FAQs on Photovoltaic (PV) Electric:
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Q. What is a Photovoltaic (PV) System?
A PV system allows you to generate your own power from the sun by
converting sunlight into electricity. It can generate energy to power
any electrical equipment in you home or office.
Q. What are the benefits of a Photovoltaic (PV) System?
- PV systems are a clean and efficient source of energy.
- PV systems decrease nitrogen oxides (the primary ingredient in smog) and greenhouse and acid rain gas emissions by reducing the amount of oil, coal and natural gas that are burned by electric utilities, thus improving air quality.
- Solar power saves you money every month by lowering your electric bills.
- PV systems utilize free energy from the sun to reduce the effect of future utility rate increases.
- You can enjoy energy independence by becoming your own power producer.
- PV systems also increase your property value.
Q. Why consider solar electric?
- Quiet, clean, zero emissions
- Robust, reliable, long life, and no moving parts
- Scaleable and now affordable with generous incentives
- Actual on-site generation… “Use What You Produce”
- Reduce electric bills and provide a hedge against inflation
- Back-up power for critical loads and energy independence
- Distributed generation is less vulnerable to disruption or attack
- Stable ROI’s of 6-12% for residential & commercial systems
Q. How does a PV system work?
A PV system works during daylight hours by converting sunlight into
electricity through solid state solar modules mounted on the roof of a
building or installed on the ground. Electricity created from the
system is supplemental to the power provided by the main utility grid
and is directed to a building’s main electrical panel. From there it is
routed to local loads and back to the utility.
Q. Do PV systems work better in hot or cold weather?
Systems in the northeast produce about 5-10% higher output than systems
in the southern U.S. because lower year round temperatures create lower
electrical resistance in the solar modules and other equipment.
Q. What is the durability of a PV System today?
PV modules today are based on proven technology and show little
degradation over many years of operation. There is a 25 year
manufacturer’s warranty and a 50+ year life expectancy on the solar
modules. This makes solar power a highly reliable source of power.
Q. Is this what people put on their roofs in the 1970’s?
No, the systems put on the roofs in the 1970’s were solar thermal
systems, heating hot water or air and were generally much less reliable
than today’s solar electric systems.
Q. Do we really get enough sunshine in the Hudson Valley for solar power to make sense?
Yes. Solar energy is measured in Peak Sun Hours per Day (kwh/m2 /day).
Los Angeles averages 5.6, Miami 5.2…and the Hudson Valley averages 4.5.
Solar module output is higher in colder temperatures which helps close
the gap further. Photovoltaics are proven in the field; dozens of
systems are operating now in the Hudson Valley. Customers are
generating a fraction to over 100% of their own power and demonstrating
6-12% year one returns on their initial investment.
Q. Where and how are PV solar modules installed?
Solar modules can be installed by being ground mounted on poles or
lumber, awning mounted on walls, or rail mounted on flat or pitched
roofs. The roofs can be asphalt shingled or made of steel.
Q. What does a site need to install a PV system?
The roof or ground area should be south facing and typically unshaded
between the hours of 9am to 3pm. The modules should be tilted 42°,
ideally, but 20° to 55° is fine.
Q. How do PV modules turn the sun’s energy into electricity?
The modules collect the sun’s energy and transform it into a direct
current (DC). The DC flows to an inverter which converts the DC to an
alternating current (AC), which flows into your electrical service
panel from where it supplies power to your home or office. If you
produce more energy than you consume it is automatically re-routed to
your utility’s grid and sold to them at the current retail rate.
Q. What is Net-Metering?
PV generation and purchases from the electric utility are “netted out”
automatically. This can slow down the utility’s meter or even spin it
backwards. If the PV system is producing more electricity than is being
consumed, the meter spins backwards, and the excess electricity is sold
back to the utility at the retail rate. Central Hudson will now permit
most customers with fewer than 15 kilowatts of PV to net meter.
