What all you should know before buying your Solar Energy Panels

What all you should know before buying your Solar PVs?

We all look forward to save on our energy bills. Solar Panels have provided us an effective, eco-friendly way of producing free energy from free Sunshine available to us. Solar panels absorb the sun’s rays and generate electricity or heating for our houses/ commercial establishments.

Solar modules use photons received from solar light to produce electricity through the photovoltaic effect. During the photovoltaic effect, light is absorbed by electrons present in atoms, this causes excitation of electron to a higher-energy state. Solar panel consist of photovoltaic modules. A photovoltaic (PV) module is an assembly (typically 6×10) of small solar cells. Solar PV panels run on photovoltaic system that generates and supplies solar electricity.

Each PV module is rated by its DC output power. This usually ranges from 100 to 365 watts. The efficiency of a module is determined by the area of a module given the same rated output – an 7% efficient 230 watt module will have twice the area of a 14% efficient 230 watt module. There are some solar panels, which exceed 19% efficiency.

A typical photovoltaic system consists of a PV panel, a solar inverter ( to convert the DC output produced by PV panels in to AC) , and sometimes a battery (to store the electricity generated by PV panels) and/or solar tracker (solar tracker orients a solar panels toward the), mount and interconnection wiring.

Things you should do before buying a solar panel system::

1.)   Calculate how much panel capacity will you need?

This will depend on your Daily Electricity consumption. You feed excess electricity generated by your solar panel to the common Grid. However feeding electricity back to the grid doesn’t make great earning though. So, you would like to maximise your own consumption of your solar PV energy rather than feeding in Grid or storing in batteries. Batteries too are expensive. So in order to be more cost effective you should assess your usage correctly and feed off less to the Grid or invest in expensive batteries.

Measure your electricity consumption pattern during daylight hours and calculate the required output of your PV system for your consumption. Please note that during the daylight hours you solar PV system will be working at its peak, so calculate accordingly. You can also have look at you previous electricity bill usage for this purpose.

You should choose the panels with higher rated output. But there are other factors too which might affect your decision. The biggest influencer would be the area available on you roof. The more area you have, more panels you can use to meet your energy requirement and this allows you the flexibility to choose from less costly and slightly less efficient solar PVs.

For Example for a 2000W array you can either use 8 250 W Jinko Panels or using the same are you can also use  eight 327W Sunpower panels and this will produce 2616W energy. Less number of panels will also be easier to maintain. Though the different company panels might have similar area but might vary in length and breadth so some of them might fit better on your roof if you have got space constraints.

2.)   How much do solar panels cost? / Budget

Depending on the budget you can decide to choose from following options:

The cost of solar PV system will depend mainly on the quality of panel used and system size, mount used and the batteries (If required). Apart from this there are other variables like using skirts, or tracking mount etc.

According to an agency the overall average cost of a fully installed 2.0kW system, was roughly $8000. But larger systems will cost more.

3.)   Check Space for Installation

How much roof Area you have available for solar pane installation. & ensure that there are no shading (Trees, other structures etc) on your roof where you are installing your solar panels. Though it matters little see that panels are facing a little southward direction to get maximum exposure to sunlight.

4.)   Approvals from local authorities

Check if there are any approvals are needed from local authorities.

5.)   Energy Efficiency-

Improve the energy efficiency in your home . Use only high energy efficient home appliances (Dishwasher, refrigerator, washing machine etc.) .Switch off lights and fans and other appliance when not required.

6.)   Calculate PayBack Time

Try to figure out your system’s payback time.You can do this by calculating the amount of electricity it will save per year and multiply that with current charges and add if you earn any feed in tariffs from exporting electricity grid. Divide this amount by your solar PV installation cost and you will get an approximate duration in years for payback time. Initially the payback time for typical solar power panel used to be 5 years but with the cut off in grid feedback rates it takes a little longer.

7.)   Are Solar Batteries required

In case you don’t have connection to common grid you should plan to install a storage battery, so that you can store your solar PV generated electricity for night-time use.

8.)   Multiple quotes means better deal

Get multiple quotes from installers to ensure you’re getting a good deal.

9.)   Owning or Renting?

Consider solar leasing and power purchasing agreements, in case you cannot afford solar Pv installation immediately.

10.) Check Accreditation of installers

Make sure the installer is accredited by the competent authorities and that the panel meets the required standards.

Solar PV Technology ::

The monocrystalline panel is considered the original solar PV technology. But with changing times technology new trends are emerging and various new products available I market now.

Factors driving innovations are price, efficiency and versatility. Polycrystalline silicon Solar PV modules & thin-film solar PV technology, are providing a variety of option to residential, commercial, industrial establishments to meet their solar energy demands.

