The Anti-Solar Panel

There are different kinds of solar panels. The most typically used is a type that generates electricity from the sun through a physical process called the photo-voltaic (PV) effect – when light exposure on certain materials generates an electric current. Another kind of solar panel is the one that inspired a team of researchers at Stanford University in Palo Alto, California to develop a new system that can harness energy in darkness. It’s based on the concept of using heat to generate energy but an inverse version of the solar panel. While the solar panel uses the heat difference between the sun and Earth with the Earth being the cooler side – their system makes use of the heat difference between the coolness of the night atmosphere and the Earth with the Earth being the hotter side. 

Named as “anti-solar panel” by some, the device has the potential to bridge the gap left by solar energy, collecting energy from the night sky. The thermoelectric generator-based device harnesses the variance in temperature between Earth and outer space by using “a passive cooling mechanism known as radiative sky cooling to maintain the cold side of a thermoelectric generator several degrees below ambient.”

The researchers have only tested their system with a very small prototype. The device was a 20-centimeter (8-inch) aluminum disk painted black and hooked up to commercial thermoelectricity generators. It successfully created enough energy to power a single small LED lightbulb–a small success with immeasurably massive potential. It’s even possible that the device could act in reverse during the daytime, absorbing sunlight and producing electricity from a heat travelling from the sun to the disk and into the outside environment.

For now, this device doesn’t come close to the energy harvesting abilities of a solar panel but the technology is still only in the research and development stage. The researchers have already planned improvements including enhanced insulation around the top plate that could potentially raise the device’s energy production to 0.5 watts per square meter or more, and this is only the beginning.

Once they are able to refine the system to produce anywhere close to as much energy as a standard solar panel, it could completely transform the renewable energy sector. It’s cheaper to make and can provide a way to generate electricity at a time that solar panels can’t.

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SKY- Suryashakti Kisan Yojana

The Gujarat government on Saturday launched a solar power scheme for farmers- Suryashakti Kisan Yojana (SKY) enabling them to generate electricity for their captive consumption as well as sell the surplus power to the grid and earn an extra buck.

Announcing the pilot project of the scheme in Gandhinagar, chief minister Vijay Rupani termed it a revolutionary step towards empowering farmers to generate their own electricity using solar energy and help doubling their income.

As per the scheme, farmers having existing electricity connection will be given solar panels as per their load requirements. The State and Central governments will give 60 per cent subsidy on the cost of project. The farmer is required to take 5 per cent cost, while 35 per cent will be provided to him as an affordable loan with interest rates of 4.5-6 per cent. The scheme duration is 25 years, which is split between 7-year period and 18-year period.

"For the first 7 years, farmers will get per unit rate of Rs 7 (Rs 3.5 by GUVNL + Rs 3.5 by state govt). For the subsequent 18 years they will get the rate of Rs 3.5 for each unit sold," said Saurabh Patel, State Energy Minister.

The move is being seen as an attempt to pacify the farmers, who are reportedly angry with the ruling party.

Below is the link for the media session of Gujarat CM for announcement of Suryashakti Kisan Yojana, click here. To know more about subsidy, read MNRE Rooftop Solar Power Plant Subsidy Scheme.

What is 1 kW ?

What does 1 kW means? For many it is quite simple but in reality it is not. As per definition, 1 KiloWatt is a unit of energy which transmitted or used at a constant rate (power) over a period of time. The total energy in kilowatt hours is equal to the power in kilowatts multiplied by the time in hours.

When we are talking in reference to solar system then, 1 kW can be expounded in two way- 1 kW AC and 1 kW DC. There is difference between 1 kW and 1 kWp. Actually, 1 kW means 1 kW AC which is general is  misconceive as 1 kW DC. 1 kW  DC is  represented as 1 kWp. 

1 kW AC is 1000 watts of AC power generated by converting DC power through Solar Inverter. It is equal to capacity of Solar Inverter. On other hand, 1 kWp mean 1000 watt of DC peak power. It is maximum DC power generated by solar modules and is equal to total capacity of solar modules.

Example: 308 nos. of 325 Wp solar panel with 2 nos. of 50 kW solar inverter. In this case, DC capacity would be 100.10 kWp and AC capacity would be 100 kW. The difference is noticeable through above example. The ratio of DC capacity to AC capacity is called over-loading or under-loading.

So, next time if someone says 1 kW, do question him/ her  whether he means AC or DC.

South VS East-West orientation

The sun as we know rises in east and sets in west. Additionally, it also changes is position (season wise) in sky with respect to a fixed point on earth. The orientation of solar module may be defined by two parameters namely azimuth and tilt angle. Tilt angle of solar module is defined as angle between the horizontal ground and the solar module. Azimuth angle of solar module is an indicator of alignment of the module with respect to (true) south. For modules facing (true) south this angle is Degree and for module facing (true) north this angle is +/- 180 Degree.

