COST COMPARISON


Meralco charges P10 per KWH. A 40W flourescent lamp, used, say for 10 hours log 400WH or .4KWH . On an annual basis, that will be 144 KWH x 10 or P1,440. What will it be if we use solar energy?

Here are assumptions:

1. Solar Panels last 25 years. P200 per watt.
2. Controller last 25 years. P1,000.
3. The battery last 5 years. P5,000.


We first have to determine how much solar panels we would need in watts to light up the same bulb. Unfortunately, the relationship in watts is not one to one. There are losses when batteries are charged. It means , a 40W solar panel is not necessarily what we need to charge batteries for the 40W lamp. THERE IS THE TIME ELEMENT TO CHARGE AND THE TIME IT WILL BE LEFT ON. We will make one loose assumption at this point, that it takes 150 % more power to charge a battery. This means for example that a 15W panel exposed for one hour can supply 15watt-hour but the battery will accumulate only 10 watt-hr. Or, a 10W panel should be exposed 1.5 hours to light up a 10W bulb for one hour.

Ok, with this assumption, we would need to produce 400WH x 1.5 daily to power up the lamp for 10 hours a day. That will be 600 WH a day. To produce that in day, we need to know how much average sunlight we have available daily. In the Philippines, 5 hours is used. Thus, 600WH/5 is 120 watts. To get the cost, a 120W solar panel, costs P24,000. Over 25 years, that will be P960 pesos. The cost of the battery will be P5,000/5 or P1,000 per year. The controller is negligible. So, the total cost to produce the same power with solar cells is P1,960. Not a good proposition on the surface when Meralco would only charge P1,440. BUT IF WE TAKE INTO ACCOUNT PRICE ESCALATION, WE MIGHT BEAT MERALCO'S COST.
There are other benefits to the country like LESS OIL IMPORTATION AND LESS POLLUTION.

NOW SWITCHING TO LEDS WILL HALF THE COST! Now, that makes sense.

BK