Expert Energy Solutions

Skybless provides consultancy services to residential and shared commercial buildings in cities to deploy roof top solar for powering the common utilities such as lifts, pumps, lighting. The same infra, can now power the electric vehicle charging stations that Skybless would help set-up in these buildings.

There are certain hurdles which restrict the urban residential and commercial buildings to benefit from clean energy opportunities. The affairs of these buildings is run by bodies known as society managing committees or RWAs comprised of residents/occupants who work on a voluntary and honorary basis. Unlike an industrial or large office establishment, they lack in-house engineering or maintenance resources, domain knowledge, time, skills, and tools to plan for and later manage any complex energy infra.

The organised EPC players in clean energy infra space have stayed away from the above segment due to its scattered nature, combined with small capacity denominations (sub 50 KW) and prolonged decision-making process. This segment is by and large seved by un-organised players, who mostly do not have the requisite knowledge, tools and a professional set-up to plan, deliver and manage high quality energy infra systems.

Skybless addresses all these gaps and goes beyond to advise on the full range of clean energy benefits to the Urban Buildings encompassing clean energy generation, storage, serving new use cases such as charging for electric vehicles and all of this in both CAPEX and ‘CO-INVEST OR CAPEX-FREE’ models.

Solar can power the common utilities in your building such as lifts, water pumps, common lighting, and others. If your electricity consumption on common utilities is more than 2000 units per month on average, then roof top Solar with net metering is an attractive proposition and investing in the same should deliver you a return on investment of 20% or higher, after accounting for the operations expenses, taxes, duties and infra management fees, that too without any subsidy support.

Besides, you do a lot of good for the environment. Every 20 KW capacity roof top Solar is equivalent to 1400 mature trees in respect of environmental impact. SkyBless is preparing to take this beyond Solar by equipping your premises with electric vehicle charging services, in near future, which can be powered by the same roof top solar plant. That makes it an end to end clean energy use case from generation to consumption @ zero emission.

One sq ft can potentially generate 9 to 11 watts per sq ft. Area required is a function of capacity. E.g. A 20 KWp plant capacity will need 200 sq mtrs or roughly 2000 sq ft of shade free space on your terrace or roof.

Further the energy generation is a function of irradiation, temperature and weather profile of the location, type/ quality/ grade of solar modules, year of operation and maintenance standards adhered.

The modules along with their mounting structure generally weigh less than 60 Kg per mtr square. This is an ordinary load for a RCC structure that has about 2000 sq ft or larger roof top space. Modules are generally placed on the roof floor, water tanks or lift room tops, which do not require any further reinforcement.

The energy generation or yield from the installed capacity depends on:

(a) Amount of sunlight (irradiance) received during the year, temperature, dust levels, shading, air-flow, most of which are linked to the location or city where the system is installed

(b) Type, Grade and Quality of modules, Inverter sizing, quality of design, quality of installation, module cleaning quality and frequency

(c) Tilt and orientation (azimuth) of the modules; and also whether it is a fixed tilt, or variable tilt using single axis / dual axis trackers

(d) Presence of optimization devices used to deal with mis-match loss due to intermittent shading and non-uniform degradation of modules during the plant lifetime.

If the solar modules and associated equipment are of good quality, modules are regularly cleaned, and each module is monitored for its performance then one can achieve optimum generation. All of this is possible only if there is a daily monitoring of the system which also helps to achieve high uptime. The agency undertaking such an activity needs to have the domain knowledge and requisite measurement and monitoring systems. A drop in the yield can reduce or even wipe out all savings and render the investment unviable.

A well designed, rightly installed and fully managed system, of say 20 KW capacity in Mumbai, can deliver in the range of 27,000 to 30,000 units or KWHrs of energy in the first year, depending on the shading profile of the site.

Yes. The drop in yield in the first year is typically about 2.5% of the original rated module power and the yield falls @ 0.8% to 1.5% every year from the second year onwards. Typically, only about 70% to 80% of the original rated capacity is retained by Year 20. This should be factored into the savings calculation, and the ROI analysis.

Degradation can be far worse than the normal range, if modules are of inferior quality or they are installed in shade or not cleaned regularly.

The energy generation is reduced during periods of low sunlight i.e. in early morning, evening, cloudy weather, etc. However, since the Solar Power is grid tied, it does not matter how much power is being delivered by the Solar Plant, as shortfall if any is bridged by the DISCOM supply, the same way it happens every night. So all your utilities continue to function normally as long as the DISCOM supply is available.

