Every time when we talking about development of Solar Energy in Armenia, many people are interested: “Is it possible to cover all of Country energy demand by using only the energy of the Sun?”
The question is, of course difficult, science and technology, economics and politics are mixed here. To honestly and definitely answer this question, it is necessary that the above factors will be coincide.
However, let’s see what happens when these factors completely coincide on specific islands in the Pacific Ocean. We are talking about the islands of Tokelau (New Zealand). Being very close to the equator at a latitude of 8°, three small islands ( Fakaofo, Nukunonu, Atafu ) with a total area of only 10 sq. km. and a population of about 1500, realized the dream of many of us, having switched to 100% Solar Energy. The project was implemented by Australian Company Powersmart Solarin 2012 and required 5 months and 8.5 million dollars of capital investment 7 million of which has been invested by New Zealand Government.
The whole system consists of 4032 solar modules (230W of each) of total power 930 KW, 196 string-inverters, 84 off-grid inverters, 112 charger controllers and 1344 rechargeable lead-acid batteries with a total capacity of 8064 KWh.
The basis of entire system is the so-called cluster consisting of 144 panels and 7 string-inverters, 4 charge controllers 3 battery inverters and 48 batteries with a capacity of 288 kWh.
Figure bellow, shows the basic design of a single cluster.
The panels in the array convert sunlight into DC electricity, which must be converted to 230 V, 50 Hz AC electricity to be injected into the utility grid, or 48 V DC electricity to be stored in the batteries.
String inverters: The string inverters convert the panels’ DC electricity into usable 230V, 50Hz AC electricity that is powered into the grid./
DC charge controllers: These devices convert the panels’ DC electricity into 48V DC electricity that is used to recharge the batteries.
Battery inverters: The battery inverters are at the heart of the cluster design. They:
- form the grid by setting its voltage and frequency;
- regulate the batteries state of charge;
- throttle back the solar production from the DC charge controllers and the string inverters if the batteries are full and loads on the grid are low;
- activate the backup generator when the battery state of charge is below a certain threshold;
- convert the energy stored in the batteries to electrical energy used on the grid (e.g. at night or on cloudy days when solar production is below the load requirements of the grid);
- convert any excess electricity from the string inverters into 48V DC electricity to charge the batteries.
Batteries: The batteries are used to store any excess electricity produced by the solar panels and not used by the loads during the day. This energy is used to power loads at night or during periods of very low irradiance when the solar production cannot meet the loads (e.g. cloudy days, dawn and dusk). The batteries are sized to be capable of providing power for several days in a row.
Multicluster Box: The Multicluster Box (MC- Box) combines all the clusters into a single system. Whereas the battery inverters are at the heart of the cluster, the MC-Box is at the heart of the PV system. The entire system is controlled by a single master battery inverter, which communicates to the other inverters to coordinate power delivery via the MC-Box.
Backup generator: Backup generator: The generator is called upon to deliver power when the battery state of charge is below a given threshold and the PV modules cannot provide sufficient power to recharge them. The generator is typically sized to provide the entirety of the loads on the grid, in case of a malfunction of the PV system or for maintenance of the battery inverters. The dispatching strategy for the generator is such that it is either run at its optimum load factor, or not run at all.
This improves the fuel efficiency of the generator, and reduces maintenance costs as maintenance is done on the number of hours a generator is run, regardless of the amount of electricity produced.
Previously, the annual energy consumption for all three islands and the necessary peak capacities were studied. As expected, peak capacities were at 8 am and 8 pm, which completely in line with the lifestyle of any rural area where there is no industrial manufacturing.
Of course Armenia is not the islands of Tokelau, we are not on the equator and energy consumption is much more higher. On Tokelau, for example, there is no need to heat the homes and there are no air-conditioners at all, and the population is engaged only in fishing and agriculture. But this example shows that principally the switch on to 100% or almost on to 100% solar energy is not technically impossible issue. At the same time, we should not forget that in contrast to Tokelau in Armenia there is still a sufficient resource of hydroelectric power stations.
On the other hand, even in Armenia, we have a lot of rural places, where the lifestyle completely the same as in Tokelau. Keeping in mind, that the prices on solar power plants installation were dropped almost on 75% since 2012, and the technologies have been sufficiently improved, construction of such a Solar Power Plant in Armenia will be much more cheaper and effective. We already have an experience in design and construction of several stand alone solar power systems, and why not, we can completely implement such a project in Armenia. The beauty of such stations is that they are completely independent of the network and can give electricity to the consumer in the absence of it.
As for Tokelau, before the switch on 100% solar power, they spent 1 million dollars every year on fuel and transportation, and as we can see, the cost of solar station will be completely compensated in two years.
Very impressive, isn’t it ?