FAQ and Glossary

Frequently Asked Questions

  • How do photovoltaics work?

    Here's a short answer: Photovoltaic modules convert Sunlight's photons to generate direct current (DC) electricity which is converted to alternating current (AC) by a device called an inverter, which is then wired into your main service panel where it feeds your internal power system.

  • How long will PV modules last?

    Based on industry in-field experience, laboratory test results and reliability testing, PV modules will last longer than 30 years in service provided proper care and regular maintenance are effective. However, manufacturer's warranty is generally given as 100% efficiency for 20 years, and at 80% efficiency for the next 5 years, totaling about 25 years performance warranty. But expected useful life of solar panels will be definitely 30+ years. Module failure rates are estimated at less than 1% over its whole life cycle.

  • How do I determine how large a system I'll need?

    The size of the system is usually directly proportional to the amount of power you use. As part of the proposal process Florance Energy Solutions will perform a site assessment, analyze at least twelve months' worth of utility statements, and raise the question of near-term (3-5 year) expansion and business plans. With that information, taking into account the specifications and limitations of the components, Florance Energy Solutions will present recommendations for your input and feedback, making sure you feel the ultimate path chosen is ideal for you.

  • Roof-mounted or ground-mounted?

    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, Florance Energy Solutions will present a solution that is optimized for your business and your needs.

  • What happens on dark/cloudy days?

    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, Florance Energy Solutions uses an annual production target, averaging out sunnier days with cloudy days. An electricity policy known as "Net Metering" - in practice in many other countries - smoothly interconnect the domestic solar (or any other renewable energy based) power production system with the local electricity power grid. Net-metering is yet to be implemented in India. Until that becomes a reality, our system will utilize a simple transfer switch which will allow for the smooth changeover from renewable energy to grid power and back.

  • Do I need batteries?

    Is back-up power critical to your business? If YES then you need back-up batteries. 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, Florance Energy Solutions can design a battery storage solution for your PV system to automatically switch over in the event of a power outage. Most customers inquire about batteries and ultimately choose to do without based on cost.

  • What rebates are available?

    Rebates vary from year to year depending on the funding for particular programs and the size of the PV system. Florance Energy Solutions will give you the most current information and include that in your proposal.

  • Is financing available?

    The best source of financing is usually the bank or finance company that you currently work with. If you like, we're happy to make arrangements with a number of independent mortgage brokers we've worked with on other projects.

  • 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?)

    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 5-7 years depending on the kind of government subsidy or rebate system in force.

  • Do you have a breakdown of this cost into individual components?

    Yes we do! The cost structure depends on the type of system - grid-tie or stand-alone.

    The primary driver for the difference in cost is the existence of a storage battery in stand-alone systems.

  • What are the critical assumptions for modeling ROI?

    The key drivers are savings from power no longer purchased and the value of any available subsidies.

  • How long will my installation take?

    This depends mostly on the size of the system, site access, and the distance between the array(s) and the main service. In general, allow a minimum of two weeks for each 3KW (Kilowatt) power system module to be installed.

  • What are the maintenance procedures and costs?

    Solar PV systems are solid state technology, 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.

  • Does cleaning the modules require any special expertise or equipment?

    A garden hose will typically do, though some customers prefer to use a high-pressure sprayer from the ground when the array is accessible.

  • What parts will break first?

    — If you have back up batteries system, then batteries would be the first causality, if not replaced in 5 to 6 years, as the batteries maximum life cycle is estimated as 7 years.

    — The inverter(s), which typically have a useful life of 15 years, will be the second thing to fail. Be ready to replace at the end of the 14th year.

  • What about rust and oxidization?

    All hardware is made for outdoor use and is made of either rust-proof stainless or galvanized steel or anodized aluminum which are highly corrosion-proof materials.

  • Someone told me that the energy required to make PV panels is greater than they will every produce. True?

    Glad you asked! We've heard this one before. Numerous studies indicate it takes 2-3 years to generate as much power as is required to manufacture photovoltaics, and the Environmental Working Group's Green Energy Guide reports an energy return on investment for photovoltaics of 9-to-1, greater than most other electricity sources (i.e., coal: < 8:1, wind: 5:1, nuclear: <5:1, biomass: 3:1).

  • I hear manufacturing PV panels creates toxic by-products and waste. True?