During periods of DISCOM outage, a grid tied Solar power system is required to shut down as mandated by the grid islanding guidelines of the regulator. The genset or batteries are required to operate the electrical loads, in an islanded mode, when DISCOM power becomes unavailable . You have the option of operating the Solar Plant even during DISCOM outages by obtaining reference voltage from the batteries or genset, but strictly in an islanded mode only.

Yes. The Solar energy production is primarily based on the amount of sunlight, which changes during the day and with seasons. The purpose of the solar rooftop is not to remove the DISCOM connectivity but to supplement it while reducing overall costs. If the total peak load is higher than the rated solar energy capacity then even on a sunny day when the Solar generation is at its peak, we would need to supplement the shortfall from a DISCOM or back up source. Genset and Energy Storage can technically obviate the need for a DISCOM supply but that will come at a very high cost and effort. DISCOM supply will always be needed.

Batteries are not required in a net metering arrangement. The additional investment in batteries, impacts commercial viability of the project. Battery backup can be an alternative to gensets, provided the peak power demand and energy units required during the longest expected DISCOM power outage can be catered to by the installed battery capacity.

Batteries may be considered and can be integrated with the Solar plant, as a power back up option or to store surplus energy generated by the Solar plant during certain periods of the day for use later in the day, subject to compliance with grid islanding.

Net metering is an option that the DISCOM provides to allow you to send the extra power to the grid in exchange for banked energy credit that you can use when you need it. When your building/home is equipped with a renewable energy source (such as wind or solar power), it can send the excess energy that's generated back into the grid.

As that excess energy is transferred to the grid, your power meter spins backward rather than forward, giving you a credit that you can use to pay for your future energy use. You can roll over excess credit at end of the billing cycle to your next bill, but not beyond the financial year.

If you are a net-exporter to the grid at the end of the financial year, your DISCOM or electricity company pays you for the net-exported units at their average whole sale cost of buying energy, which is less than half of that you save when you bank the energy credit. Net-Export does not earn you any return when you factor the cost of capital and maintenance costs incurred on the Solar Plant.

Net Metering is available in the state of Maharashtra, as also in some other states, and DISCOMs are mandated to provide net metering to aspiring consumers. However this policy may get revised and one needs to check the prevailing policy at the time of planning the Solar or RE project.

The DISCOMs have Renewable Power Purchase Obligation which require them to maximize the power they purchase from renewable generation units. However, whether the consumer can get net metering is subject to the Solar capacity being setup, the sanctioned load, distribution transformer capacity of the DISCOM and such like factors. The electricity regulatory authority in each state in India has published a net or gross metering policy which governs net or gross metering arrangements between DISCOM and Consumers.

The investment for the Society or Building is dependent on the commercial option exercised:

1. Capex Model: Approx. Rs 12 lacs for every 20 KW capacity. Capex per KW falls as capacity increases. Additional CAPEX may be required to make the roof structure suitable for Solar Module mounting and the same shall be over and above the above indicated value.

2. Co-Invest Model: Same as above, except that the building has an option to invest only a portion of the total CAPEX, generally in the structural costs and towards items that are custom designed for the building such as cables, fixtures, etc. The rest of the (movable) infra investments are made by SkyBless. The net returns are shared in the same proportion of the investments after deducting all infra management costs, consideration amount for roof usage, insurance, taxes and duties.

Savings is dependent on (A) capacity, (B) yield or energy generation delivered by the installed capacity, (C) gross unit cost of electricity applicable to the meter to be interconnected with the Solar (or renewable energy) system.

Each of these factors are further dependent on other sub-factors, as stated below:

A. Capacity of the system, feasible for installation depends on:

1 available shade free space 2 sanctioned load on the meter/s to be used for net-metering 3 the consumption on the meter/s

B. The factors impacting energy generation have been discussed in an earlier question in details.

C. The gross cost of electricity consumed by the electrical loads depends on:

1 Consumption slab, Consumer category and DISCOM tariff 2 The levies and surcharges applicable such as wheeling charges, regulatory asset charges

3 Duties and taxes such as electricity duty payable to DISCOM and that applicable for renewable energy for self-use, tax on sale of electricity, GST if any (presently nil).

Net Savings = No of units delivered from Solar x Gross Savable cost per unit, minus sum of (opex + duties + insurance)

Detailed workings over 15/20 years need to be done to estimate savings reliably, once above inputs are available.

Solar Modules are usually rated for 20 to 25 years of operation. It is important to check the manufacturer’s specification sheet. Balance of systems such as inverters, cables, structural elements, may need repairs, replacements or refurbishment at least once during every 6 to 8 years.