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Grid tie?

My previous article discussed the dilemma I faced after the inverter-controller of my 6-year-old home PV system failed again. The equipment failure forced me to prematurely decide if my home was going to continue spending on batteries or if going grid-tied would be the way forward.

If I were to be brutally honest to myself, I’d consider this project a failure. I have not yet recouped my initial costs.

In my assumptions, I had expected the inverter that recently failed to serve my home for 10 years. I expected each set of battery banks to last 3-4 years. The reality was I had to shell out another P20K to replace the first set batteries after only two years and the 2nd set of batteries is already due for replacement by this year, after only three years of use. If and when I get the third set of batteries, hopefully at the latter part of this year, it will cost another P20K. By now I have already spend P40K on batteries alone. This mean, over the past six years or 72 months, I would’ve spend approximately P555 per month on batteries alone.

My estimated savings from using a battery-powered PV setup is around P500-P600 per month. So, at the end of six years, whatever savings I made from a lower electricity bill is just paying for the batteries.

My savings have not yet paid for the inverter-controller and the PV panels, which cost about another P50-60K for my modestly sized almost 1KW DIY system. In other words, going solar for me cost more than it saved.

The only thing it bought for me was protection from power interruptions. Having a battery backup for the critical loads of my home meant we never had to totally run out of power over those six years. The lights and more importantly, the internet, stayed on.

However, an argument can be made that my money could’ve been better spent on an emergency genset. A decent genset would’ve cost only fraction of what I paid for DIY PV system. It would’ve meant going out of the house and turning on the genset every time power went out, but I wouldn’t have shelled out so much moolah for the convenience of the lights never going out because of brownouts.

The lesson here is I should’ve chosen better equipment. A better quality inverter that might last longer than six years might cost a little bit more up front, but it can pay for itself with a longer serviceable lifespan. As for batteries, six years on, I still don’t know where I could get better quality or higher tech batteries that last longer. The convenience of having a battery bank for backup power is indeed costly.

If I could go back, I’d probably still do it but I’d go grid-tied, without batteries. There are less components to fail and no batteries to replace. Using the grid as a battery makes sense, and although there will be no power from the sun during those annoying 8-hour weekend brownouts courtesy of our electric cooperative, UPS units and an appropriately-sized emergency genset should do the job of providing seamless backup power.

My inverter died and the 2nd battery bank is near the end of its serviceable life, but I still have PV panels on my roof. This means I will have to decide between entirely abandoning the project entirely after six years and take the loss, or reconfiguring the system for a better way forward.

At this point, I am seriously considering converting my system to grid tied. The PV panels are already there. My home has been fully occupied since March 2020 and given our governments lame-ass response to the pandemic, my kids and wife will probably be home for another couple of months at the very least.

A grid tied PV system will provide enough solar juice to directly lower our electricity bill. And even if life goes back to normal and our home becomes empty during the daytime, net metering will still allow us to recoup our costs because of the ability to sell excess PV generated power back to the grid.

Being an early adopter comes with risks and rewards. Sometimes you win, sometimes you lose. In my case, I might’ve lost some money but I still learned a lot from this experience. The good thing is that while there may be some disappointment, I’m still pretty sure at this point that I’m not giving up on this project.*

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