One of the discoveries I have made in the past few months is that my home consumes only around 600 watts of energy, even with two kids and the wife staying at home 99.5 percent of the time as they have been stuck at home, working and schooling for the past 14+ months.
Of course, that means no air conditioning. But 600 watts of average energy usage already accounts for one desktop, two laptops, a non-inverter refrigerator, a couple of electric fans, some LED lights, and an occasional water pump. That kind of energy usage is not bad, efficiency-wise, for a fully occupied home…costing around 4-5 thousand pesos in electricity bills a month.
It is when the aircon is turned on when energy usage jumps significantly. A 2hp AC unit will consume around 1,500 watts. But since our home was designed with large windows for maximum natural air flow, we don’t really need to turn on the AC unless it is a really hot day, usually during the summer months.
I’ve been observing our home’s energy usage closely these past few months because, as mentioned in my previous article, I have been seriously considering retrofitting the four PV panels totaling almost 1KW I DIY installed on my roof to be grid tied instead of being the current hybrid off grid type that requires costly batteries.
In the past, it was not worth it to get a grid tied or net metered system installed in my home because nobody is there to consume energy during the daytime hours when solar panels are generating free power anyway. According to my daily electric meter readings, our home currently uses 600W during the daytime when fully occupied. That means it probably uses only 200W max during the pre-pandemic days when the home was mostly unoccupied while the kids were at school and the parents at work.
With a low day time power consumption, it didn’t make sense for a homeowner like me to invest on solar panels and a grid tied inverter. A grid tied home PV system is maximized only if the home uses most of the energy the PV panels produce during the day. Selling back to the grid via net metering is ok, but since the home gets paid back only half the cost of electricity it generates since it is treated as a power generator instead of a consumer, the return on investment in that case takes twice as long.
Based on my experience over the last eight years of having a hybrid off grid system installed in our home, this type of system does not have an ROI because of the costly batteries. Because my current system was already starting to show signs of age, along with the new living conditions caused by the pandemic, I had to consider changing over my system to a grid tied one which at least has an ROI.
So…eight years after my DIY home PV journey started and one year after the world’s longest, strictest and most ineffective lockdown started, I’m finally getting my home grid tied and net metered. I should’ve started last year but who would’ve thought that our government would be so helpless against Covid? Right now, I’m assuming that my family will be staying mostly home for at least another year, or until we get a more competent government.
I’m changing my hybrid off grid inverter to a grid tied one, adding a couple of PV panels on my roof to increase capacity, and applying with CENECO to be net metered.
Hopefully, the application process is quick and painless and my ROI computations are correct. Based on the size and cost of my investment, ROI will be 3-4 years if my family stays home during the day forever, with the added bonus of being able to turn on an aircon during the daytime. If everything miraculously returns to normal and the home is empty during day time again, the ROI might take 5-6 years.
Whether the ROI is three years or six, what convinced me to shift to a grid tied system is that there is an ROI. If I kept my old PV system that needed batteries, I’d still need to replace batteries every 3-6 years, depending on the battery tech utilized. Such a system may give power security for critical loads in my home, which has become very important these past few days of almost daily power interruptions, but there is no ROI.
If you come to think of it, those who have been considering taking the PV route should take the leap now that most of us are stuck at home indefinitely. It is a sizable investment at the start but it should pay for itself within six years and after that, it becomes a smart move. If I had taken this route back then, I would’ve done paying by now and should be enjoying the fruits. Hopefully this time, I make the right choice.*