Solar Power For Communities on Small Islands in the Philippines

This is dedicated to anyone living on a small island where electrical power is limited or not available at all and to anyone who is willing to educate and introduce ways of harnessing renewable energy for the benefit of island communities. 

Some islanders have managed to power up their household lighting and devices through petrol and diesel power generators. Solar powered emergency lights and mobile chargers are also being used but the durability of such devices is poor. Power generation from petrol or diesel engine is expensive. Islanders have to travel to main land by motor boats to purchase petrol and diesel. Motor boats consume liters of petrol or diesel too. Power generation via engine only takes few hours. Usually engines are used between 6:00 pm to 10:00 pm.

So far I only find two ways of harnessing renewable energy on a small island. It's wind energy through wind turbine and solar energy through solar panels. Possible tidal energy needs further research. Here, I will feature solar power's functionality, installation, advantages and costing. Many solar companies have proudly featured successful solar power system installed on commercial buildings, factories, and residential houses of wealthy people but I never saw any of their products installed or introduced to small island communities.

With solar power, communities can power up their household lighting and devices like the engine generator. Only that solar power does not have any moving parts or combustion mechanism that creates noises and carbon gases. So petrol and diesel consumption is reduced. Engine generators can be tied along with the solar power system through the use of battery charger that converts 220 AC from the engine generators into DC voltage, enough to charge a power bank. In case of solar power charging is low or the power bank is on low level, engine generator can back it up.
The image below shows a simple 12 volt DC system of an off-grid solar power. I recommend to use 12 volt DC system because there are some light bulbs, mobile chargers, and other devices that run on 12 volt DC. So that islanders have the option to use 12 volts DC output from the power bank instead of 220 volt AC of inverter's output.  Conversion of DC voltages to AC voltages requires also additional power to electrolytic capacitors, MOSFETs, and some active components. With direct connection between DC source and DC load, such power lose is omitted.

Solar panels have efficiency of 14 to 40 % electrical power conversion depending on their type. They are categorized into two in terms of crystalline used in a solar cell. These are the monocrystalline solar panel and polycrystalline solar panel. Monocrystalline solar panel are best used in full sun like in summer because it can increase its efficiency up to 40 %. Monocrystalline however, is sensitive to shading and produce less power on rainy days or cloudy days. Monocrystalline solar panels last longer compare to polycrystalline solar panels. Moncrystalline is more expensive than polycrystalline. Polycrystalline is best used in places where most days are cloudy or shaded with trees. But with full sun, the efficiency is up to 24 % only. It is cheaper than the monocrystalline but it has shorter life span compare to monocrystalline. Solar panels are best deployed in an open space area away from shades of trees, deployed on a roof with 30 degrees slope and facing the southern sky. Solar panels facing the southern sky are exposed to direct sunlight for many hours. Monocrystalline are widely used in the Philippines because of its high efficiency at full sun and also the country has more sunny days in a year. Some advanced consumers use both monocrystalline and polycrystalline altogether but with separate circuits.

solar array

identical solar panels connected in parallel retains voltage output but increases current output

Identical solar panels connected in series increase output voltage but retains current output

In DC circuits, avoid the use of long cables. Cables with DC power, are hotter than in cables with AC power. The longer the cables, the bigger the power lose. DC cables from solar panels, power banks and to DC loads and power inverter should not exceed to 10 meters in length. Solar panel cables and connectors are MC4 type by standards. If MC4 is expensive for you, you may use a pair of two different colors of DC cables or battery cables with at least 20 to 30A ampacity for each solar panel. You may omitt the use of MC4 connectors and use wire splicing instead. Battery cables can be automotive cables that have large ampacity. Terminal lugs are widely available. Copper terminal lugs are the best but others made of metal alloy work well too.

MC4 Connectors

A power bank is made up of batteries connected in either parallel or in series circuits depending on the battery voltage output and the voltage system of the power bank. A deep cycle lead acid battery is recommended as it store more energy than a typical car battery. But deep cycle batteries are designed for long term but low current operation. Deep cycle batteries have more plates than its electrolytes. A car battery has few plates but more electrolytes. They are designed for high current operation but in short term and they are widely used in ignition system that requires high current startup. Here, a 12 volt  DC system is featured.  So if each of your battery has 12 volts output, they can be connected in parallel to each other. The more batteries in parallel connection, the bigger the energy storage and the torque. Batteries in parallel should have the same type, brand, voltage and storage capacity in AmpereHours (AH).

