So it was right smack in the middle of this pandemic that the PV stars aligned and the opportunity to shift my hybrid-off-grid system to a grid-tied one presented itself.
Our home’s second set of lead acid, deep discharge batteries wore out, the inverter-controller broke, and my kids and wife were at home, consuming electricity 24/7. All I had left from my DIY hybrid-off-grid setup at that point were 4, 6-year-old PV panels on the roof capable of harvesting approximately 1KW from the sun.
I was shopping around for replacement components and naturally asked about the grid-tie option, which would be cheaper since there would be no more recurring battery cost.
Lithium ion batteries, while finally available, were out of the question because of budget constraints. The choice we faced were to either stay with the hybrid-off-grid setup or shift to grid-tie. The former gave our home the power reliability of a giant UPS at the added cost of batteries while the latter was cheaper and would even allow our home to sell the extra power generated by our roof back to the grid. Its only disadvantage was in case of brownouts, a grid-tied system would automatically shut down and by design produce zero power, even if the sun was blazing.
I have been telling friends who asked me about solar that as long as you intend to use the power your system generates, grid-tie makes better sense. But now that the opportunity to shift presented itself, I was having doubts. Now that I come to think of it, it was probably because I dreaded missing the unparalleled power reliability of a hybrid-off-grid system and a home where the lights and internet never go out.
After much thought, I finally decided that the benefit, however glorious, is simply not worth the cost so six years after my solar journey began, I finally made the decision to shift to a grid-tied system.
Shifting was easy. All I needed was to replace my busted inverter-controller with a grid-tied one and get rid of my old battery bank. And since there were now people at home 24/7 indefinitely, I figured I could redirect the “savings” from no longer needing to buy batteries to adding PV generation capacity aka more solar panels. The promise of a proper ROI also pushed me to maximize my resources so in the end, another “investment” was made and our 1KW hybrid-off-grid system became a 3KW grid-tied system.
The next part was tougher. Applying for a net metering agreement with Ceneco during a pandemic proved to be a more tedious process than I thought it would be. Long story short, I started my application and submitted requirements in May and my KWH meter was finally replaced with a net meter and the system finally connected to the grid in the last week of September.
It took four months of submitting documents, rewiring the home to comply with electrical requirements, and inspections. The part that took the longest, in my reckoning, was waiting for signatures and final approval. I don’t know if the pandemic mattered or it was sheer inefficiency on their end but that part of the process wasted almost 2 months.
During those 4+ months, my 3KW system sat there producing excess electricity it couldn’t sell back to the grid. Close monitoring of the app that came with the inverter that had been set so it cannot export electricity showed that my home which was occupied by a WFH wife, 2 high-schoolers and a household helper; only consumed an average of 600W during the day. That’s around 6KWH consumption for 10 hours daytime use.
From a green home design point of view, those consumption figures is something to be extremely proud of because it meant our big windows, high ceiling and cross ventilation works so the occupants don’t need to use air conditioning unless absolutely necessary. Of course it also means that my choice of a 3KW grid-tied system could be a bit of an overkill, however that should no longer be a problem during the summer months that now come with guilt-free AC use.
I have considered encouraging my kids and wife to use the AC more to take advantage of the free power during the day but at the same time I’m also happy that the habits we’ve formed, combined with good home design, are allowing them to live AC free in a dwelling where free AC is already possible.
No that my home is grid-tied and net metered, I’m looking forward to my next Ceneco bill. Based on my computations, the additional savings from being grid tied compared to the hybrid-off-grid savings we have already been enjoying for the past 6 years won’t be that big. Based on records, we have already been saving around 150KWh or approximately P1,500 per month because of solar. I’m estimating that getting grid-tied should result in P500-1k additional reduction in our electric bill, leading to an expected return on investment in around 4-6 years.
That is already a better projection than what my previous system could financially offer.
Hopefully my assumptions and figures are correct this time around. Wish me luck.*