PV solar technology uses silicon to generate an electrical current when silicon absorbs sunlight, it regenerates electricity through photovoltaic effect. Solar PV technology requires purified silicon to achieve the maximum efficiency, and the price of Solar PV is primarily determined by the crystalline silicon purification process it uses.

1. Monocrystalline Solar Panels: (Best Quality)

Monocrystalline silicon solar PV is considered as the most efficient system with respect to the wattage output compared to Panel size. But also at the same time these are most expensive panels too.

Your next best bet is the polycrystalline silicon solar PV panels. These offer efficiency levels close to monocrystalline panels, but cost wise are nearly half of them.

Monocrystalline solar PV are produced from a single crystals. Monocrystalline cells are manufactured from artificially synthesized crystals which are grown in isolation and thus making them nearly 35% more expensive that polycrystalline cells. Also these are most efficient having efficiency rating between 17-24%.

Monocrystalline crystals are usually grown in oval shape and they are cut into very unique shapes and can be easily recognised. You can tell by missing corners in the sliced silicon cells. Monocrystalline PVs have even crystal framework which renders it steady blue color with no grain marks. This is considered most pure and renders highest efficiency levels.

Polycrystalline PVs may have better temperature tolerance. The differences in color or heat tolerance may be because of the manufacturing processes involved each case. Solar panels are a complex combination of various parts and overall performance of the PV may depend on more than one factor of than only the type of cell we use.

2. Polycrystalline Solar Panels: (Good Value)

Polycrystalline Silicon PV cells are manufactured from thin wafers made from artificially grown crystals. Polycrystalline cells are manufactured by pouring molten silicon into a cast. However, the crystal structure thus formed will have imperfections creating boundaries where the crystal formation breaks. Thus giving it an appearance of multiple interlocking silicon crystals grown together. Polycrystalline silicon has distinctive, grainy appearance, and have a pattern which highlights the boundaries in the crystal.

Although polycrystalline silicon is cheaper  but is considered less efficient when compared with monocrystalline because of its  impurities. Polycrystalline Cells are more economical as its manufacturing process uses less energy and materials, which give it considerable cost advantage over monocrystalline silicon. Polycrystalline PV’s efficiency is lower than the monocrystalline solar cells, currently at 15-20%

3. Amorphous Solar Panels: (Thin Film)

The advantage of Thin-film solar PV are its portability & its light weight .Although it has the lowest market share , the thin film technology is comparatively newer and it is a good option for projects with lesser power requirements that need portable and light weight Solar PV. It has a record of maximum efficiency of 20.3% , where they used most common material amorphous silicon at 12.5%.

Thin-film panels can be made  from a variety of materials, like amorphous silicon (a-Si), cadmium telluride (CdTe) &  copper indium gallium selenide (CIS/CIGS). the most prevalent type used is amorphous silicon. Thin film solar cells are made from a thin layer of photovoltaic material (such as amorphous silicon etc.) on a base plate of glass, metal or other substance, During the process of constructing Thin Film cells, instead of using crystals, silicon is deposited very thinly on a backing substrate like glass , metal or other suitable substance. Here the layer of photovoltaic material (sliicon etc) is so thin that it allows a huge level of flexibility. Also these prove to be more efficient in low light levels (like in winters)

Thin-film cells are supposed to become less expensive and research is going on. Thin-film have the potential to be the driver in the consumer market driven by price consideration. Also thin film technology is evolving and promises to be highly useful in more flexible applications than standard solar panels. So far has been generally less efficient and is very rare on rooftops. However it’s used in various applications, like building-integrated PV systems, solar-powered calculators & garden lamps etc.

Thin Films have lowest efficiency (8-13%) rating amongst all three types of solar PVs. Also these are not robust as Monocrystalline or Polycrystalline PVs..

4. Other Variants

    a.) Hybrid Solar Cells

Hybrid solar cells are a combination of monocrystalline & amorphous solar cells together. Also known as HIT solar cells (Heterojunction with Intrinsic Thin Layer). HIT have higher efficiency ratings than any of the other Solar PVs alone. Another advantage is that these are better suited in sunnier climates too, where temperatures often exceed 25⁰C. HITs create up to 10% more electricity in these conditions.

Interdigitated back contact solar cells (IBC), or rear contact solar cells, are a variant of standard solar cells. These achieve higher efficiency by placing all the electrical contacts on the rear of the cell, usually other panels have it at the front). This ensures that there are no metal contact strips which may prevent light getting to the cell surface. Rather than another type of cells it is more of a variant of a circuit engineering technology.

 b.)BIPV (Building Integrated Photovoltaics)

BIPV’s as the name suggests look like real roofing tiles .But these are costly and are considered less efficient than conventional PVs. You need to have a big spacious and sunny roof to actually the difference in your electricity bills. Also the durability of these are questionable and these do not last as long as regular panels.