 Connecting batteries of different ampere hours (AH) can destroy the entire power bank, the charge controllers and even the power inverter. Batteries of higher AH will become parasitic and can draw lots of power resulting to premature draining of power bank. The more batteries in parallel connection also extends the life of each battery because the total operating current is shared to each battery those reducing the speed of decaying of plates. The image below shows an example of battery connected in series. Connecting batteries in series will give a sum of each battery voltage.

48 volt power bank (four 12 volt identical batteries connected in series)

DC switches can be replaced with AC breaker at 30A minimum per solar panel to charge controller and 50A minimum per charge controller to power bank. AC breaker amperage for inverter and dc load may vary depending on the working current.

Example of a DC switch or breaker

Charge controllers and ac/dc battery charger are widely available in electrical and electronics supply stores, and online shops. In a 12 volts DC system, a 30A 12v/24v charge controller is commonly used. Each 30A 12/24v charge controller can be connected with solar panels up to 400 watts. Solar panels are connected in parallel for charging 12 volts DC power bank and are connected in series (of two solar panels) for charging 24 volt DC power bank. Charge controller and AC/DC charger have the same function and voltage/amperage range. They only differ on power source input. Charge controller uses the electrical energy generated from hydro, wind, and solar while AC/DC charger converts alternating current from the mains into direct current to charge or power a DC load or battery.

MPPT charge controller

To start solar power generation, make sure all breakers and switches are turned "off". To begin;
1. Switch "on" the breaker between charge controller and power bank. If AC/DC is connected, switch "on" also the breaker  that is connected to it to the power bank.
2. Switch "on" the breaker between solar panel/s and the charge controller.
3. Switch "on" the breaker between the power bank and the power inverter. If you want to connect DC load, switch "on" also the breaker that is connected to it from the power bank.
4. Connect loads to test.

To shut down solar power generation, unplug and disconnect the loads from the circuit first then follow this sequence:
1.Switch "off" the power inverter
2. Switch "off" the breaker between power bank and power inverter and  the breaker between power bank and DC load.
3. Switch "off" the breaker between solar panel/s and charge controller. Switch "off" also the breaker between AC/DC charger and power bank.
4. Switch "off" the breaker between the charge controller and power bank.
Failure to follow the sequence of turning on and shutting down the solar power generation will result error to charge controllers and charging will not start.

Material and Device price in Php peso:

Charge controller or AC/DC battery charger 12/ 24v 30A= 450.00 to 2,500 Php
Solar panel from 80 to 300 watts= 4,500 to 14,000 Php
Deep cycle batteries from 50AH to 150AH= 7,000 to 14,000 Php for branded while 2,000 to 7,000 Php for low end brands.
DC switch or AC breakers = 350 to 1500 Php
1500 watt and up pure sinewave inverter= 3,500 Php and up.
DC cables, Battery cables, MC4 cables= from 40 to 150 Php per meter.
Mc4 connectors, terminal lugs= 30 to 150 Php each or pair.

Like AC/DC charger, solar power can be tied with hydro power and wind power generators, as long as they have the same direct current output that matches the charge controllers and power bank.

If you have an islander friend or relatives, or you want to help, please spread  this post to them.

Conserve Water by Installing Pedal Controlled Valves

Water, the universal solvent of life, is becoming scarce to some places around the globe, as it can no longer meet the demands of daily usage. There were lots of communities do not have access to clean water. As the population grows, the demands for agricultural products, and power generation increases. Both agriculture and power generation needs water. Some places are already experiencing drought because of uncontrolled expansion of agricultural farms that produce water-hungry crops like avocados. These crops yield more if you feed them with water well. The distribution of water to residencial areas has been minimized. In power generation, most power plants are drive by steam turbines. You cannot create steam without water. Nuclear power plants, coal power plants, geothermal power plants and diesel power plants that use different fuel to generate power, still need water to move steam turbines to drive generators. Sea water is now being filtered and desalinated with the use of technology to counter water scarcity. However, the process costs a lot of money for power requirements, treatments, and maintenance.

You should start conserving water now. Start it at home. One way of conserving water is to install foot pedal controlled valves to your showers or faucets. How it works? We use to wash our body or our hands with soap and wash the dishes with dishwashers, right? Most of us leave the faucets open and let water flows while we are busy rubbing our hands with soap or while we are applying  detergent to dishes. It may take seconds to minutes before we are going to rinse them again with water. Some may close the valve but others don't. It is also uncomfortable to close the faucet while you are rubbing your face with soap or  facial products while your eyes are closed.

