Frequently Asked Questions About Solar Photovoltaic (PV) Systems
Q: What is photovoltaics (solar electricity) or "PV"?
A: 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 phos, which means light, and volt, a measurement unit named for Alessandro Volta (1745-1827), a pioneer in the study of electricity. 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, as Edmond Becquerel and others discovered in the 18th Century.
Photovoltaic (PV): photo = light, voltaic = produces voltage
Photovoltaic (PV) systems, also referred to as solar electric systems, convert sunlight directly into usable electricity in your home or business using semiconductor technology. Sunlight strikes the PV cells and cause the electrons to flow, creating an electrical current (photovoltaic effect).
Q: How can we get electricity from the sun?
A: When certain semiconducting materials, such as certain kinds of silicon, are exposed to sunlight, they release small amounts of electricity. This process is known as the photoelectric effect. The photoelectric effect refers to the emission, or ejection, of electrons from the surface of a metal in response to light. It is the basic physical process in which a solar electric or photovoltaic (PV) cell converts sunlight to electricity.
Sunlight is made up of photons, or particles of solar energy. Photons contain various amounts of energy, corresponding to the different wavelengths of the solar spectrum. When photons strike a PV cell, they may be reflected or absorbed, or they may pass right through. Only the absorbed photons generate electricity. When this happens, the energy of the photon is transferred to an electron in an atom of the PV cell (which is actually a semiconductor).
With its newfound energy, the electron escapes from its normal position in an atom of the semiconductor material and becomes part of the current in an electrical circuit. By leaving its position, the electron causes a hole to form. Special electrical properties of the PV cell—a built-in electric field—provide the voltage needed to drive the current through an external load (such as a light bulb).
Q: What are the components of a photovoltaic (PV) system?
A: A PV system is made up of different components. These include PV modules (groups of PV cells), which are commonly called PV panels; one or more batteries; a charge regulator or controller for a stand-alone system; an inverter for a utility-grid-connected system and when alternating current (ac) rather than direct current (dc) is required; wiring; and mounting hardware or a framework.
Q: How long do photovoltaic (PV) systems last?
A: A PV system that is designed, installed, and maintained well, will operate for more than 20 years. The basic PV module (interconnected, enclosed panel of PV cells) has no moving parts and can last more than 30 years. The best way to ensure and extend the life and effectiveness of your PV system is by having it installed and maintained properly. Experience has shown that most problems occur because of poor or sloppy system installation.
Q: Can I use photovoltaics (PV) to power my home?
A: PV can be used to power your entire home's electrical systems, including lights, cooling systems, and appliances. PV systems today can be blended easily into both traditional and nontraditional homes. The most common practice is to mount modules onto a south-facing roof or wall. For an additional aesthetic appeal, some modules resemble traditional roof shingles
Q: Can I use photovoltaics (PV) to power my business?
A: PV systems can be blended into virtually every conceivable structure for commercial buildings. You will find PV being used outdoors for security lighting as well as in structures that serve as covers for parking lots and bus shelters, generating power at the same time.
Q: How do I know if I have enough sunlight for PV?
A: A photovoltaic (PV) system needs unobstructed access to the sun's rays for most or all of the day. Shading on the system can significantly reduce energy output. 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. Most PV modules are angled to catch the sun's rays, so any snow that collects on them usually melts quickly. There is enough sunlight to make solar energy systems useful and effective nearly everywhere in California and in the Philippines.
Q: How big a solar energy system do I need?
A: The size of solar system you need depends on several factors such as how much electricity or space you use, how, the size of your roof, and how much you're willing to invest. Also, do you want the system to supply your complete energy usage or to supplant a portion of your higher cost energy usage? You can contact Infin8energy, USA to determine what type of system would suit your needs.
Every site is different, and the needs of the system owner vary. System size depends on several factors, including how much electricity (kWh) is consumed on site and the orientation and tilt of the system, as well as available space and capital.
The first step is to determine the annual kWh consumption of the home or business. Once calculated, you can pinpoint avenues on how to reduce your energy consumption by implementing energy-efficient improvements, a necessary first step before installing solar. If you reduce your kilowatt-hour consumption, you may be able to install a smaller PV system, in turn allowing for lower up-front costs and a shorter payback period. Determine the annual cost of electricity from your electric bills to compute your savings with solar and your ROI on the system to be built.
