This Mumbai couple is setting goals for an eco-friendly urban home

How much power can solar panels typically generate? 

1. Rooftop solar power systems cannot work totally off grid in most urban areas; they must work in tandem with the local electricity provider. The size and nature of the solar system depends on your connected load. In Maharashtra, you can install solar systems with up to 80 to 90 per cent of your connected load. E.g. if connected load is 10 kilo watts (kw) then you can install a system of up to 9kw.
   If your connected load (as per electric bill) is 3kw and you want to install a system of 5kw or 10kw depending on the roof area available, then you need to contact the electricity provider and get the connected load increased.
2. 1kw system is made up of 3 solar panels and each panel is 1 meter wide and 2 meters long. So ideally a 5kw system will need space for 15 solar panels.
3. Claims made by solar installers are that you generate 5 units of electricity per kilo watt per day. Normally it all depends on the amount of sunlight that the system receives and usually the generation is around 4 units per kilo watt. Less generation during monsoon and cloudy days.

What factors must one look out for before the installation?

1. Check with the supplier/installer for government subsidies at the time of buying the panels. Subsidies are only available on panels made by Indian companies. Inverters can be of foreign make.
2. The company that installs the panels will do a ‘shadow analysis’ of your property to suggest the best spot for the panels. The spot and angle (south facing) of the panels will ensure maximum exposure to sunlight.
   

Core installation

1. On grid rooftop solar system is ideal for urban homes. However, if you don’t want to use the roof, then one can raise panels on poles at the floor level too (these are easy to clean but require special permissions). And if the terrace is going to be used, then one has to raise a structure and then place solar panels on them in such a way that you have access to them whenever maintenance and cleaning is required.
   
2. The company that will install the system for you will also be responsible to get all the permissions from your electricity provider.
   
3. Solar panels are connected to an inverter, which converts DC (direct current) into AC (alternate current) and passes it onto the grid of the power company. During the daytime when your usage is maximum, some power is taken from the solar system and some from the grid. In the evening after sunset when the system is resting, surplus power stored in the inverter goes back into the grid.
   
4. The inverter should have an auto shut down system. This is a precautionary measure in case of power outage so that someone working on the electricity lines does not get a shock while doing the repairs.
   
5. The power company will install 2 meters – 1 solar meter and 1 net meter, which will monitor the import and export of electricity. Your solar bill will have two columns – import (for electricity consumed) and export (units that have gone back into the grid) and net units will be the difference of the two.
   
6. You will have to dig a 6ft pit for an earthing wire as a safety measure in case of lightening or sudden power surge etc.

Does the system store unused power?

1. If there are excess units generated by the solar panels that haven’t been consumed, they will go back to the grid and if electricity usage for any month is less than the number of units generated, then the excess units are carried forward to the next month.
   
2. The generation of solar power naturally slows down during the monsoon and one must depend on the grid power for the most part during these months.
3. Electricity generated during daytime by the solar system is used along with grid electricity to run all the home appliances hence reducing your electricity bill. E.g if your consumption is 6kw then 3kw is drawn from the rooftop solar system and 3kw from the grid.
4. Please note that the panels do not cover water heating. That requires a separate installation.

1. Rooftop solar panels get dirty with bird droppings and dust from the air. All you need is a water hose and a squeegee or microfiber cloth to clean the panels. Cleaning must be done either before 8am or after 6pm when panels are not so hot.
2. Do not clean solar panels in the noon as water can damage the panels as they are hot.
3. The solar installing company also provides an app which monitors the number of units generated every day. E.g if the daily generation is 25 units and for a few days it shows 22-18 units or so, then it’s time for a clean-up
4. Do not walk over the panels even though they are made of toughened glass. Walking on the panel can crack the glass and affect proper working of the panels. Although while cleaning if need be, walk on the edges of the panels made of aluminium.

1. The 250 LPD solar water heater system by UtsEco International has an inlet for water to enter and get into glass tubes. These tubes heat the water which gets stored into a tank by thermo siphon system. From the outlet, a special pipe (not the PVC pipes) goes to all the bathrooms and the kitchen, ensuring piping hot water 24/7 during 9 months of the year. 
2. Remember, the outlet pipe of hot water should be installed into the inlet of your existing water heater so that hot water passes through this into all the taps. During the monsoons, you simply need to switch on the water heater without making a separate connection for it.
3. This does not work during the rains and one needs to switch to the water heater during 3-4 months a year. 
4. Water stays hot in the solar water heater for approximately 24 hours.

Solar water heater is made of ETC tubes that efficiently trap the heat. One only needs to clean the dust accumulating on the tubes from the outside. This can be easily be removed by spraying water with a pipe or with a cloth, if needed.

How do you start?

1. There are many ways to install a rainwater harvesting system – recharge of a borewell, digging a recharge pit, storing water running off from rooftop in tanks etc.
2. It’s best to have your place studied by an expert company before you settle on the type best suited for your home/building.

In case of directing rainwater to an existing borewell

1. If you use an existing borewell, a pipe carries water from the terrace into a little well made with cement rings. This well has a filter placed inside with sand, gravel etc that purifies the water before letting it into the borewell. The rings ensure that only purified water enters the borewell.

2. Ensure that you clean the terrace before the rains or just let the first couple of showers wash out the dirt before letting the water into the borewell. There’s a valve you can add to control the water that enters the borewell.

1. The filter needs to be cleaned professionaly twice a year – once before and once after the rains. This costs about  Rs 2,000 each time

1. There are multiple options for home composters in the market. See what suits your home depending on the space available. If you live in a flat, you can go for smaller bins that occupy less space or can be kept on the grill. 
2. In case of vermicompost like the one installed in the Bajaria house, buy a compost bin, lace the bottom with a mix of coconut husk, cow dung and coco peat, an organic accelerator to the process (easily available at any nursery). Add to this the friendly worms or microbes bought from a supplier or a nursery. You can also check with the local municipal body such as the BMC that is expected to support citizen initiatives for cleaner living. 
3. Next, start putting your wet waste and stir occasionally.

1. One needs to maintain basic hygiene around the bin and ensure that the contents are regularly stirred. 
2. Ensure that the bin is well aerated.