Q. What are some of the financial incentives for installing a PV system?
New York State is strongly supporting the installation of PV systems.
- Sales tax exempt as capital equipment (ST-124)
- Systems under 50kw can qualify for NYSERDA (New York State Energy Research and Development Authority) rebates of $4,000 to $4,500 per kw (PON-716)
- NYSERDA Energy Smart Loan Fund can reduce borrowing costs by 400 basis
points (4%) - Systems under 10kw on residences can qualify for an income tax credit of $1,500 per kw up to $5,000 (IT-255)
- 30% Federal tax credit for commercial installments
- $2000 Federal tax credit for residential installments
- State rebates can total 60% of a PV system’s total cost!
Q. What are some important facts about the Hudson Valley regarding power and environmental concerns?
At the Indian Point Nuclear Power Plant, located on the Hudson River,
hot water which is used as a coolant for the reactors is dumped into
the River. This kills millions of fish annually and it is predicted
that the plant will produce approximately 2,000 tons of radio-active
waste by the year 2030. Also, some of the worst air quality in the
nation is located in the Hudson Valley as a result of coal-fired power
plants located along the river. It has been proposed for New York,
mostly along the Hudson River, in the New York City harbor, and on Long
Island, to install 65 new power plants which will further desecrate the
quality of air.
Q. How can a photovoltaic system be considered an investment?
A. Installing a PV system is a capital improvement to your home or
business (and is therefore exempt from sales tax). But unlike most real
property improvements, it generates electricity and thus an ongoing
cash flow, by directly reducing your electricity bills for the next 25
or more years. The initial capital investments and subsequent cash flow
benefits make a PV System comparable to other long term, purely
financial investments.
Q. Why should we consider putting some of our savings into a PV system?
A. Besides the obvious environment benefits, investing in a PV system
provides a unique opportunity to diversify away from financial markets
and their volatility. The rate of return from a PV system is
independent of interest rate fluctuations, accounting scandals,
recessions and international crises. In this way, it can provide a new
method to
allocate investment assets and improve diversification.
Q. What returns can be expected from a PV system?
A. The initial pretax return for a medium-sized system on a good site
is 8%-12% annually. That compares favorably to money market accounts,
CD’s, stocks and even long term treasuries. Initial returns can range
from 6%-12% depending on system size, site specifics and an investor’s
tax bracket. The initial rate of return can be calculated by doing a
solar site survey and system design before making a decision to
purchase a system. Average system pay back is 9-11 years.
Q. What is a microinverter? What is the Enphase Microinverter System?
An inverter is a power converter that converts direct current (DC) into
alternating current (AC). Traditionally, this has meant one,
centrally-located inverter converts all of the DC current from the
entire PV array into grid-compliant AC power. A microinverter is a
device that converts the DC output of a single solar module into
grid-compliant AC power. AC power then travels upstream through an
ordinary branch circuit to the service panel. The Enphase Microinverter
System consists of the microinverters as well as the Envoy
communications gateway and the Enlighten™ monitoring and analysis
system.
Q. What is an Envoy or EMU?
The Envoy (or EMU - Energy Management Unit) is the communications
gateway device which relays performance statistics from the
microinverters to the Enphase Enlighten website.
Q. What is the difference between an Enphase deployment and a traditional solar deployment?
The Enphase system provides improvements in the following areas:
- Productive
- Per-module MPPT maximizes energy production.
- Increases resilience to shade, dust and debris.
- High conversion efficiency.
- Increased system up-time.
- Greater production in low-light conditions.
- Reliable
- No single point of failure.
- Design reduces component stress.
- Very low internal temperature rise.
- Designed to NEMA 6P rating.
- Smart
- 24/7 monitoring on a per-module basis.
- Eliminates concern about where to place a large inverter.
- Dramatically reduces installation design.
- Modules can be mismatched and added as your requirements grow.
- Panels do not need to be collocated.
Q. Can Enphase Microinverters work in off-grid environments?
Enphase Microinverters have only been tested to work in grid-tied installations.
