So­lar En­ergy for Cold Stor­age: Util­is­ing grids to re­duce cost

util­is­ing grids to re­duce cost

Cargo Talk - - Contents -

Why do stand-alone SME in­dus­trial units, homes, and I in­clude cold stor­ages, shy away from in­stalling so­lar pan­els to gen­er­ate elec­tric­ity? Yes, cost is a fac­tor as al­ways. But that is one fac­tor that is con­tin­u­ally show­ing a down­wards trend. The other rea­son quoted is the has­sle of op­er­a­tion and main­te­nance.

To­day, if re­ports are true, the sell­ing price per watt of so­lar photo voltaic is about 0.5 USD. Re­ports also sug­gest that this price is ex­pected to come down to 36 cents per watt in five years. Past records show that, in 1977 the price stood at US$ 76 per watt. How­ever, it can be re­duced dras­ti­cally by im­ple­ment­ing a sci­en­tific method of us­ing so­lar en­ergy for cold stor­age.

Peo­ple of­ten wor­ried about the has­sles of op­er­a­tions and main­te­nance. This is typ­i­cally be­cause the im­plied con­cept of So­lar PV panel re­quires the use of a `bank’ of bat­ter­ies to store the cheap elec­tric­ity. And bat­ter­ies need to be re­placed ev­ery now and then. The elec­tric­ity that is gen­er­ated from so­lar in­so­la­tion would need to be stored in bat­ter­ies, which in turn would be sourced to cre­ate AC power for use in com­mon util­i­ties. Another lim­i­ta­tion for in­dus­tries is that they may need tri-phase in­put into their ma­chines.

But why store this elec­tric­ity, why bother with bat­ter­ies and et al? What if the so­lar power is fed di­rectly into the lo­cal grid? I am not talk­ing about shar­ing the sur­plus gen­er­ated with the grid… the con­cept is to feed ALL that the sun gen­er­ates for you, straight into the grid.

What one uses off the grid, one pays for as usual. But what your pan­els feed into the same grid, earns you the same rate per kWh. This means you keep both cir­cuits in­de­pen­dent of the other, the grid be­ing the main back­bone.

Sure, such a mech­a­nism does not serve the pur­pose of con­ti­nu­ity of power or as an off- grid re­serve sys­tem – there are no bat­ter­ies.

No bat­ter­ies mean none of that ini­tial cost, no re­cur­ring cost for re­plac­ing them, no wor­ries of main­tain­ing a sep­a­rate ven­ti­lated room, com­pli­ance con­cerns, etc. In fact, in all like­li­hood, the sole main­te­nance cost would be that in­curred for an odd clean- up of the so­lar pan­els sur­faces.

The other ad­van­tage is that a me­ter mea­sures what you out­put off your panel in­stal­la­tion, and you get paid for the elec­tric­ity gen­er­ated. For ex­am­ple, if you con­sumed 20kWh in a day, and fed 10kWh into the grid, you end up pay­ing for only half the power you con­sumed.

I came across this con­cept and though it would be a great idea for our cold stores, most of which are in ru­ral or semi-ur­ban ar­eas. Most com­plain of the high cost of en­ergy which bite into their op­er­at­ing mar­gins.

What if each cold store was em­pow­ered to in­stall so­lar PV pan­els, say with an av­er­age 100,000 watt out­put. Go­ing as per peak power loads in such a fa­cil­ity, 100 kilo­watts gen­er­ated ev­ery hour would help a cold store’s needs, but imag­ine the num­ber of bat­ter­ies that would need to be main­tained. Yet this 100kw when fed into the grid, could help power the equiv­a­lent of one thou­sand street lights of 100 watts each.

We have about 6,000 cold stores in the coun­try, and if we had 30% of them feed­ing the grid at 100kw each, it would mean the grid gets 200 MW of green elec­tric­ity dur­ing sun­light hours. The pan­els would ad­di­tion­ally re­flect the so­lar in­ci­dence on the cold store roofs, re­duc­ing heat load in turn re­duc­ing the re­frig­er­a­tion load.

What do you say, can this be done? Should this be done? Will the ex­perts ad­vise if this will make sense?

It may be per­ti­nent to men­tion that 100kw of so­lar pan­els would cost about Rs. 32 lakhs, drop­ping 25% in com­ing years. Elec­tric­ity charges per 100 kW is Rs. 5,500 per day if used 8 hours ev­ery day, and is ex­pected to go up 15% in next 5 years.

Pawanxh Kohli Chief ad­vi­sor


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