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Solar PV – Commercial How to determine the ideal size of my solar power plant?

3 key parameters decide the ideal size of a solar power plant for a particular application.

  • The objective of reduction of power costs by a certain percentage or obtaining an uninterrupted power source.
  • The budget on hand.
  • The physical space available at the premises.
Do I need a battery if I have only day time power requirements?

As long as a larger generator back-up is available commercial applications can be best run with grid connected systems without batteries. Day time power generated from solar power can be used for loads and any excess generation exported back to the grid to be adjusted in monthly power bills with a net metering connection. Also the plant can work in sync with a diesel generator of twice the capacity to reduce diesel consumption with solar power at the time of power outages.

What is the ideal solution for loads running both during day or night?

Grid connected battery-less systems or a HYBRID system that can provide essential back up for night time loads while also giving benefits of grid export during the day can be used for commercial establishments that have loads during day and night. The quantum of back up can be determined based on the loads to be powered.

What could be the commercial benefits of solar power?

Very low payback time and low levelised cost of power are the main advantages of Solar power. The total cost of the solar plant, less any benefits adjusted for depreciation and tax and added on with future costs like maintenance will give the life time cost of the plant. The life time cost divided by the net discounted generation for 25 years is the levelised cost which comes to around 2.5 to 4 Rs. per unit. When compared to increasing tariffs that have already crossed 10 rupees a unit and diesel power that costs over 25 rupees a unit Solar Power has come out a reliable and viable alternative. Solar power plants have accelerated depreciation benefits as per Section 32 of the income tax act which provides for 80 % of the capital investment to be claimed in the first year if the installation is done before September in the particular financial year and in two years if installed after September. Commercial plants provide energy security by locking in the power costs of a facility for the foreseeable future.

How to reduce diesel generator costs by opting for a solar power plant?

Two options are there to reduce diesel costs with a solar power plant.

  • To have a HYBRID grid connected power plant that gives back up for key loads during power cuts thereby reducing the necessity of switching on a DG set.
  • To use DG synchronized inverters that can share loads with the DG, thereby improving efficiency and reducing diesel consumption.
Where should I locate the solar power plant?

Rooftop which is shade free and accessible is an ideal place to locate the solar power plant. A flat roof, a pitched roof, a truss roof or shingles can be used. Solar plant can also act as a pseudo roof for the building.

How much area is required for a solar power plant?

An area of 80 to 100 square feet per kilowatt peak of solar panel array is required for the Solar power plant.

What are the maintenance costs on a solar power plant? Are AMC services available?

The main maintenance costs are related to cleaning of the Solar plant. Training can be provided to the facility staff at the premises. AMC services are also offered by our professional engineers at competitive rates.

Can solar power be used to run air-conditioners or heavy equipment?

For air conditioners or heavy equipment, Grid connected solar power plants can be used which are run in synchronization with the local power grid thereby shifting loads on to the main line. Here any loads can be run whereas with a HYBRID power plant, the inverter can be sized to accommodate any load be it air-conditioners or heavy equipment.

Solar PV – Residential How much solar power is needed to run a house?

This differs from house to house depending upon the power profile and load use of each customer. The ideal solar power plant capacity needed is determined by the final objective of the customer like a certain percentage of reduction in the power bill, availing uninterrupted power or having a power source independent of grid and also on the budget in mind. A 2 KWp power plant can generally power basic loads like lights, fans, a television as well as a washing machine, a 3 KWp plant can supply power to a refrigerator and a mixer, a 5 KWp plant can run an inverter type 1 Tonner air-conditioner in additional to the above loads.

How to find out the right size of solar power plant needed?

The total units of power needed each day can be calculated by no of watts of each item multiplied by the hours it may be used and totaling the kwh of these loads. Divide the total kwh required each day by 3 to get the ballpark size of the Solar power plant. However, solar engineers of TeamSustain are ever ready to assist you with the right system sizing if provided with a detailed load profile.

Can a refrigerator, motor pump or air-conditioner be powered by Solar power?

As long as the solar power plant is equipped with ample capacity of PV and the right inverter for the application it can run any load. In fact it is easier to accommodate loads like refrigerator, washing machine, mixer etc. in smaller residential power plants. Air conditioners Inverter type, are best to use with solar power and a small AC can be accommodated in even a 4 KWp power plant. Higher capacity inverters are needed for Motor pumps unless they are DC as they come with a huge surge. Our Swiss inverter range can accomplish a grid sharing function to move surge currents on the mains supply as long as the grid is available. As such our clients use diverse capacities of power plants that power multiple air conditioners and other power loads.