Sizing your solar electric system appropriately is the key to a faster return on investment. The production of the proposed system should be parallel with the consumption on site and not oversized. Remember that you do not have to offset 100% of the consumption of your home or business. Offsetting any portion can be beneficial and a good way to get started with solar. A rule of thumb is to divide your annual consumption (kWh) by 1700 kWh/year (1kW of solar will generate about 1,700 kWh/year). This will give you an approximate system size to base your design on.
For example: The Smith residence consumes 6,000 kWh/year.
(6,000 kWh/1,700kWh = 3.5 kW)
This means that a 3.5 kW solar electric system would offset 100% of their energy consumption of the Smith residence. A: People decide to buy solar energy systems for a variety of reasons. For example, some individuals buy solar products to preserve the Earth's finite fossil-fuel resources and to reduce air pollution. Green advocates. Others would rather spend their money on an energy-producing improvement to their property than send their money to a utility company without any returns. Some people like the security of reducing the amount of electricity they buy from their utility, because it makes them less vulnerable to future increases in the price of electricity.
If it's designed correctly, a solar system might be able to provide power during a utility power outage, thereby adding power reliability to your home. Finally, some individuals live in areas where the cost of extending power lines to their home is more expensive than buying a solar energy system.
Q: How is a solar electric system designed, installed, and maintained?
A: You could install a photovoltaic (PV) or solar electric system yourself. But to avoid complications or injury, you will probably want to hire a reputable professional company with experience in installing solar systems, Infin8energy, USA, is your packaged solutions company. PV systems have few moving parts, so they require little maintenance. The components are designed to meet strict dependability and durability standards so they can stand up to the elements. However, they are fairly sophisticated electric systems, so installation usually requires the knowledge and experience of professionals.
Q: How much does a solar energy system cost, and how much will I save on utility bills?
A: Unfortunately, there is no single or simple answer. This cost depends on a number of factors, such as whether it is a stand-alone system or is integrated into the building design, the size of the system, and the particular system manufacturer, retailer, and installer.
It is also difficult to say how much you will save with a solar energy system, because savings depend on how much you pay your utility for electricity or natural gas, and how much your utility will pay you for any excess power that you generate with your solar system. You can ask your solar system provider how much your new system will produce on an annual basis and compare that number to your annual electricity to get an idea of how much you will save.
With Infin8energy, USA, we have a packaged solutions service that includes: consultancy & customer relations; assessment, analysis and design; engineering, procurement, permitting, construction and installation; monitoring and evaluation, after-sales service, products and insurance; available financing in addition to the total cost of the system depending on approved rate and credit worthiness. Our system costs are integrated into these packaged solutions that are very competitive with product and service standards in the Tier-1 level.
Q: What are the maintenance procedures and costs?
A: Solar PV systems are solid state technology, they have no moving parts and require no maintenance beyond cleaning, which can typically be done with a garden hose. Most systems should be cleaned 2-4 times a year, concentrated in the drier seasons. Systems in agricultural areas will likely require monthly cleaning.
Inverters are also solid state and require little to no maintenance beyond regularly checking the cooling fan outlets and cleaning when necessary. Mounting hardware is either aluminum or stainless steel and is rust-proof.
Q: What is net metering? Is net metering available where I live and work?
A: Net metering is a policy that allows homeowners to receive the full retail value for the electricity that their solar energy system produces. The term net metering refers to the method of accounting for the photovoltaic (PV) system's electricity production. Net metering allows homeowners with PV systems to use any excess electricity they produce to offset their electric bill. As the homeowner's PV system produces electricity, the kilowatts are first used for any electric appliances in the home. If the PV system produces more electricity than the homeowner needs, the extra kilowatts are fed into the utility grid.
Net meters look very much like other outdoor meters with one notable exception – they spin both forwards and backwards recording both the power produced and power used.
Q: Roof-mounted or ground-mounted?
