Friday, October 23, 2015

Sun shines a light on power

Whether solar power works out economically cheaper or not, the real benefits are to be found in the DIY approach to understanding how you consume power in your home.

The most common questions that I face after we have installed a rooftop solar plant at our apartment are about the government subsidies for green technology or about the savings we make in the bi-monthly electricity bills.
To me, these are redundant and hide the big question that needs to be asked: do you understand electricity better now?
Wait. Let me rephrase that a bit, to make it sound a little less academic:
Am I more aware of how much power I consume in everyday life, the same way a lot of us have become aware about water.
This comparison is apt to the extent that both water and electricity bills take up a huge chunk of our living expenses.
Water is easy to understand. It is tangible and we get to see it stored. We have always rationed it, and wastages are very noticeable.
Electricity, on the other hand, is not tangible to quantify and experience. I think it would be fair to say that, by and large, we have compromised a lot on understanding it. At least, I belong to the generation that depends on an electrician even to change a light bulb.
To me, the biggest takeaway from going solar has been how I have been able to restart my efforts in understanding electricity. That will be my number one reason to go solar.
Let us first address the elephant in the room. No, it is not an economically prudent decision to install rooftop solar at your home — if you are looking at it in terms of “return on investment”. Such fiscal calculations discount the understanding these systems give.
I am a Physics graduate but what I studied in college nearly two decades back was hardly in my memory. So, I quite enjoyed brushing up on some chapters of the ‘Fundamentals of Physics’ by Robert Resnick and David Halliday to just to re-grasp some basics.
There are enough resources online, including videos on YouTube or Wikipedia among others, that can help you get a feel for not just solar power but electricity in general.

Illustration: Mihir Balantrapu
Take a look at this article for example on The website is written for an American audience but has been my go-to website when it comes to DIYs especially (I have become a bit of a coffee snob of late, and keep checking the site for some barista tips, but let us save that for a future post).
Here is the absolute break-down of the essentials of installing a rooftop solar plant. It required setting up an array of photovoltaic cell panels, connecting all the panels to an array junction box, running a DC electrical wiring up to the inverter that was placed in a room, assembling an array of gel batteries to store the power and some substantial civil engineering work.
Although I was aware of the specifications of the components used by our vendor to set up the system, I did not bother myself with the nitty-gritty much.
I was present during the initial site visits that my solar vendor's engineering team made to assess our terrace’s viability to hold a power plant. Having a terrace alone is not a criterion. We needed to know exactly which portions of the terrace did not have a “sun shadow” region and would be ideal for the photovoltaic cells to be placed at.
One of my first learnings was that assessing this space availability was key to determining various important factors, the most important of which was just how big a plant we could put up.
We decided to allocate enough space for an ‘off-grid’ 2-KW plant that would power the lights and fans in a couple of rooms in each of the flats. The decision to go for an ‘off-grid’ plant was made keeping in mind the shared cost of the project by all the apartment-owners. I am unable to go into all the reasoning in this post, but let me just say in an ‘on-grid’ setup, sharing the power load evenly across flats is not feasible. I would still recommend an ‘on-grid’ system whole-heartedly for independent houses.

Solar cells are not necessarily the best option for independent houses, where on-grid systems work better. But for shared electricity, such as in apartment complexes, the off-grid solar cells are a great option. ~ Photo: D. Chakravarty
Once the rooftop plant was installed, the big challenge was to create a scenario where the stored power could be evenly distributed to all the homes in the three-storey apartment complex of ours.
This was where even the smallest of details posed the hardest of challenges. In our case, I can boil that down to a quarter of an inch. The electrician who did the wiring for the apartment apparently decided to save on a few hundreds of rupees by opting for the 3/4-inch pipe, instead of the one-inch pipe, for the concealed wiring.
This became a big headache when we had to run the additional wiring from the inverter/battery room down to the individual apartments to power the rooms we had identified for solar.
There is an important detail to be clarified here. In the case of our apartment, which was constructed as a joint venture between my family and a private builder, the original contract provided for the setting up of a Diesel Generator that would provide power back-up for all the three phases of the entire building in case of a power-cut.
To me, going to the diesel generator back-up ticks all the wrong boxes. I am going to keep the arguments of 'diesel generator vs solar powerplant' out of this post though. But somehow, this option is most preferred by many real estate developers in Chennai. Most apartment builders either run their own franchisee operations in diesel generators or have tied up with other such operators. Why they do not proactively promote solar power is beyond my understanding. The one-shot solution of "fill up on diesel for power-cuts" does not make any sense, be it from an economical or environmental point of view.
Getting back to the challenge at hand: how do we evenly distribute 2KW of solar power to all the homes in a three-storey apartment? We decided to keep the peak production at 1,600 watts and conservatively broke it down to 500 watts per floor. That meant 250 watts per apartment.
So each apartment could have up to three fans and four lights that would run entirely on solar power during the day, when the photo-voltaic cells operate to convert the solar energy into power. These fans and lights would also have battery back-up during non solar-generation hours. That would address the power-cuts we might face during nights.

The Chinnaswamy Stadium in Bangalore became the first cricket venue to go solar earlier this year. The array of 400-KW rooftop solar power panels are designed to produce as much power as 200 All-electric Homes.
Let us not forget that Chennai, like most cities in Tamil Nadu, has had very severe power cuts in recent years, and almost every home has had a tryst with the inverter. We opted for special gel batteries for the solar power, and these came with the promise of longer life. This also led me on a bit of a research on the charge-drain cycles of batteries.
The Bijli Bachao website is a handy online resource on the topic of power savings — solar power in particular. Here is their recently updated article on the cost of photovoltaic cells for solar homes in India. The median costs vary from Rs.30 per watt up to Rs.60 per watt. (We opted for a solar panel that cost nearly Rs.49 per watt.)
Vendors quote anything between Rs.1.2 lakh to Rs.2 lakh per KW for an end-to-end installation plus first-year maintenance of an ‘off-grid’ rooftop solar system. The components whose costs vary dramatically are the photo-voltaic cells and, most critically, the batteries.
We opted for a costly gel-based battery that had a substantially longer ‘charge-drain’ cycle than other batteries and also had a five-year replacement warranty. In the ‘off-grid’ solar system, which runs with a battery back-up, I see no reason to cut corners when it comes to battery costs.
As I kept drilling further into the topic, there were more learnings on how home appliances consume electricity. We could not connect the power lines from the solar plant to “heavy load” devices like high-wattage blenders or ovens. I also found out what the “idle power” was for computers (go ahead, try and Google this for the devices that you put on standby. You would be surprised. This is what I found about my iMac).
Ultimately, everything just boiled down to this. Going solar has helped cut my electricity bills, but it is mainly because I am more aware today. I feel a lot more responsible about using the power we generate in a judicious manner.
The fans we have installed operate at a much lower wattage than most fans of big brands that are available off the shelf. I switch off my Mac when I know that I am not going to be operating for a duration of more than an hour or so.
In order to be truly power-efficient, we picked fans that would operate effectively at much lower power consumption. In fact, I read the power specification labels a lot more closely these days whenever I am out shopping for electrical appliances.
Going forward, whether or not you go solar, this understanding is going to be critical. After all, electricity ain’t gonna get cheaper.

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