With pedal controlled valve installed,  your foot would be your third hand. While your two hands are busy, the third hand will control the water flow. You can save water as it stops the water from flowing out of your faucet while you are busy with soaps. Pedal valves are widely used in drinking water fountains. Some kitchen sinks, aside from pedals, come with spray heads or hand triggered sprinklers.

Pedal valve has different types to choose from, in terms of mechanism. The oldest one is the mechanical pedal valve that uses springs, flappers, or rubber balls. There is also electronic pedal valve that uses low voltage circuit to drive an electronic or solenoid valve. There is also a pneumatic type that uses oil that moves a sealed mechanism inside the pedal main casing. Pedals can be made of brass, metal alloys, stainless steel, and plastic. They are widely available on hardware, home improvement stores and online shops like Amazon or Ebay. Below is a link to a good quality pedal controlled valve available at Amazon.

LuckLoy floor mount single pedal valve

How to Grow Ginger ( The Business Way of Propagating Gingers )

Plan to propagate a high value crop in the Philippines? Why not try gingers? Ginger price and demand in the markets is high. Either indoor gardening or commercial way of propagating ginger, you should take note of  some important information  on how ginger rhizomes grow. Rhizome is a type of plant that has stem that grows in the soil or surface of the soil that shoots out roots and produces stalks. 

1. Ginger rhizomes grow and spread horizontally in the soil and grow stalks vertically to form foliage.

2 Rhizomes do not spread forever. Most ginger rhizomes cover only a one to two square foot of the soil and begin producing stalks depending on the variety.

3. An exposed part of the stalk can be covered with soil to produce and spread another batch of rhizomes.

4. Gingers spend most of their lives growing vertically by nature. As they get older, they are more interested in growing foliage and reproduce through pollination.

5. Gingers hate wet clay soil and gravels. They love soil mixture of loam and sand.

Gingers are widely propagated through rhizome cuttings. However, you may apply the use of ginger seeds too. A rhizome of a size of a person's thumb, can reproduce batches of rhizomes. The image below shows possible  cuttings to propagate gingers.

Gingers need only a shallow dug soil of up to 3 inches deep. Each cuttings are spaced 30 to 40 cm from each other. Ginger are best planted in blocks and boxes to allow the water to be drained right away. Prolong exposure of rhizomes to water will result to rotting. To earn more yields, rhizome batches should grow in layers.

I recommend to use soil box frame. It can be made of wood or plastic as long as the box and soil mixture wont hold water. The height should be 30 to 40 cm

Fill the box with 4 inches thick of  soil and sand mixture

Prepare the rhizome cuttings and soak them in warm water overnight.

Place the rhizome cuttings in the soil at a depth of 3 inches and cover again with the soil. Allow 30 to 40 cm spacing from each rhizome cuttings.

Allow the cuttings to grow and spread. Water once a day or once every other day depending on the weather. Gingers are best grown in tropical areas.

Once new sets of rhizomes reveal on the soil surface. Add 3 inch thick of soil and sand mixture in the box. This will allow stalks to produce another batch of rhizomes and the spreading of newly grown rhizomes will happen once again.

 As you observe,  rhizomes can be multiplied  layer by layer. Once another batch of rhizomes reveal on the soil surface again, add again another 3 inch thick of soil and sand mixture. The process can be repeated multiple times within 10 to 12 months. The number of layers may vary on the rhizome variety type and the way of caring the plants. The more the layers of rhizomes, the bigger the yield is. Gingers are sometimes magnesium hungry. If your soil and sand mixture does not have enough magnesium content, you may apply the use of scientist version of "ormus". It is a by-product of sea water and caustic lye reaction. It is pure basic and monoatomic crystalline that can be mixed with water to get the a desired pH  for your plants.

"Malunggay" Horseradish Tree Business (How to propagate horseradish trees)

Horseradish tree or malunggay in Tagalog, kamunggay in Bisayan and Cebuano, and kalamunggay in Mindanaoan, is a tree native to tropical Asia that has been cultivated for its edible leaves and young pods. Known for its nutritional content, oil is extracted to be used as food supplement. Malunggay has high content of calcium and some vitamin C. Calcium is the mineral that is being featured in malunggay. From noodles, ice cream, juice and bread, malunggay gains popularity because of its high calcium content. Aside from food-related demands, some farmers were ask to plant more malunggay trees in order to supply manufacturers of food supplement pills with good demands.