What happens to solar power during monsoon or rain?

Solar power can be generated as long as sunlight even in diffused form is available. This is possible as photovoltaics work on light rather than heat and thus never cease to function or generate power. During heavy monsoon when sunlight is at its minimum probably 20-25 days at the most there could be a few days of very low generation. However high quality solar panels exhibit a lower loss of power compared to cheaper solar panels. Moreover, it is possible to size a solar power plant and its battery bank to work through such days too especially if it’s a remote application with limited access to grid power.

What area is needed for a residential solar power plant?

The area needed for a solar power plant is 100 square feet per kilowatt peak of panels approximately. Depending upon the area of installation namely a flat terrace, an inclined pitch roof, a truss roof or so on this can vary upwards or downwards.

How much maintenance is essential and what does it cost?

Residential plants need very little maintenance. Regular cleaning with a wet mop at least once a fortnight is needed for a plant in the city exposed to dust whereas plants installed away from dust could be cleaned once a month. The annual degeneration of the Solar plant can be kept at the lowest possible with regular cleaning of panels. Bird droppings or leaves that obstruct the solar panels should also be cleared. If the batteries are flooded they need to be topped up once every three months. If the electrolyte level subsides the terminals should be cleaned with Petroleum Jelly for a VRLA gel battery bank. It is vital to get a good MPPT charger that can automatically perform equalization charging once in 15 days or 30 days and to have a qualified service engineer check the condition of the plant once in 6 months.

Which is the right location to install my solar power plant?

A shade free area is preferable to install the solar panels facing the south direction at an ideal angle of inclination recommended by the engineer. Easy access to the plant should be ensured for cleaning. If panels are located on an inclined roof it is preferable to install a walkway or ladder to access the panels for cleaning. The inverter area too needs to be at an easily accessible place & the collection of inverters and the controllers along with the battery bank are to be installed no more than 10 metres from the panel enclosed in a climate protected area free from dust, moisture, rodents and water leakages.

Is it possible to sell unused power back to the grid?

At many places in India Grid export is now available subject to state policy. Two options are there.

  • Battery less grid connected system where energy generated during day hours is either consumed by loads or exported back to the grid for net metering benefits. But, during power cuts, the inverter will shut down for anti -islanding protection. At such times, the inverter can work in sync with a diesel generator of twice or more capacity, but it is rare for residences to have generators and secondly it doesn’t reduce diesel consumption beyond a certain limit.
  • A HYBRID battery based grid connected system which will go in to standalone mode and stop export during power cuts, but also provide power to the loads. The nominal battery can provide back up during power cuts at night to the extent designed.
Is a battery less system feasible for my residence?

Yes as long as there are sufficient back up arrangements in place for power cut hours it is possible to use a regular grid tie plant.

In a solar power plant what is the life span of a battery bank?

A battery bank life span is measured in cycles of discharge rather than in years. A good battery bank set at 80 % depth of discharge will give a life of 1200 cycles or roughly 3.5 years whereas a battery bank set to 50 % depth of discharge will give a life of 2000 cycles or roughly 5 years. An ample battery bank that can provide regular loads at 50 % DOD is essential to maintain longer life. To improve the life of the battery bank adding autonomy or sizing can be done. A grid connected HYBRID plant’s battery on the other hand can even run for 8 to 9 years. Lithium ion and Vanadium redox are newer technologies which can offer lives of 10 to 20 years.

What is the approximate replacement cost for batteries?

It can vary from 8 % to 30 % of the plant cost depending on the size of the battery bank.

What determines the life of a solar power plant?

The maintenance and usage pattern of the individual power plant are the factors determining the life of a solar power plant. Solar panels generally have a derating warranty of 25 years whereas top European inverters have a life extent between 15-20 years depending on the external climate.

How do I get service support?

TeamSustain provides 24 X 7 service support to our clients. Our engineer can visit the site in 24-48 hours and provide the service required at our standard rates.

What should I do if my solar power plant fails?

We always install a manual bypass switch for the solar power plant that is located at a convenient point. This switch can be used to get power from the mains grid till a TeamSustain engineer visits the site to restore the solar power.

What is the payback on a solar power plant?

The payback can be as short as 3 years or up to 6 years depending upon the power tariff, the number of loads shifted to solar power and the total load use from grid and diesel generator.