Solar Thermal Panels (Not to be confused with solar PV Panels)::

Solar thermal panels have nothing to do with electricity. Solar thermal panels produce hot water for your home/ pool. You can save some bucks here, Instead of paying the gas company to heat your hot water tank use solar thermal Panels, .

Some solar thermal systems can also provide heat and air conditioning.

Solar photovoltaic (PV) cells and solar hot water systems work in completely different ways. Solar PV cells convert solar energy into electricity, while solar thermal panel’s water uses the sun’s energy directly to heat liquid, with no electricity involved.

     How solar thermal panels work

Solar heating systems use solar thermal collectors. These are normally thin, flat boxes, mounted on the roof facing the sun. Sunlight gets into the box through a transparent cover. There are tiny tubes inside that carry water into the box to be heated. There is also an absorber plate, painted black, which helps in making liquid hotter.

The thermal collector sends the hot water into a storage tank which is well insulated to preserve heat. Some systems use gravity to do this( way more sustainable) but most of the systems use pumps .Systems using gravity are called  “passive systems,” If the system uses something other than water in the solar collector, that hot liquid heats the water using a coil of tubing.

Efficiency of Solar Panels :: 

Solar PV’s efficiency is measured by it’s electricity output (in watts) with respect to it’s surface area. Higher the efficiency, more power you will get from a given roof area, This may also means that you  have  lower installation cost as the fewer panels will have to be installed to achieve the desired electricity output.

In case you are having plenty of roof space, you may buy cheaper panels with lower efficiency and use more of them to meet your energy demands.

Please note that solar panels become less efficient as they get warmer, due to the physics of the photovoltaic effect. So you may get less power from the panels on a very hot day than on a normal day .Also to put the facts right, even on a 25°C day, your solar PVs might be operating well above 40°C.

It is important to note that Solar panel power ratings are based on standard conditions (that is on 25°C panel temperature). Some panels have better temperature tolerance than others (for example HITs) and should be preferred in hot climates.

Panels should be installed correctly to allow air to circulate underneath the Panels to keep them cooler.

Polycrystalline silicon is estimated to be the market leader with the market share with 55% of PV technology shipments in 2013, compared with 36% for monocrystalline, according to the U.S Department of Energy

With the latest technology inventions, we have polycrystalline cells with a maximum efficiency of 20.4% and monocrystalline cells at 25%.

Space and area are often a key considerations for implementation of any solar power project. Usually the project are sought for home or a solar farm for a grid-connected utility, This makes module efficiency a critical element for project installations.  While most solar panels range in 13 to 16% efficiencies, some very high end modules reach as high as 20% efficiencies.

Mono or polycrystalline solar PV are established technologies and largely provide the right combination of price, efficiency and durability and are used in most of the installations. Crystalline silicon is considered the best and standard for even commercial and industrial use as well.

 

Components of Solar PV System :: 

Basic components of the Solar PV system are as follows-

1.  Solar Panels:

Solar PV Panels are the main part of the entire system and their placement and mounting affect the performance of system more than any other component. Also these are most costly parts .Normally it ranges anywhere in between $2.5 to 5$ per watt.

2. Mounting equipment: 

Mounting equipment is of critical importance. Mounting the solar is so important because first it should ensure that PV panels are getting maximum exposure to sunshine in all season and second it has to have sufficient integrity to stay put for 25 years or more.

3. Solar PV inverters (DC-to-AC):

Electricity produced by Solar Panel is direct current (DC)& the electricity we use in our homes is alternating current(AC). Therefore solar convert the DC electricity produced by solar to usable AC (usually 120 VAC or 240 VAC) . Which can be used in home or can be sold back to the grid as well. Inverter may cost $0.7 onwards. However inverters are not high on durability and that’s why you should choose the best quality available.

There are 2 major types of solar inverters:

       a.) String inverters (Or Central inverters) 

String inverter is attached to a string of solar panels. Each string of panels is attached to a string Inverter. So the string inverters converts DC to AC fo use in Home and to sell to the grid. However the main drawback of string inverters is that if one of the panels in the string fails or produces less electricity (because of shading, dust), this affects the output of all the panels. All the panels will operate at the output of the worst panel, so a small amount of shading or debris on any of the solar panels can disproportionally reduce the total output of entire solar PV system.