Supplying malunggay to manufacturers could be a fortune. Would you like to farm malunggay trees for them? If yes, is your soil ready? Remember, as I mentioned earlier, that malunggay contains high calcium but the question is where did the calcium came from? Is it by magic? Of course not, it should  have came from the soil. The roots will absorb that calcium for the malunggay to survive. Soil with low calcium content will stunt the growth of malunggay. Most malunggay seedlings planted on low calcium wont live long and only few will survive with stunted growth, fewer leaves and seldom pod formation. If your soil is made up of limestone or lime soil, then congratulations, you are qualified to propagate malunggay trees.

In my older post entitled "1 Kilowatt Solar Power Project in a Farm" I mentioned a 4 hectare farm. Half hectare of the farm will be planted with malunggay trees. The farm is going to supply  a downtown market for edible use and to a herbal supplement manufacturer in Cebu City  for oil extraction. Malunggay trees can be planted either by seeds or stem cuttings. Most farmers plant malunggay tree's by stem cuttings. It can be done by cutting down stems into short stems which have 2 inches of diameter and planted vertically and spaced up to 50cm apart in a row.

 But only few know that long stem cuttings can be planted horizontally which gives more sturdy and healthier grown trees. To do this, you will only dig a straight row with 5 inches deep and 5 inches wide. Place the stem cuttings horizontally in line with the dug row and cover with soil.

Extending a Low-End and Cheap Sealed Deep Cycle Battery Life

Five years ago (2014) I built a 1 kilowatt solar power generator in our house. At that time, building a solar power was more expensive compare today. I have purchased four 200 watts solar panels that cost 15,000 pesos each, a 2 kilowatt 12 volt dc to 220 volt ac off-grid power inverter which costs 16,000, a 12/24 volt MPPT charge controller which costs 1,900 pesos, MC4 cables and connectors, battery cables and the batteries. It was really difficult for me to build a power bank that stores at least 500 AH of energy. Not because that I do not know how to build a power bank but the costing that gives me headache. At that time, genuine deep cycle batteries are already expensive. A 150AH battery  costs 13,000 pesos and I need three to four of it to create a bank which will cost me 52,000 thousand excluding battery cables and terminal lugs. Luckily I found a store that sells solar items and batteries. It was CD-R King. I found 200AH deep cycle batteries that cost 4,900 pesos each, way cheaper compare to the genuine ones. So I will only need three of it and will only cost me below 15,000 pesos. It was a risky choice because I am aware that CD-R King sells cheap and low end products that have low durability. Since I do not have enough money and I was very excited, I purchased the CD-R King batteries. 

I have completed my solar power generator and it was able to power most of our home appliances,  electronic devices, lighting and lately our CCTVs. Only the air conditioning, refrigeration, and microwave oven were not included in the solar power circuitry. I also connected a manual transfer switch  between outputs of solar generator and a breaker from mains power supply, so that if charging is low and batteries are less charged, we can easily switch to mains power supply. The generator worked fine for 2 months until it showed problems. The power bank gets easily fully charge for just 1 to 2 hours and  drains in 1 hour or less. At first I tried to swap a newly purchased charge controller to the charge controller installed in the circuit. Same problem occurred. I was already suspecting on the batteries but still I made another way of troubleshooting by temporarily replacing the inverter with the inverter I borrowed from my friend and the problem still occurred. So finally I began to check the batteries. I managed to open the plastic sealing on top of each batteries. There were holes  sealed with rubbers and I also unsealed them. What I found inside where layers of cottons which were already dried up and only the bottoms are wet. I did research online about deep cycle batteries, how they made of, types, etc. I have learned that adding distilled water to a dried up battery will restore its capability of storing energy. Of course this will only apply to batteries with plates that are still in good shape. I was not really sure if the batteries where experiencing leakage where the water evaporated and escaped out from the holes or the manufacturer purposely fill the batteries with low amount of water and acid mixture so that the product wont last long. I purchased liters of battery water sold by a gasoline station "Shell"  near in our house. 

