Solar Lighting a Dark Stairwell

How much does it take to set up a solar-powered system?

I've been mulling over the installation of a solar-based back-up for a while now. For starters, I wanted to install a self-contained system that automatically lights up our building stairwell. 

The problem is quite straightforward: We stay in an apartment complex that has about 30 towers (4x4 houses each), without a central power back-up. Each apartment has a stairwell that is vulnerable to power outages. At night - especially in winters - it becomes particularly difficult for the children and the elderly to use the staircases.

From whatever little I have gathered so far from the net, a solar-panel based lighting system would require: solar panels, a charge Controller, a deep discharge battery, wiring (4mm), a light-activated switch, and a panel of LED lights.

What I do not know for sure - and this is an ongoing challenge -  are questions for which I am yet to find dependable advise:

• How do I align the panels on the terrace so that they can be installed - and maintained -  easily?
• The most appropriate configuration of panel + controller + battery + LED panels?
• Which is a reliable place from where I can buy the components?

At least in NCR Delhi, it is difficult to find somebody who can guide you. The shopkeepers and aggregators always want to sell you the biggest system possible, whether you need it or not. They are all chasing contracts from big-ticket clients - the railways, public-sector companies, large housing complexes to keep the assembly lines running. Companies like Simpa Networks are building models that resemble telecom service providers. Not for them the one-time pocket-change from individual residences.

Reliability is also an issue. Almost none of the components comes with a performance guarantee. The usual refrain is "electronic cheez hai, kuch bhi ho sakta hai..." (its electronic stuff - anything can go wrong!). Not an encouraging start for people who see this as a long-term investment in clean energy.

Amongst all the people I have met, the most sensible advise came from a marketing executive at Maharshi Vedic Construction. His point was simple - longevity of any equipment depends on how you go about maintaining it. He gave the example of an inverter he has installed at home 17 years ago. According to him, regular vacuum cleaning and greasing is all it takes to make electrical equipment last longer. Clearly he had a point.

Yet, even as a manufacturer of solar panels and controllers, he could not offer a formal performance guarantee for the stuff he was selling. His panels cost INR40/Wa, so a 60Wa panel cost INR2400. The controllers were available only for 10A and 20A with a starting price of INR1100 (note: the 10A model came with a useful USB charging port).

Ultimately, I ended up buying the following stuff from the electonics wholesale market at Bhagirathi Palace, Old Delhi:

- Solar Panel Tata BP - 60Wa (INR 1200)

- Charge Controller - (INR 250)

- LED lights set - 12W (INR 150)

- Twilight Switch - 12V, 6A (INR 368) - from Electrocine Corp, 1801/5-6, Bhagirath Palace

- Copper wire (INR 160 for 10m - Kalinga Gold 4mm copper wire) 

- Battery - 26Ah, 12V

I was about to purchase a new 28Ah battery when a friend offered to pass on an old battery he was going to dump anyway. It has been purchased a year ago but seemed to have got completely discharged due to non-use. It took three about three days for the voltage to climb over 12V.

Apart from the battery glitch, the system seems to be working beautifully. 

Now, only a few questions remain: The battery runs out of juice in just four hours...is the LED panel drawing out more power than 12W? Or is it just an old, deep-discharged SMF battery acting up? How does one measure the W/h remaining in a battery unit?

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Vendor's Contacts:

* DC Twilight Switch - Electrocine Sales Corp, 1801/5-6 Electrical Market, Bhagirati Palace - www.escorp.in 

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LINKS & REFERENCES

* Bijli Bachao - solar panels in India - https://www.bijlibachao.com/solar/solar-panel-cell-cost-price-list-in-india.html

* Understanding Solar Power - an excellent resource that brings "Solar Power to Ordinary People"-- https://livingonsolarpower.wordpress.com/  

* Instructables - Solar charges with day-night switch - http://www.instructables.com/id/Solar-charger-with-day-night-switch-v2/

- 2N3904 NPN Transistor, linked to photo transistor and then using a 100k pot to regulate the sensitivity level.
- Day-night switch - http://www.ebay.in/itm/222242083233?aff_source=Sok-Goog
- INR 292 on EBay

- Solar charge controllers - https://www.batterystuff.com/solar-chargers/charge-controllers/

Solar Powered Vendors

The world is moving on -  coconut vendors are now equipped with solar panels!

Until last year the most popular - and affordable - lighting technology available to the vendors was the "petromax" lamp. Messy, polluting and hard to maintain, these kerosene powered lamps also thrived on a blackmarket for fuel siphoned from the public distribution system. 

Most of the kerosene lamps have now been replaced by LED panels.   A supply chain had evolved around this model in which entrepreneurs had started supplying a complete LED lighting set (light panel + battery + stand), to the street vendors for about ₹20 a night. After 10:00 PM they would go around collecting the lamps, and then getting all the batteries recharged again from an AC outlet.

Now vendors - especially those on the open roads - have progressed to next logical step: charging the batteries using solar panels. 

In this case, the vendor, Kasim, set himself a budget of ₹ 3000 and got a 40Wp panel, a refurbished 12V battery of unknown Ah rating and two LED panels.  He has also paid extra for a charger-box with a 2-pin plug. He got conned on three counts - the seller sold him mobile charger calling it an "inverter", the LED panel cost him ₹200 (available at ₹80), and the worst of all - nobody told him that he needs a Solar Charge Controller (SCC).

Since the SCC controls the fluctuating voltage coming in from the panels, and optimises the charge that a battery can take, Kasim's entire investment s likely to go kaput in a few weeks. 

Kasim's case illustrates the problems most of face while adopting a new technology. He is, of course, an early starter. While most of the other vendors prefer a battery-rental model (₹300/week), he must have worked out that an investment in panels would spare him rental expenses within two months. 

I have tried to help out at bit by checking at Lajpat Rai Market (Old Delhi), and telling him that SCC's are available at ₹ 350 (Shop no. 40, 6Amp, DeepSolar brand). Will he get one installed before it is too late? Or will he continue with his "jugaad" setup, get disillutioned with his panel set and return to the regular mode?

And then, even if he does get himself a SCC, it would be yet another component which comes with no quality assurance, standard ratings or guarantees. 

We have set ourselves ambitous targets for increase in renewable energy capacity. The focus so far seems to be on big companies and on turning vast areas into solar-energy farms. While this is necessary, it is also important to ensure that entrepreners like Kasim have access, not only to solar equipment of reliable quality, but also to information and guidance that helps avoid unnecessary loss of faith in a good source for off-grid, renewable sources of power.

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LINKS & REFERENCES

* https://en.wikipedia.org/wiki/Charge_controller

* Charge Controllers - http://www.freesunpower.com/chargecontrollers.php

* Do I need a Charge Controller? -- http://forum.solar-electric.com/discussion/4518/do-i-need-a-charge-controller

- Battery AH * 2% * Vmp = Panel Wattage

* Do I need a controller? - http://www.mrsolar.com/content/faqs/when-do-I-need-a-charge-controller-and-why.html

* Solar Panel Selection Guide - https://www.bijlibachao.com/solar/india-solar-photovoltaic-pv-panels-selection-guide-understanding-system-quality.html

* MNRE Achievements - http://mnre.gov.in/file-manager/UserFiles/Achievements-of-Power-Coal-and-MNRE-Nov2015-English.pdf