Solar Energy in Jamaica
Sooner the better….
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Jamaica has immense renewable energy potential, but imported fossil fuels like coal, oil, and petroleum products primarily fulfill its energy needs. These imports negatively influence the country’s foreign exchange reserves, gross domestic product (GDP), and electricity costs. Therefore, the Jamaican Government has implemented the National Energy Policy (NEP) 2009-2030 , which aims to diversify the island’s energy needs through renewable energy generation. The renewable energy share in the total energy mix of Jamaica is just above 10%, despite immense solar energy potential. In NEP 2009-2030, the Government aims to increase renewable energy by more than 20% by giving various incentives and tax rebates to domestic and business consumers investing in renewable energy systems. The Government has also announced the exemption of custom duties and tax charges on the residential solar energy systems Tax incentives – Jamaica. The petroleum corporation of Jamaica Petrojam Limited , states that solar energy as an alternative to petroleum-generated electricity will help ensure energy security while raising the country’s energy efficiency. Long-term loans up to JMD 1.2 million are also available for residential solar and solar-thermal projects PV Loan Policy.
Power generated per square meter (W/m2) defines the solar panel capacity. The maximum solar irradiation falling on a solar panel is around 1000W/m2, which lasts only a few hours a day. Solar energy is utilized during full sunshine hours. Usually, 4-6 hours per day is a good number for solar harvesting, and it is also true for most parts of Jamaica Solar Hours in Jamaica. The Jamaican southern coastal areas have tremendous solar energy potential. The solar irradiation map shows that the southern coastal areas, including Kingston, Spanish Town, Black River, and Savanna-la-Mar, are ideal for utility-scale PV plants Jamaica PV Potential. Even the Jamaican cloudy and highland places like Port Antonio are blessed with 1460 kWh per annum from just a 1kW solar array. However, abundant sunshine in any part of Jamaica ensures the feasibility of solar energy installation for residential and commercial sectors. A typical household consumes 10,000 kWh per annum of electricity. Dividing the annual consumption by the average solar energy potential of 1460 kWh per annum gives the power rating of the PV array needed to generate electricity for a house (10000/1460 = 7 kW). The 7kW solar array can easily fit on a house rooftop.
Technological advancements in solar energy continuously reduce costs while increasing reliability with the noise-free operation. Unlike other renewable systems, the solar energy system benefits houses, businesses, corporations, and even industrial customers equally. However, basic technical details like solar module types, battery, and inverter sizing are perplexing for many people, which delays their decision to go solar and thus prevents substantial monetary gains.
Solar Energy Harvesting
The basic building block of PV technology is a PV cell that generates low DC voltages when exposed to light. Then, many PV cells are combined to make a PV panel, and panels are combined to form PV strings with higher DC voltages. Finally, the output voltage of the string is converted into usable electricity via power electronic devices like charge controllers, converters (DC-DC), or inverters (DC-AC).
The figure shows a modern home equipped with a solar PV system. In this example, the solar string’s DC power is converted to power up the user equipment and sold to the grid.
Types of photovoltaic (PV) systems
There are many types and configurations of PV systems. The three principal classifications are:
- Standalone PV
- Grid-connected (GC) PV
- Hybrid PV
The specific type is selected based on the application. For example, for a remote village or island standalone PV system is a suitable topology. Similarly, for a busy metropolitan, rooftop grid-connected PV installation will help cut electricity bills. Photovoltaic power systems are generally differentiated based on their operation and connection to other sources like batteries or utility grids.
Standalone PV systems
The simplest PV systems involve connecting the Solar panels or arrays directly to the DC load (such as DC lights, fans, motor pumps, or batteries). A typical standalone PV system uses solar energy to power a load (DC or AC) and store the excess solar energy in battery storage. The battery storage can be utilized later during low irradiation or night. This PV system is flexible enough to power both DC loads and AC loads.
Grid-connected PV systems
In grid-connected (GC) mode, the DC power is converted to AC power and integrated into the national power grid. In GC mode, a residential or business customer can generate electricity and sell it back to the utility grid. When the consumers sell electricity back to the grid, it is called net metering. Net metering offsets the cost of electrical energy used by the homeowner or business.
Hybrid PV systems
Hybrid PV combines solar panels with other energy sources to generate electricity. The other sources may be a chemical, fuel cell, wind generator, or petroleum-based generation. During rainy or cloudy days, the intelligent hybrid system utilizes alternate energy sources instead of solar panels to fulfill the electricity for the load. Generally, PV is combined with chemical batteries to form a hybrid standalone or off-grid power generation unit.