Also string inverters have comparatively shorter lifespans to micro inverters. String inverters are need simple wiring and you can use thinner wires which can make your system cheaper. Also it reduces cost because of the fact that you need to buy fewer String inverters than multiple micro inverters.

However we would recommend Micro inverters simply because of the fact that single panel’s inefficiency doesn’t affect the whole system’s output here.

         b.)Micro inverters 

These are a newer technology. Micro inverters are attached to each solar panel individually. Therefore each panel has its own micro inverter and acts as an individual power station.  As a result, micro Inverters do not suffer the same performance reduction as a result of underperformance of single panel as every single panel is managed by its own individual micro inverter. So underperformance of a single panel has little effect on the combined power output from the entire solar PV system.

Micro inverters are more expensive than the string inverters, obviously because of the fact that you have to use more of them. However whatever extra you spend on, that is compensated by it’s increased performance (Micro inverters produce 25% more power than String inverter). Also added to their advantage is the fact that they are more durable than string inverters (warranties may extend up to 25 years for micro inverters.)

       Buying inverters for your solar PV system

While buying solar inverter you should try to get inverter which can match the AC output to that provided by utility companies. Inverters which provide modified sine wave signal are usually cheaper. Waveform like modified sine wave & pure sin waves represent the quality of AC signal that inverter produces. Inverters which produce pure sine wave signal, are slightly more expensive. Some appliances (like computers) simply won’t work unless they are provided by a pure sine wave signal, We strongly recommend strongly that you should try to get this type of inverter.

Grid tie inverters require AC pure sine wave signal to be perfectly in sync with the waveform from the grid. These may be more expensive than the typical inverters as they also have a built in safety feature to automatically switch off power from the solar array if the electricity grid goes down for any reason.

MPPT-Maximum Power Point tracking installed within inverters, help to maximise the electrical output of your solar PV system. MPPT extract the maximum power from the photovoltaic (PV) module by making them operate at the most efficient voltage (known as the maximum power point voltage). MPPT inverter compares the output from the PV module with the grid voltage and then modifies it at the most efficient voltage, to allow maximum export of electricity back to the grid. Generally a typical MPPT charger in solar PV system will improve power gain by 20-45% in winter and 10-15% in summers.

4. Tracking mounts:

Tracking mounts are mean to mechanically move the PV panels over the course of a day to ensure the solar PVs directly face the sun at all times. We have dual axis trackers which change both azimuth and elevation, while single axis trackers only change the azimuth.

5. Disconnect switches:

Disconnect switches are critically important for safety reasons. In case any abnormal pattern happen in you electrical systems, you should shut off the solar system first. Disconnect switches should be mounted in a place where it is easily reachable. Every member of family should know how to switch off the Solar PV system as a safety precaution.

6. Wiring and fuse box connections:

Wiring, conduit, and connections to your household main fuse box takes most of the time while installation, though these may not cost as much other parts of the system.

7. Utility power meters:

Solar customer use TOU-Time f use rate structure which requires digital meters. Conventional power meter are not used here as it requires more intelligent processing which pure mechanical devices are not capable off

8. The battery:

You need solar batteries to keep a backup when your solar PV system is not producing electricity like at night when there is no sunshine, in times of grid blackouts or if you want to go off-grid.
Batteries store the excess electricity produced by your solar PV during daytime and keep it is ready for your use at night. This way it allows you to use you solar PV electricity twenty cross seven.
Though solar PV batteries use deep cycle lead and look similar to car batteries but are structurally very different than those. Most popular types of batteries  are GEL and AGM ( Absorbed Glass Mat) , These batteries do not degrade fast and store the charge quite well. Both types of batteries can recharge 80% of their capacity a multiple number of times.
An automotive battery is a shallow-cycle wet lead battery, and is designed to discharge only about 20% of its electricity, therefore it is unsuitable for solar PV set-up. This is because if 20% more electricity is withdrawn a few dozen times, it will get damaged and cannot be used no longer.
Solar photovoltaic batteries usually operate at 12 volts, and multiple batteries can be arranged together to form a battery bank. This can augment the storage potential of your solar PV system.  A bank of batteries is organised in a ‘series’ to increase the capacity of your storage but it also increases the voltage delivered from the bank,. On the contrary if multiple batteries are organised in a ‘parallel’ circuit increase the capacity, but also keep the voltage the same .Usually mains electricity runs at higher voltage, so if you are connected to a grid tie system it is likely that you will try to match this by running the batteries in series).

