Solar Energy

Frequently Asked Questions – Solar Energy

Q: Do solar systems produce hot water in the winter?

SPP solar systems will operate and produce hot water during the winter months but may require anti-freeze protection where applicable.

Q: Can a solar water heating system be used in place of a traditional gas or electric heating system?

In order to ensure proper efficiency of your water heating system, a solar energy system must be used in conjunction with a traditional gas or electric heating system, rather than as an alternative to a traditional system.

Q: What is photovoltaics (solar electricity), or “PV”?

What do we mean by photovoltaics? The word itself helps to explain how photovoltaic (PV) or solar electric technologies work. First used in about 1890, the word has two parts: photo, a stem derived from the Greek pho, which means light, and volt, a measurement unit.
So, photovoltaics could literally be translated as light-electricity. And that’s just what photovoltaic materials and devices do; they convert light energy to electricity.

Q: How do I know if I have enough sunlight for PV?

A photovoltaic (PV) system needs unobstructed access to the sun’s rays for most or all of the day. Climate is not really a concern, because PV systems are relatively unaffected by severe weather. In fact, some PV modules actually work better in colder weather. There is thus enough sunlight to make solar energy systems useful and effective nearly everywhere in the United States.

Q: How well do solar panels work in cloudy conditions?

A cloudy day provides sufficient diffuse light by which the panel will produce electricity. Optimum electrical production occurs with bright and sunny weather conditions. Under a light overcast, the modules might produce about half as much as under full sun, ranging down to as little as five to ten percent under a dark overcast day.
In remote, off-grid applications, a PV system is connected to a battery storage system as a backup power source. In grid-connected applications, the PV system works in parallel with the utility power grid. So, if electrical needs exceed the solar power output, the local utility makes up for the shortfall. Conversely, when the PV system generates more energy than the building requires, the excess power is exported to the utility grid, reversing the electrical meter!

Q. What is a solar water heater?

A solar water heater uses the sun’s energy to pre-heat household water before it enters the conventional gas (or electric) water heater.

Q. How hot can solar heated domestic water get?

Water heated by the sun can reach temperatures exceeding 212º F, but the normal temperature for household use is only 120º to 130º F.

Q. Are there different kinds of solar water heaters?

Solar water heaters are divided into two kinds of systems: active or passive. Active solar systems rely upon moving mechanical parts in order to transport heat, while passive units simply use the sun to accomplish this action.

Q: Are there any disadvantages to using solar energy?

The energy in sunlight can be used for many purposes, including heating water for a building or swimming pool. Using solar energy has many environmental and life-cycle economic benefits. However, solar energy heating or solar electric products often have higher “first costs” than other, similar products do. This means it will probably cost more initially to purchase and install a solar system than another kind of heating or electric system. Still, in nearly all cases, you will recover your initial costs through substantial fuel savings (as shown in lower utility bills) over the life of the product. Many solar systems last from 15 to 30 years.

Q: Can solar power be used to heat my home and business?

Yes – pre-engineered residential solar space heating systems are readily available to consumers today. But many solar energy professionals can engineer a system for you, on request. However, solar space-heating systems are considerably more expensive than solar water-heating systems. Depending on the size of the space that needs heating, a solar system could cost anywhere from $3,000 to more than $10,000. A solar energy professional in your area can explain what would be involved in purchasing this type of solar system. You may want to consider increasing your insulation and using passive solar technologies—such as large, energy-efficient, south-facing windows—as an alternative.

Q: What are the benefits of using solar energy to heat water in my home?

First, the fuel is free! Once you recover the higher initial costs of a solar system through reduced or avoided energy costs (that is, lower utility bills), your solar system will require expenditures only for maintenance. Also, when you include the cost of a solar water heater in a mortgage on a new home, the system often provides a positive monthly cash flow from the first day of ownership.
Second, solar water heaters and other solar technology applications do not pollute. They do not add to the carbon dioxide, nitrogen oxides, sulfur dioxide, and other air pollutants and wastes produced by most of today’s power plants, even those that run on natural gas. Solar water heaters also allow you to burn less natural gas in your home.

Q. Will solar heating affect how much water I will have? Will I have to change my bathing and cleaning routine?

Yes and No. You will actually have much more hot water than ever before. If the system is sized well for your family, you will no longer need to wait for the water heater to ‘recharge’ between showers.
Solar water heaters are always installed in addition to your regular water heater. That means that even during bad weather you will still have hot water. To maximize your savings, you should attempt to use the most hot water in the late morning and early afternoon when the solar system is operating at its peak. Also, it helps to spread your cleaning load over the week. For example, instead of washing seven laundry loads all at once it would pay to do one a day. This will reduce the amount your regular water heater must operate.

Q. How much do I save?

It depends upon the size of the system, the needs of your family and the way you currently heat your water. The average annual cost for water heating is usually over half the annual gas bill. Typically a person uses between fifteen and twenty-five gallons of hot water a day, which can cost $5.00 to $25.00 per person every month. A family of four could be spending between $384 and $1,200 a year just for heating water. A gas bill is charged at varying rates or tiers, and the most costly level or tier is levied in winter, when you are using the most gas. A solar system can reduce your daily gas consumption and thus you will be purchasing the less expensive Tier 1 or “Lifeline” rates.


JMT Mechanical, Air Conditioning Contractors & Systems, Concord, CA