A: It depends. Roof-mounted tends to be less expensive as they require no support structures and are most often not visible to passersby. On the other hand, ground-mounted systems can usually be oriented and tilted to optimize production. Through understanding your business and your needs, Infin8energy,USA, will present a solution that is optimized for your home or business needs.
Q: What happens on dark/cloudy days?
A: Unlike the early days of solar power when systems had to be sized for peak loads, a grid-connected PV system seamlessly switches to draw from the utility grid when needed. As such, we use an annual production target, averaging out sunnier days with cloudy days.
Q: Do I need batteries?
A: Is back-up power critical to your business? For most businesses, the answer is “no” and if you don't have a back-up solution today, an ordinary grid-connected PV system will leave you in the same position. However, if you require back-up power or are looking to upgrade your business's disaster preparedness, we can design a battery storage solution for your PV system to automatically switchover in the event of a power outage. Most customers inquire about batteries and ultimately choose to do without based on cost.
A backup battery bank can add as much as 25% in cost to a residential solar PV system. It’s not necessarily more efficient either – a same sized solar array will yield about 7–10% less energy if it’s battery-tied than its grid-tied counterpart.
Though you will remain tethered to your local utilities’ grid, you will not have to worry about not generating enough power. You also gain the advantage of offsetting rising utility costs. Most solar photovoltaic experts do not recommend adding a backup battery system unless there is concern about a long utility outage or the residence or business is in a remote location.
Q: I have plans for expansion. Can I plan for this now?
A: We frequently take into account future growth plans when designing your system. The choice of inverter can be influenced by near-term expectations about power usage and in some cases it may make sense to include excess capacity now and simply add more modules later. We'll discuss this with you and explore a variety of options to meet your needs now and in the future.
Q: I hear XXXXXXX's modules are the most efficient. Wouldn't those be the best choice?
A: There are some performance differences between manufacturer's products and often differences within a given manufacturer's product line. As you might expect, when a manufacturer introduces a product that performs better (i.e., greater power output per square foot), that becomes license to charge more for it. As such, there's an almost perfect correlation between price and performance, the best metric is cost-per-watt, rather than absolute performance. Available space may dictate the choice of higher efficiency modules, but in every case, Infin8energy and our partners seek to design the most cost-effective solution, maximizing your return on investment while minimizing the initial investment.
Q: How much weight will this put on my roof?
A: PV systems typically weigh no more than 3-4 lbs/sq ft, and most roofs can accommodate 2-3 times that amount of 'dead load' weight and your specific roof load capacity will be taken into account with our proposed design.
Q: Is financing available?
A: Yes, The best source of financing is usually with your Renewable Energy provider and the bank or finance company that you currently work with. Our packaged solutions services includes International financing (based on approved credit worthiness of business or individual) for up to 12 years with 50% to no (zero) money down.
Q: How much are these systems and how much money will I save each year? (Or, how long will it take to pay back my investment?)
A: The size of the system is the largest determinant of the price, and the savings rise accordingly. In most cases, the payback period for the investment in a photovoltaic system is between 5-7 years.
Q: What kind of county/city and utility company permits will I need?
A: We always need an electrical permit from the city or county and some require a building permit as well. We will handle all of this, from applications to inspections. Costs for these vary and are charged separately.
Q: How long will my installation take?
A: This depends mostly on the size of the system, site access, and the distance between the array(s) and the main service panels and release of permits. In general, the whole system takes between 60 to 120 days from contract signing to PTO, but it could also be less. Actual installation only requires a couple of days to complete for a 50 kW system. The design, approvals, permits and interconnection documentation processing takes most of the time.
Q: Will installation interfere with my normal business operations?
A: Most work is conducted on the site of the array installation (roof or ground) so your operations will likely not be impacted. We coordinate our efforts with your team, from deliveries, securing equipment, to crane usage. For example, we always schedule the final tie-in and Permit to Operate (PTO) around your schedule.
Q: Since the return on investment hinges on selling power to my utility, how can I be confident this will be accurately accounted for (Net Metering)?