I used a plastic funnel with empty ball pen casing as nozzle to fill up the batteries. (Caution: Battery solution is toxic for your brain cells. Do the refilling in a well-ventilated area and wear a safety mask.)  It costed me 7 liters of battery water to 3 deep cycle batteries as shown in the above actual picture. I  resealed the batteries with the rubber caps. I added epoxy adhesive to ensure air tightness.

The result was unbelievable. The bank has restored its energy storage capacity. The normal solar power charging and usage has restored. Believe it or not, the batteries are still working fine up to these days. Last year, I unsealed back again the batteries. Surprisingly, the liquid levels remain almost untouched. I filled again the batteries with the same battery water I used before. The bank did not even emptied a 1 liter bottle of battery water.

This method might work to other brands of deep cycle batteries that are used not more than two years. This might not work on gel-type batteries. The batteries I am talking here are all lead - acid batteries. 

1 Kilowatt Solar Power Project in a Farm

On July 2019, we will be making a 1 kilowatt solar power project to power a 4 hectare farm located in a mountainous forested land where power from the grid is not available. The project is part of the 2 Kilowatt Power goal we are going to achieve. The entire farm will be powered by a 1 kilowatt solar power and a 1 kilowatt hydro power. The project would require four solar panels, power bank, a homemade Pelton wheel, charge controllers, an off grid, pure sine, power inverter, dc breakers, connectors and cables. I will only feature here the solar power installation.

Like in the previous post about a 4 kilowatt uninterruptible power supply project, the setup is a 48 volt direct current system. So four batteries (12 volt each) are connected in series to form 48 volt bank. Each battery has 200AH energy storage capacity. A 48 volt MPPT charge controller to charge the battery bank, four solar panels (250 watts each) connected in series as the source of  power, and a  3 kilowatt pure sine wave power inverter with 48 volt dc input and 220 volts ac/60 hertz output to run a load, are the primary connections of the circuitry. Below image shows a block diagram of both solar and hydro power of the project.

Solar panels of monocrystalline type would be used in the project. Each rated 250 watts with up to 40 % efficiency at full sunlight and proper ventilation. We may cut down some trees for this project to avoid shading. A small shading on the solar panels can drop the power output of the entire array to 80-95 %. The advantage of higher dc operating voltage over the lower one is it requires smaller cable size to reach a certain power output. The higher the voltage, the lower the current in the circuit, so the smaller and colder the cable is.

Deep cycle lead-acid batteries are to be used to create a power bank. Each battery has 12 volts and 200 AH energy storage capacity. They are also connected in series to form a 48 volt bank.

The charge controller must be MPPT (Maximum Power Point Tracker) and can handle 48 volts and 30 amperes to charge the power bank. The image below shows an example of a MPPT charge controller. Depending on the manufacturers, some charge controllers show different looks. Usually it has terminals for solar or any dc source, batteries, and controlled output, led indicators for charging and battery level, work mode preset button and control keys.

charge controllers

DC switches sometimes called isolators or dc breakers should be connected in between solar panels and charge controller, between charge controller and batteries, and between batteries and power inverter. Most dc switches comes with built in protection fuses and high voltage bypass and dc blocking capacitors. Fuses will protect the circuit from overloading and bypass capacitors will protect switch contacts from high voltage sparks. The switches should be 30 ampere at least. they can be single pole or double pole type. Depending on the manufacturer, sometimes dc switch comes with a reset button.

dc breakers

Battery and inverter input cables should have a minimum ampacity of 30 amperes. The best terminal lugs are made of copper for better conductivity and produce less heat compare to terminal lugs made of zinc, antimony or steel alloys. Provide also cable color coding for the circuitry. Usually in direct  current circuity, red is used to indicate postive terminals of batteries, input terminals of  dc devices and dc cables. Black is the best color to indicate negative of direct current circuits. But for solar panel cables, like the MC4 cables, both positive and negative are of color black. Only the MC4 terminals and connectors will indicate the polarity of the circuits. You may even use a polarity tracker or a multitester to indicate the polarity. 

