provide most of the hot water needs of a small family. A more complex system might cost around $10,000 and would be more than sufficient to heat and provide hot water for a typical home, depending on size and climate. As with PV systems, a 30% federal tax credit applies, and many states offer additional tax rebates, so the effective cost to the homeowner is substantially less than the retail price. A solar hot water system offers superior bang for your buck compared to a PV system.
If you’re looking to decrease your home’s energy consumption with solar power, photovoltaic and solar hot water systems can both achieve that goal. The difference comes down to individual preference, desired investment, and characteristics of your home and climate. PV systems can generate electricity for a variety of uses throughout the home, but they come at a premium price. Solar hot water systems tend to have a lower initial cost than PV systems, but they are useful only for space heating and hot water, which account for the majority of a typical home’s energy usage. Either system, when properly used, can increase home energy efficiency and help prepare your home for a greener future.