A: The power you generate is metered by your inverter and the utility meter tracks power in both directions – both power you buy and power you sell back to the utility. Plus, you can track your production and the power you export via our online monitoring software. Finally, you'll receive a monthly statement from your utility company. All these provide ample reassurance that the accounting will be done, as it has been done for the nearly 15,000 interconnected photovoltaic systems all across California… and now in the Philippines.
Q: What are the critical assumptions for modeling ROI?
A: The key drivers are savings from power no longer purchased from your utility company. This is dependent on your previous electric costs and how much your system can offset from your current consumption which is normally between 5-7 years for most residences and 7-12 years for commercial and industrial projects with commercial electric rates.
Q: How can I use solar panels to power my house at night?
A: Battery storage may be ideal for some small scale PV systems. However, this method requires additional maintenance, and can be very costly. Most customers remain connected to the grid for access to continuous, reliable electricity at all times.
Basic PV Terminology:
DC: Direct current (produced by solar panels)
AC: Alternating current (used in the homes, business and industry)
Efficiency: Measure of how much of the sunlight is converted to electricity (%)
Capacity: Total amount of power that a system produces
Watt: Basic unit of power
Kilowatt: A unit of electrical power equal to 1,000 watts (most common measurement)
Kilowatt-Hour: Basic unit of energy. The use of 1,000 watts of electricity for one full hour (basic unit of electrical usage billing)
What is a watt?
The basic unit of power. Solar panels and lightbulbs are rated in watts.
What is a kilowatt-hour?
The basic unit of energy: Energy = Power x Time.
Example: If ten 100-watt lightbulbs are left on for one hour, the energy consumed is 1 kWh (100 w x 10 = 1 kWh).
How Does PV Work?
Photovoltaic (PV) systems convert light directly into electricity using semiconductor technology.
1. Individual photovoltaic (PV) cells are connected to panels. Solar panels convert sunlight into direct current (DC) electricity.
2. An inverter converts direct current (DC) into alternating current (AC) for electricity in the home.
3. The utility meter records the net amount of energy generated through the PV system. When you’re creating more electricity than you’re using, your meter will spin backward and the excess electricity is sent to the electric grid. This helps to offset the cost of your electricity usage at night or on cloudy days when your system is not producing electricity.
What are the components of my system?
Here is a list of components that may be included in your PV system.
1. Solar Panels/Modules – The tools to collect the sun’s power and produce direct current (DC) power.
2. Inverter – Converts DC power into alternating current (AC) power. AC power is what we use in our homes and businesses. Central and micro are the two types of Inverters.
3. Service/Utility Meter – This meter is a bidirectional smart meter that can keep track of any excess kWh production that you may send back to the grid.
4. Kilowatt-hour Meter – This meter keeps track of the kilowatt-hours your system has produced since the system was turned on. Note: Not all systems have a kilowatt-hour meter installed.
5. AC Disconnect - This is a device that the utility can use to turn off your PV system in an emergency or service situation. Note: Not all systems have an AC disconnect.
6. Conduit – Conduit is what the wiring for your PV system is housed in. Conduit is usually rigid piping such as EMT (electrical metallic tubing), flexible aluminum or PVC (polyvinyl chloride) piping.
7. Batteries – Storage system for excess energy if over-producing or for Off-Grid systems.
How efficient are photovoltaic modules?
Photovoltaic module efficiencies range from 5%, for some thin-film technologies, up to 19% for single crystalline (rigid) technologies. These percentages refer to the conversion efficiency, or the percentage of sunlight that is converted directly into electricity. Conversion efficiency is a critical issue when space is limited. The more efficient the module is, the less space that is needed to produce the desired amount of electricity.
Where should I put my panels?
PV panels can be installed on your roof or as a ground mount. Speak with your contractor about where on your property will yield the highest production. In California and in the Philippines, the ideal direction to have your panels face is south or west. If you live close to the coastline, a western-facing system may benefit you more than a south-facing system, due to the presence of the marine layer in the morning and stronger sun in the afternoon hours.
Do solar panels and inverters come with a warranty?
Your solar panels will come with a 25-year production warranty. Your inverter will come with a 10-year warranty. Most inverter manufacturers offer a supplementary 10-year extended warranty for an additional cost.