 MC4 connectors

 Terminal Lugs

A pure sine wave power inverter should be used in the circuit. Pure sine wave  inverters provide the same alternating current wave form like from the mains power supply. It has working frequency  of 50 to 60 hertz which most appliances or lighting devices run at. There is also another type of inverters that provide modified sine wave alternating current. They are much cheaper but not recommended to power on most loads. Modified sine wave can destroy induction motors like from the electric fans, ceiling fans and ac motor pumps. It produces humming sounds in most devices that run from converted ac input to dc output circuits. It can damage also some dc circuit as well. There are also three types of inverter according to output connectivity. We have the off-grid inverter where its output is independent from the grid power source, the grid-tied inverter which the output can be synchronized with the mains voltage and frequency and the hybrid off-grid and grid tied inverter which can work independently or grid tied. On this project, since access to power from the mains is not available, we are going to install an off-grid type of inverter. An off-grid inverter has fixed dc voltage input and an independent 110 or 220 volt/ 50 to 60 Hertz output. This project would use 48 vdc to 220v ac conversion inverter.

 power inverter

The AC output would be transmitted through THHN 8.0 mm2 cables. The solar station is made up of steel angular bars, 2 inches diameter Galvanized Iron pipes as columns, concrete flooring up to 30 centimeters thick, a rear wall that can be made of plaster or concrete, conduits and an entrance cap for distributing AC power to the loads. A 3/4 LB connector and entrance cap is mounted at the upper center of the rear wall. The roof can be a corrugated or any type witch 30 degrees angle slope.

The image below shows the entire circuit diagram of solar power project.

All dc switches and power inverter should be at "OFF" mode before installing and operating the solar power circuitry. You must follow a switching sequence to start or stop a solar power operation.

Starting a solar power generation:

1. Turn on dc switch connected between the charge controller and batteries.

2. Turn on dc switch connected between the charge controller and solar panels.

3. Turn on dc switch connected between the batteries and the power inverter.

4. Switch on the power inverter switch.

5. Connect the loads. It is better also to test the output with multitester before plugging a load.

Stopping a solar power generation:

 Switch off all the switches by reversing the above steps.

The solar power, along with the hydro power project, is expected to power a station house with interior lighting, water heater, radio and television receivers, farm perimeter and block lighting, internet modem with wireless LTE connection, laptops and mobile devices.

Building A Solar (Piso Gadget Charging Station)

Are you interested in piso machine business? From ATMs (Automatic Tubig Machine), pisonets, coffee vending machines, pisoWIFIs, and mobile charging stations; piso machines are found almost everywhere in the Philippine cities and crowded rural areas. By inserting coins in the machine, you get what it offers. 

Why not build a piso machine that can charge smart devices like smart phones and tablets and offers a wifi with internet connection at the same time,and a  machine that is powered by solar energy to electrical energy?

Here, I designed a solar powered charging station. It is made up of wooden enclosures, solar panel/s, charge controller, battery/s, coin box with timer circuit and coin slot circuit and car mobile charger with multiple mini USB (Universal Serial Bus) plugs.. The station requires only a little space with good roofing. Mobile phone chargers designed for cars run at 12 volts dc.

The closet could be made up of plywood or ply board. You can paint the outer surface either buy brush or spray. You may use vinyl or wood laminate. The edges can be covered with aluminum or rubber edgers. Depending on your design you may extend the numbers of charging ports but you may extend the solar panel and battery size or number.

The machine is best deployed inside a business establishment such as  a convenience store, eatery and cafe. You may omit the use of solar panel and install with a dc power supply of 12 volts which are widely available in most electronics stores. The machine can be deployed away from your house or business establishment since it is solar powered and off the grid. Make sure,  if it allows Wifi connectivity, the modem must be an LTE (Long Term Evolution) type. A modem that is powered by an LTE sim. Make sure there are openings near the circuits for easier installation and easier access for maintenance.

You may choose any of the closet where to place the battery/s and modem.

It is best to mount the charge controller on top of the machine. The image below shows an example of mounting the charge controller.

The length of cable between the solar panel/s and charge controller must not be too long. The longer the cable, the bigger the power loss. Unlike alternating current, direct current makes cable hotter. It is not necessarily to install exhaust fans on the machine. The timer and coin slot circuits draw less current and produce less heat but make sure to create ventilation holes near the circuitry. Connecting exhaust fans in a solar powered station is not a good idea. They consume power too and drain your battery/s.

The image below shows a charging station deployed on isolated location.