Q. How do Enphase Microinverters differ from PVAC units?
With PVAC, the inverter and module are a single unit and are sold and
installed as such. In contrast, the Enphase Microinverter is
architected as a standalone inverter. This modular design means that
the Enphase Microinverter offers the flexibility to work with most
off-the-shelf solar modules.
Q. Can Enphase Microinverters work with other DC power sources such as wind installations?
Enphase Microinverters have only been designed and tested to work in solar PV installations.
Q. Do Enphase Microinverters work in other geographic regions? Do you have plans for a version to support 50 Hz environments?
Enphase products are not currently certified to sell outside North
America. We are working toward broader compatibility, so please check
our website regularly as we will update our product information as our
plans progress.
Q. Can Enphase be used in both Residential and Commercial solar deployments?
Yes. Enphase Microinverters are designed for 240VAC residential, as well as 208VAC three-phase service.
Q. With which solar modules is the Enphase Microinverter compatible?
Please view the Module Compatibility List for a list of all modules
that work with the Enphase Microinverter. The Model M175 240V and Model
M175 208V work with 72-cell modules (24V nominal) up to 210-215Wstc.
The Model M190 208V and Model M190 240V work with 60- and 72-cell
modules up to 230Wstc. The Model M200 208V and Model M200 240V work
with 96-cell modules 32V nominal) up to 240Wstc.
Q. What PV connectors does Enphase Inverter support?
Enphase supports MC3 connectors referred to as our S01 or S11
(non-locking style) and MC4 connectors referred to as our S02 or S12
(locking-style).
How many Enphase Microinverters can be on a single branch circuit?
Following are the maximum Microinverters per branch circuit:
- M175 - 240V split-phase power - 16 Microinverters per branch circuit
- M175 - 208V three-phase power - 24 Microinverters per branch circuit
- M190 - 240V split-phase power - 15 Microinverters per branch circuit
- M190 - 208V three-phase power - 21 Microinverters per branch circuit
- M200 - 240V split-phase power - 14 Microinverters per branch circuit
- M200 - 208V three-phase power - 21 Microinverters per branch circuit
There can be an unlimited number of branch circuits per installation.
Q. Do all my modules need to match?
No. One of the advantages of a microinverter system is that it allows
for mixing modules. Unlike traditional inverters that are based on a
string installation, the Enphase branch circuit approach allows for
varying power output levels. This also means that end-user customers
have the flexibility of adding or changing modules over time.
Q. How many branch circuits (total) can I have?
The Envoy (EMU) can currently manage a maximum of 180 microinverters in
the 240V split-phase model. A 240V split-phase branch can have a
maximum of 16 microinverters, equivalent to a maximum of 11 AC branches
if those branches are fully populated.
Q. What is the minimum height above the roof that the inverters can be mounted?
We recommend 1" to avoid debris buildup between the roof and the inverter, as well as to allow for heat-dissipation.
Q. What type of junction box is recommended?
We recommend that you use a wet location-rated 2x4 j-box.
Q. What is the correct wiring for the A/C cable assemblies on the Enphase Microinverter System?
The A/C pigtail cable assembly terminates the first microinverter in a
branch-circuit to the junction-box. The four conductors' jacket colors
in the REV-1 cable for 208v three-phase are Black, Red, Orange and
Blue. When terminating the free-conductor end of the cable to the
junction-box, connect the cable's BLACK conductor to L1, connect the
RED conductor to L2, connect the ORANGE conductor to L3, and connect
the BLUE to Neutral. The Neutral line will need to be tagged with a
white piece of tape, marking it as the neutral, per the NEC.
Q. Do Enphase Microinverters work with a tracker system?
Yes, Enphase Microinverters work with tracker systems. The only
considerations are to ensure that the additional weight of the
microinverters does not affect the tracking mechanism's ability to
mechanically rotate, that the cables have enough slack, and the
grounding wires will accommodate the rotation of the tracker.