Dear Suman,

I think it is not an option to simply use a battery or battery-pack big enough to do the trick as this would turn out to be very expensive.

Talking about months or years means at least 10.000 operating hours and even if your devices consume 1W only, this leads to 10 kWh storage plus battery management.

I'd suggest to use a battery good enough to power the devices for 100 hours or even less, supporting them using a small solar cell.

If battery voltage and solar cell voltage match, no complex charger is needed.

Proper power management will help to reduce power consumption, so consider disabling any functionality you do not use, especially wireless communication like Bluetooth or WLAN.

In case you can access other local power sources like small wind generator or even a small watercourse, things would get more complex - and more expensive - but may also contribute to standalone operation with no grid to connect to.

Dear Suman,

I think it is not an option to simply use a battery or battery-pack big enough to do the trick as this would turn out to be very expensive.

Talking about months or years means at least 10.000 operating hours and even if your devices consume 1W only, this leads to 10 kWh storage plus battery management.

I'd suggest to use a battery good enough to power the devices for 100 hours or even less, supporting them using a small solar cell.

If battery voltage and solar cell voltage match, no complex charger is needed.

Proper power management will help to reduce power consumption, so consider disabling any functionality you do not use, especially wireless communication like Bluetooth or WLAN.

In case you can access other local power sources like small wind generator or even a small watercourse, things would get more complex - and more expensive - but may also contribute to standalone operation with no grid to connect to.

Best practise could be to adopt your program first to avoid power consuming functions ( close non-essential connectivity  blocks, GPIO pins, reduce internal clock, take advantage of temporary standby or sleep mode, wakeup by watchdogs or interrupts and so on) and then measure your power consumption over a period of time.

After that you can choose your appropriate method / device for power supply.

As Martin said before, a solar panel is an elegant solution.

Dear Marc,

I'm curious...

You consider London or Leicester a region that correlates to the question in regards of "...remote location without power supply"`?

;-)

Solar cells would do the job. But if the device is carefully designed to avoid any leakage currents during stand by mode, this would also save power drawn from battery.

Do any body have idea how and how well solar cells work.

I mean are they connected to a battery which is getting charged by solar cell regularly or it is connected directly to the device to be powered.

I also want to know how much volts a solar cell can generate and what time it take to charge a battery because I heard it is a slow process.

Dear Suman,

you can consider this a question of configuration and money spend.

A single solar cell will get you a few volts only. Paralleling will increase the current delivered, series-connection will increase the output voltage.

If you have a certain battery and you add a well-tuned solar panel, the cell can be connected to the battery directly without charger, maybe just adding a diode to reduce leakage at low solar radiation.

In case your battery is something like a single lithium-ion block of 3.2V, 200Ah it will be good enough to power 10W for 60 hours. Well - it may be a little expensive though :-)

To refill the battery within 8 hours  - 14 hours energy has been drained - 140Wh would be needed. Throwing in some margin  you might plan on 280Wh to be on the save side..

A solar panel providing 4V can be connected to this single battery without charger, having a single battery means you won't need a battery management system. With 4V and 8 hours time, the solar panel would need to provide little less than 9A to do the trick..

Dear Suman,

Your question is unclear. All depends on your particular situation. Do not forget that a common low power microcontroller consume under 1 microampere in the sleep mode. The most of the WSN instruments have months/years autonomy. But, the wireless sensors sleep most of the time and wakeup periodical (timer interrupt) or asynchronous by the external interrupt. If your situation accepts that behavior you can use every test boards delivered by semiconductor or wireless module manufactures.

All of the above suggestions are valuable.In addition please see if the following is feasible as out of the box wild suggestions.

1.Depending on total energy consumption/ power not often used Energy harvesting

such as ambient heat, sound , vibration , ambient light etc.(in the old days there was an automatic watch which worked on general human hand movements). Also it is reported that heat pipes sunk in the ground uses temperature differences in a few meters of the ground depth is used to melt winter ice , so this could be a possible energy source.

2 Another exotic solution(depends again on ratings being considered I suppose)would be to use passive network which receives power from the base station.

 Cheers

Very interesting and original ideas, Narasim! I like this manner of thinking...

Thanks Cyril for your kind remarks . There is a further thought on this which might be more practicable and with possible business prospects.viz

1. Reduce the power consumption using perhaps ASICs

2. Store mechanical energy  in micro flywheels at high speeds in

perfect vacuum sealed units(possibly magnetic bearings)  something along the

line of "system on chip" . This would meet the Green requirement as well

and perhaps replace chemical batteries.

Cheers

Narsim

Oooh, the last suggestion is beyond the ordinary human imagination...

Use a solar panel or a small wind turbine to keep battery charged.

Use solar panel to charge the battery. use battery voltage for power converters onboard that will do the job.