Components of PV system
The following Figure shows the essential components of the solar energy system. Solar panels are generally 20 to 23% efficient. A typical solar panel produces around 250W- 500W when fully illuminated in sun rays. Many solar panels are combined to attain the required power rating for a particular load. Solar arrays generate unregulated DC voltage in the presence of solar irradiations. The DC load can be powered from unregulated DC, but the natural variation in solar irradiation provides variable DC power. Therefore, a charge controller device is attached to the solar array to regulate the DC voltage. The charge controller intelligently operates the PV arrays at the optimal power point, also known as maximum power point tracking (MPPT). Additionally, the charge controller protects the battery from over and undercharging. The AC inverter converts the DC voltage from the battery or charge controller into usable AC (120V/240V, 50/60Hz).
The efficiency and quality of solar arrays, charge controllers, and inverters are an integral part of a successful PV system. Premier Energy Solution Jamaica provides state-of-the-art mono-crystalline solar panels, inverters another solar accessory at a very competitive price. In addition, Premier Energy is just a call away for all your queries and support in cost estimating and installing the PV system for your home or business.
PV system sizing for a typical household
Step1: Estimating the solar powered load
We can easily estimate the daily electricity consumption of a typical house either by listing the power rating of all the electric appliances or downloading the annual electric bill, which gives an average daily load as provided in the following equation:
Make a load table of DC-powered load and AC-powered load. The DC-powered load can directly connect to the DC bus or the battery.
|S/No.||Load Type (AC/DC)||Quantity||Power(W)||Usage Time (hr)||Consumption (Whr/day)|
Total DC consumption = 150+2400= 2550 Whr/day ………………………………..(1)
Total AC consumption = 300+1000= 1300 Whr/day…………………….…………..(2)
The DC to AC conversion results in minor losses. The solar array size should also compensate for these losses. Inverter losses are easily calculated from the inverter’s efficiency given in the datasheet. Considering the AC inverters as 90% or more efficient, the AC consumption can be obtained from the following equation
Total AC consumption = (1300 / 0.9)=1445 Whr/day …………………..………..(3)
Total power consumption = DC consumption …………………………..………..(4)
Total power consumption = 2550+1445 ≈ 4000 Whr/day ………………………..(5)
Step 2: Solar array sizing
Assuming the total sun hours in a day= 06 hours/day
Required Solar power= Total Consumption/ Sun Hours
Required Solar power = 4000/ 6 =666.6W ……………………………………..(6)
The required solar power should be overestimated by 30-40% for better performance, so we scale Equation (6) by 35%.
Required Solar power = 666.6W x 1.35 =900W ……………………….……..(7)
Therefore, the number of solar panels connected in the string must be equal to or more than Equation (7). We can use the solar panel starting at 100W to 300W. It is better to use higher power rating solar panels. For 900W output, we can use three 300W solar panels connected in parallel. We can find the open-circuit voltage and short-circuit current from the solar panel datasheet.
Open circuit voltage of single solar panel =17.2V………..………………..(8)
Short circuit current of single solar panel =19A……………………….…..(9)
Since we combined the three panels in series, the short circuit current needs to be multiplied by three as well.
Total Short circuit current of solar string =19A x 3 = 57 A……………..(10)
Step 3: Charge Controller sizing
The charge controllers operate the PV array at MPPT and they are designed to handle 25% more current than the total short circuit current. Therefore,
Total charge controller current = Equation (10) x 1.25 = 57 x 1.25 A = 71.25 A……..(11)
So, we can choose any available off-the-shelf charge controller above 71.25A.
Step 4: AC Inverter sizing
AC inverters experiences the surge current when the inductive appliance like fan/motors are switched on. Therefore, the inverters are scaled-up to prevent undue stress on the electronic switches. Since the expected maximum load is 4000W
Total inverter power = Equation (5) x 1.1 =4000 x 1.1 W = 4400 W…………..(12)
Any inverter above 4.4kW can be selected e.g. 5000W. Moreover, a modified sine wave inverter can save some cost instead of a pure sine wave inverter.
Step 5: Battery sizing
The maximum discharge capacity govern the battery size. It is recommended not to discharge the battery more than 70% of its full capacity. However, the battery size can be increased according to the required backup days.
For two days of power backup, the battery capacity is expressed as:
For a 4kW load with 48 hours backup time and 12V , the battery capacity can be related as:
The above calculation shows that a 1000AH battery bank at 12V can provide a backup for two days to a 4 kW facility even without sun.
In conclusion, solar energy is the future, and Jamaicans must embrace it if they want to create a better future for themselves, their families, and their country. With cost savings, reliable energy, and a boost to the economy, the benefits of switching to solar energy are numerous and undeniable. So why not make the switch today?