The best direction where a solar panel faces is on the south. The sunlight exposure from this direction lasts longer compare to any other direction. Avoid the solar panels from shading. A small shading can can drop the charging current up to 95 %. For a three charging port station, I recommend to use at least 100 watts of solar panel, a 30A 12 volt charge controller and a 50AH deep cycle battery. You may extend the number of solar panels and batteries. Since timer and coin slot circuit run at 12 volt dc, the solar power must be a 12 volt setup also. A 100 solar panel can charge a 12 volt battery. If you wish to add an extra solar panel, it must be connected in parallel with the existing solar panel.  Connecting two or more solar panels in series, to charge a 12 volt battery is not recommended. The panels would still charge the battery but very slow and would damage the charge controller. If you intend to connect solar panels in series, you must connect the batteries also in series and replace the charge controller with a one that can handle the battery output voltage. Like for example, if you want to connect three panels in series, then connect three batteries in series. If each battery has 12 volts output, the total output voltage would be 36 volts. So make sure your charge controller is rated also to operate at 36 volts or higher.

The image below shows the block diagram of the machine (does not include the WIFI feature): Each cabinet has coin slot and timer circuit. So a total of three coin slot circuits and three timer circuits. Aside from car mobile usb chargers with multiple charging plugs, you may add a usb receptacle if users prefer to use their own usb cable.

The image below shows a block diagram which includes WiFi Connectivity: Most modems run at 12 volts dc.

Making a Piso Jukebox

Do you own an eatery? A beer house? Or a Cafe? Do you play background music inside the premises? Why not build a Piso Jukebox? I know, it sounds old school but you can build a modern version one. A jukebox is a machine that plays a selected music when a coin is inserted. It is a compilation of music recordings that are stored in vinyl discs. The machine has a  complex mechanical means of selecting and playing vinyl discs.
In this design, the audio amplifier and exhaust fan turns on if a coin is inserted. You can select music or video music in an android or apple tablet media player. A tablet's audio signal can be amplified by an audio amplifier through stereo RCA connection. A tablet has 3.5mm stereo phone jack where we usually insert a stereo 3.5mm plug of a headset. You can purchase a 3.5mm stereo plug to stereo RCA plug adapter or cable. Most audio amplifiers use RCA jacks as audio signal inputs.

The image above is the design of jukebox I have sketched up. I have always seen jukeboxes shaped like this inside beer houses when I was a child in the early 90's. I thought they were electric organs or pianos. I never saw any of them in operation. They were just left ignored and some are  dust covered. At that time sound box with cassette players and VHS were popular, and video karaoke was on development.

The machine I designed requires a coin box circuit, audio amplifer, loudspeakers or sound boxes with loudspeakers and tweeters, an exhaust fan, audio cable,speaker wires, smart tablet with updated music playlist, and the jukebox chassis itself. You can create your own chassis design. You can choose any audio amplifier but I recommend a high wattage one at maximum of 500 watts. Make sure the power output and impedance are matched to both the amplifier and the loudspeakers. Loudspeakers with power range from 300 watts and above, need a minimum of 12 inches in diameter size. Smaller diameter will result to premature overdrive and distortion. I prefer to use a two-way passive speaker system, an instrumental and tweeter tandem. Woofers will enhance the desired bass response. If you plan to place woofers, it is better to have it on a separate amplifier and soundbox. Woofers can ruin other loudspeakers. They cause distortions. I prefer to use Sakura brand amplifier. It is cheap but powerful and durable. The best preset for tone control is 60% bass, 50% midrange, and 75% treble. The main volume should be set at 50% to 60% to avoid overdrive if the audio signal coming out from the media player is too high.

The tablet can be mounted on the front wall of the jukebox either by using  corner clamps screwed or make insertion hole that fits the tablet dimension and the depth of  hole should allow the tablet touch pad surface in line with the wall's surface. You may offer online media streaming app like Youtube app. The best media player software is VLC. It is free to download and install. It supports various media file types.

VLC media player link: https://www.videolan.org/vlc/index.html

The coin box is made up of a coin slot circuit, digital timer circuit, and a dc power supply. 

The circuits usually require 12vdc to operate. They are widely found in electronics stores and widely used in Piso machines like pisonet, tubig machine, and ready-made coin boxes.

The higher the power, the hotter the surrounding is. Make sure to install an exhaust fan at the back portion of the jukebox to expel out heat inside the box and maintain lower temperature. Electronics archenemy is the temperature. I prefer to use an induction motor type that runs in AC. It is easy to connect. It can be plugged in parallel with the audio amplifier.

To learn on how to make a coin box, there are lots of free tutorials online to watch.

I suggest to set the timer from 5 to 6 minutes per coin trigger. So just insert a 1 piso coin and the amplifier switches "ON" up to 5 or 6 minutes depending on your configuration of the timer circuit.