    Another good one, which we've also heard before. There's less documentation on this than the energy return on investment question, suggesting it's probably not an issue, but the Environmental Working Group's Green Energy Guide reports the manufacturing and operation of photovoltaics creates far less emissions than any other source of electricity analyzed.


  • STC Rating

    The Standard Test Condition (STC) is an instantaneous solar panel rating under controlled conditions. The Standard Test Conditions for a module are: solar irradiance of 1000 W/m2 , with the cell temperature maintained at 25°C and zero wind speed for cooling effect. These conditions are rarely, if ever, encountered in the real-world; therefore we have multiple other terminologies.

  • PTC Rating

    PTC (Performance Test Conditions) are defined as 1000 W/m2 plane-of-array irradiance, 20°C ambient temperature, and 1 m/s wind speed. PTC differs from standard test conditions (STC) in that its test conditions of ambient temperature and wind speed will result in a cell temperature of about 50°C, instead of the 25°C for STC. This rating was developed in an attempt to simulate real-world conditions. With elevated operating temperatures, the module/array produces less power, therefore the PTC rating of a module is typically 89% of the STC rating.

  • Inverter Efficiency

    Efficiency for an inverter can be defined as power-out divided by power-in. The inverter efficiency varies with ambient temperature, DC input voltage, and inverter's operating power level. [The California Energy Commission has created a "weighted" inverter test procedure to create a level playing field. This weighted inverter efficiency is known as the CEC inverter efficiency].

  • Inverter Power Rating

    This is the maximum output power rating of the inverter.

  • Inverter Maximum DC Input Current

    This is the maximum input DC current that should be connected to the inverter at any time. It is important not to exceed the maximum input current of the inverter as this may damage the components and will void the warranty.

  • Inverter Maximum DC Input Voltage

    This is the maximum DC voltage that can be applied to the inverter. Exceeding this value can damage the inverter. In the Selection Guide output results, the maximum input voltage is determined using the Open Circuit Voltage corrected for the user-selected minimum temperature.

  • Inverter Minimum Power Point Tracking DC Input Voltage

    This is the lowest voltage at which the inverter can continue its maximum power point tracking routine, which optimizes the power production. The inverter will continue to operate at voltages below this value, down to Minimum DC Input Voltage, but will not maintain the maximum power production.

  • Inverter Minimum DC Input Voltage

    This is the lowest DC input voltage for which the inverter can operate. In the Selection Guide output results, the minimum input voltage is calculated using the Max Power Voltage corrected for the user-selected maximum temperature.

  • Panel /Module Nominal Power Rating

    This is the nameplate rating or nominal output power of the panel under Standard Test Conditions. At higher temperatures, the PV panel will produce less power than its nominal STC rating.

  • Cell Temperature

    We use a standard 30°C as the cell temperature above ambient temperature for all calculations.

  • Lowest Ambient Temperature

    The lowest ambient temperature selection should be conservative and as close to the 30-year record for the system's geographic location. This temperature selection is used to adjust the open circuit voltage and ensure the inverter's maximum voltage is not exceeded.

  • Highest Ambient Temperature

    The highest ambient temperature selection should be conservative and as close to the 30-year record for the system's geographic location. This temperature selection is used to adjust the maximum power (operating) voltage and ensure the inverter does not shutdown due to low voltage during the hottest part of the day.

  • Strings

    A number of PV panels connected in a series circuit represent a "string". The maximum number of panels in a string is determined by the Open Circuit Voltage at the lowest temperature selected. The minimum number of panels in a string is determined by the Maximum Power Voltage at the hottest temperature selected.

  • Module Open Circuit Voltage

    This is an electronics term for the voltage between two points when they are not connected by a load circuit. This is typically the greatest amount of voltage that can be provided by a circuit to these two points.

  • Module Maximum Power Voltage

    This is the operating voltage point where a solar module delivers maximum power. The Maximum Power Voltage changes primarily with sun intensity and cell temperature. A grid supplementing inverter has a maximum peak power tracking routine which tracks the changing Maximum Power Voltage throughout the day.

  • Module Short Circuit Current

    This is an electrical term for the current between two points that are connected by load circuit with zero resistance (Circuit shorted). This is the greatest amount of current that can be delivered by a circuit.