The most common methodology of module orientation and the most efficient one wherein the module is oriented in southwards direction. With southwards orientation, sun can be tracked to its maximum limit, thus generating maximum energy. However, a major drawback with this type of orientation is that it requires a larger area and also leads to shadow losses. To reduce shadow losses, system needs to be designed in such a way that no solar plates in one row cast a shadow on another at any point of time. With this orientation, the tilt angle widens, increasing the pitch and reducing the available space. Modules installed in southward orientation are favorable for places with high energy demand. 

East- west orientation of modules is the best method to optimally utilize the available space. On flat roofs, this orientation has the capability of maximizing the number of PV modules in a way that they don’t cast a shadow on each other. Through this method, solar PV systems can be installed on East-West-oriented (E-W) or slanted roofs as well.

Advantages of E-W Orientation

• More Installed Capacity

Over 20-30 percent more capacity can be installed in the given area. This is because only walking space is left between the arrays instead of shading elimination.

• Higher yield per sq. m

Since higher capacity installed in a given area therefore there would be higher yield.

• Even distribution

The generation of east facing modules would be a mirror image of modules facing west. This would form a bell curve, distributing the generation evenly.

Advantages	Disadvantages
More Capacity in specified area	High mismatch losses
Higher generation per sq. meter	Lower specific production
Even distribution of generation	Increase in number of inverter
Reduction in Wind Load	Lower Return on Investment

Below are the results of simulation run through PVsyst:

E-W Orientation

South Orientation

To conclude it is important to check and verify the feasibility of the orientation used in module installations. Before finalizing the orientation, it is critical to understand the load profile calculations and building architecture. In case of a challenging building architecture and energy demands/costs, East-West orientation may fetch attractive results. It is true that E-W orientation substantially increases the DC capacity of installations by nearly 33 percent on the same size of roof than southward orientation and also results in considerable amount of power generation. E-W orientation can definitely prove to be a useful method in harvesting solar energy on challenging rooftop structures.

GRIHA: Renewable Energy Utilization- A step towards sustainability

GRIHA is an acronym for Green Rating for Integrated Habitat Assessment. GRIHA Council, is an independent platform (registered as a society) for the interaction on scientific and administrative issues related to sustainable habitats in the Indian context. GRIHA Council, is mandated to promote development of buildings and habitats in India through GRIHA. It was founded by TERI (The Energy and Resources Institute, New Delhi) with support from MNRE (Ministry of New and Renewable Energy, Government of India) along with a handful of experts in the sustainability of built environment from across the country. 

In this blog we will be discussing on Energy section of GRIHA out of may other section which will include points and ways to sffirm them."Renewable Energy Utilization" criterion is a part of Energy section. The purpose of of this criterion is to ensure that building incorporate renewable energy as a source in the project and partially or completely get independent from the conventional source of energy such as coal petroleum etc. By fulfilling the criterion, a project can claim maximum of 7 points.  This criterion contributes 7% of total points.

In order to claim points in this criteria, a project has to meet below mentioned conditions:

• On-site/Off-site renewable energy system installation to offset a part of the annual energy consumption of internal artificial lighting and HVAC systems as mentioned in the table below: 

Daytime Commercial/ Institutional Buildings	Residential Buildings	24 X 7 occupied buildings	Points
2.5% (only On-site)	-	0.5% (only On-site)	Mandatory
5%	5%	1%	1
10%	10%	3%	2
15%	15%	5%	4
20%	20%	7%	5
25%	25%	10%	7

                                                                             OR

• Off-site renewable energy system to offset 100% building energy demand (this appraisal is available for only non-residential buildings) – Mandatory +7 points 

If the project is meeting the above mentioned conditions, following documents has to be submitted. The nature of documents can change but the purpose needs to be fulfilled in order to claim points

• Calculations/simulations for renewable energy system sizing & on-site annual energy generation potential. 

• Specification sheets and purchase orders (reflecting full quantities) of the renewable energy system, highlighting the panel performance (as tested under standard test conditions). 

• Drawings in CAD format to show location of renewable energy systems. 

• Documents supporting off-site generation of energy through renewable energy systems. These may be either: Renewable Energy Certificates (RECs) for at least 2 years along with a declaration that the RECs are not being used for any other obligatory requirements and will be purchased every year OR Power Purchase Agreement from the utility for purchase of green power. In the agreement, the address of the particular site must be mentioned. 

• Photographs, with description, of the measures implemented.

For more details on green building and its other criterion visit GRIHA website. To download copy of GRIHA manual V 2015, click here