How to power you electric fan with Solar energy

Posted by Felix Okoli on Thursday May 26, 2016 at 16:50:45:

In Nigeria, one of the things I've noticed that people do when they are really hot and want to cool down their body temperature is to visit places with air conditioning system. Among the places they visit to get a cooler temperature are banking halls, shopping malls and even churches.

Among all those places, the funniest one to me is going to banks and you'd see some Nigerians doing it while at the same time pretending that they've come to make a deposit or withdrawal. Even when they do have a transaction to do, it's normally in low volumes which don't really justify their reason for being there other than enjoying the air conditioning and they spend more time than usual at the bank as they won't be in a hurry to get out to meet the scorching sunlight. You can't blame Nigerians for visiting public places because of the extreme hot weather and low electricity supply.

There is no need to leave your home or office during the heat just because you don't have electricity because you can generate your own electricity and use it for cooling your space from the very sunlight that causes you so much heat. Yes, solar energy can be converted to electrical energy and this can be used to power electrical devices at your home or office.

Let's assume you have an electric fan that uses 60 AC Watts of power and you want to keep it powered on even after NEPA/PHCN has taken the power, you can connect it to solar energy using a solar panel, battery and inverter. The solar panel works to convert light energy to electrical energy and this is transmitted to the battery which stores it and then transfers it to your inverter which then provides DC power to your electrical fan. If your electrical fan can be powered with DC input power, then you don't need an inverter as it can be connected directly to the battery being charged by the solar panels.

So, let's assume you have a 50 AC watts electrical fan and you need to power it on for every hour up to 10 hours, then it means you need a total of 500 Watt-Hours of power.

The first thing to calculate is the battery AH that can provide that 500 WH and for a 12 V battery, you need at least a 50 Ah battery but you can also work with a 100 Ah 12V battery too which will be able to store and provide more power.

The next step is to find a solar panel that can charge that battery everyday sufficiently so that it can have enough power to power your battery for the 10 hours assuming it has at least 5 hrs of sunlight everyday. The calculation for 500 WH = 5 HRS * 100 Watts. We can make do with a 100 Watt Watt solar panel. If we want to minimize the effects of energy losses or inefficiencies in solar power, we can make do with a 150 to 200 Watt solar panel.

So, a 100 Watt solar panel that works with 5 hrs of sunlight, a 100 Ah Deep Cycle battery can provide sufficient power to a 50 Watt AC electrical fan for up to 10 hrs daily. If you want it to work for 24 hrs, then you'd need to double or triple the power inputs.

The other 2 basic things you'd also need for any solar power setup are the solar charge controller and an inverter. An inverter basically converts DC to AC power and this is necessary for AC electrical devices. For the above scenario, the calculation for your inverter rating required would be:

VA = Power/PF(Power factor) where 0.8 is the power factor

Since we need 50 watts per hour, the VA => 50/0.8 = 62.5. We can make do with a 65 to 100 VA inverter.

The final thing needed to complete your solar power system is the Charge Controller or Voltage Regulator. Its job is to control the charge input to your battery, prevent it from overcharging and prevents the solar panel drawing power from the battery when it's not charging it such as during the night.

So, a 100 Watt solar panel, 100 Ah battery, a 100 VA inverter and a solar charge controller can power your electrical fan along with a couple of low energy light bulbs for up to 10 hours of a day.

Some electric fans are designed to work directly with Solar panels and so no need to add any other stuff like inverter, solar charger or a deep cycle battery. All you need is connect the solar panel to it's internal battery to charge so that even after the sun goes down, it can keep working with it's battery power.

If you have a DC powered fan or one that can support both AC and DC input power, then it's much easier to just connect it to a solar panel. I have a rechargeable fan that requires only a 5W 18V solar panel to charge it's internal battery and when fully charged, it can last up to 9 hrs if its battery is working well. It has both an AC and DC input points. The one I use is Andrakk ADK2418 Rechargeable fan that requires just 43 Watts power to operate and it makes use of a 12V 7AH internal battery that allows it to keep working even after power goes off from the grid.