9. Solar Charge Controllers/Solar Charge Regulators:

Solar Charge Controllers are used in solar PVs to prevent the batteries from being overcharged. If you are using ‘grid tied’ system, a solar charge controller is not necessary, as any excess electricity is directly sent to the grid.
However, for any other setups which are not tied to grid, solar charge controllers are necessary.  of the other three setups, a charge controller is necessary; it acts to regulate the flow of electricity between the solar PV modules, the batteries and appliances (called as the load).
When the load is drawing power (like when AC is on), the charge controller allows electricity to flow from the solar panels directly (when the sun is shining), or from the battery, or from a mixture of the two. The solar charge controller also prevents damage to the battery by monitoring the flow of electricity in and out. For example if your system overcharges the battery, or completely discharge all the charge held within the battery, it will damage it in both the cases.
Solar charge controller prevents reverse current flowing from the batteries back into the solar panels during night when solar PV are not producing electricity.
Solar charge controllers also are equipped with highly effective charging programs that maximise the charging speed, while still preventing overcharging. The maximum power produced by the solar photovoltaic module is dependent on the amount of sun hitting the solar cells and the temperature of the cells.

What kind of Solar array mounting do you need?

Mounting is very important as electricity produced is directly proportional to the sunshine hitting you Solar PV panels. There are basically 3 types of mounts-Fixed, Adjustable & Fully automated mounts.   It is important to mount solar panels in a way to maximise the amount of light that they receive.

1.) Fixed solar array mountings

This is the most basic mounting and requires very less monitoring for maintenance. These are most economical and do not move at all. So its imperative that you install them in way to gather maximum exposure to sunshine in all weathers. Preferably facing equator, slightly tilted to south direction in northern hemisphere. Fixed racks hold modules stationary as the sun moves across the sky. Most of the fixed racks are set on poles above ground.

2.) Manually adjustable solar mountings

As their name suggests  you can adjust them , usually a few times in an year when the season changes. Sunshine angle is slightly different in summers and winters, So you can adjust the angle of your solar PV to minimise reflection and maximise absorption in different seasons.

3.) Fully automated tracking solar mount

These mounts are most advanced and most expensive of all three munts. Fully automated tracking mounts track the sun and keep on adjusting the angle of Solar PVs to maximise the sunshine exposure and thus the electricity produced. These are by far most efficient and constantly moving. Despite of al the efficiency claimed by this system it is more cost effective if you add an extra panel to your array and used the fixed or adjustable mountings.Solar trackers increase the amount of energy produced per module at a cost of mechanical complexity and need for maintenance.

Apart from the above we have other kind of mounts as per the requirement of the client-Ground mounts and Roof Mounts.

i.) Ground mounted Solar PVs are usually large solar power plants. These solar modules are held by frames which are attached to ground base mounting supports.

Ground based mounting supports consist of following:

• Pole mounts-These are driven directly into the ground or embedded in concrete.
• Foundation mounts- such as concrete slabs or poured footings
• Ballasted footing mounts- These have heavy concrete or steel bases to secure the solar PV system in position and thus do not require ground penetration. This is well suited for place where ground penetration is not possible or restricted, such as capped landfills. This also renders simplified decommissioning or easy relocation of solar PV systems.

ii.) Roof-mounted solar power systems have solar PVs held in place by frames attached to the roof-based mounting supports. These include following:

• Pole mounts-Here the pole mounts are attached directly to the roof structure and could use additional rails for attaching the module racking or frames.
• Ballasted footing mounts- Ballasted footing mounts use heavy concrete or steel bases to secure the panel system in position and do not require through penetration. This mounting method also renders simplified decommissioning or easy relocation of solar PV systems with no adverse effect on the roof structure.

All wiring connecting adjacent solar modules to the energy harvesting equipment must be installed according to local electrical codes and should be run in a conduit appropriate for the climate conditions

What you should keep in mind while mounting Solar Panels?

Warranty period for solar panels

Solar panels should last 25 years and beyond. So you should look for those products which offers warranties this long. Now there is performance warranty and Product warranty, Usually the performance warranties range upto 25% with 80% performance of its claimed power rating and product warranties range upto 12 years.  Sunpower is and exception which offers 25 years warranty on both performance warranty & product. Also they offer higher performance criterion in the warranty.

Some installers may also give warranties for the mounting frame, workmanship and so on. Look for the best and go for quality.

Questions to ask your energy retailer before installing solar

• What is the FiT (Feed in Tariff) you’ll be paid and how often will you get it? How will you receive it: as a discount off your energy bill or as a standalone cash payment?
• Will you need to change to a new meter and what will it cost?
• What is the cost of the electricity you purchase from your retailer (in cents per kWh), and will you lose your off-peak rates if you install solar?
• Will you be charged a higher daily fixed charge if you connect your solar PV system?
• Do you have to pay any additional fees?