The short version: ten months in, the array is still tracking to a ~3.0-year payback. September recovered most of August's monsoon loss — generation rose ~38% to ~21.7 kWh/day and self-sufficiency climbed back to ~58.4% — but load rose ~25% alongside it, so the battery hit its 10–11% floor every day and never filled, and export was zero for the month. The three low-generation days in the first week are the tail of the flooding that hit Luzon, not equipment. The main finding holds and got sharper: the money is in the overnight base load, which rose to ~890 W in September — ~4.5 kWh bought at the full rate every night while the battery sits empty, ~₱2,230 for the month. If you're sizing a system here, the variable that generalizes from this single-site data is the always-on load floor, not panel count. Installing it needed the subdivision developer's approval first: Solar Panel Installation Application Guide for Lancaster New City. Once it was running I also took it through Meralco net metering — that paperwork is its own story: Net Metering Journey in General Trias.
Headline numbers
Annual bill cut
₱133,106
~66% of pre-solar bill
Simple payback
~3.0 yrs
on ₱400k turnkey
Year-1 generation
~8,190 kWh
~22.4 kWh/day baseline
CO₂ avoided
~5.2 t/yr
≈239 trees · 25,000 km
What the data shows
Self-sufficiency climbed from 54.3% in December to a peak of 76.5% in March, eased through the wet season to 59.9% in June, recovered to 66.5% in July, fell to the dataset low of 51.8% in August, and came back to 58.4% in September. Generation recovered ~38% to ~21.7 kWh/day, but household load rose ~25% to ~36.8 kWh/day on eight charging days (August had three) and a heavier overnight draw. The extra load absorbed most of the recovered generation: the battery peaked at 96% and never reached full, so nothing was exported.
No equipment fault is visible. Peak PV reached 5.44 kW (68% of inverter capacity), with zero clipping in 303 days. The three September days flagged as low generation (Sep 4, 5 and 7) sit in one run inside the tail of the August flooding, with output suppressed across the whole daylight window, and the array was back to ~30 kWh days by mid-month. Battery round-trip efficiency read 96.7% raw and ~96.5% adjusted for month-boundary carry-over; across ten months the adjusted range is 95.3%–99.2% with no downward trend.
The highest-impact lever is unchanged and grew: the overnight floor rose to ~890 W in September, from ~734 W in August, and with the battery at its floor every night it came almost entirely from the grid. Every 100 W trimmed off it is worth ~₱14,600 a year at ₱16.71/kWh. The second is charge timing: September's sessions drew most heavily at 06:00–07:00, before the array produces anything, and moving the start to ~09:00 puts them against peak generation. See recommendations →
Monthly bill impact
Month
Bill without solar
Net savings
Dec 2025
₱13,424
₱7,291
Jan 2026
₱11,736
₱7,039
Feb 2026
₱10,609
₱8,420
Mar 2026
₱12,464
₱10,520
Apr 2026
₱17,542
₱12,165
May 2026
₱18,633
₱13,162
Jun 2026
₱18,539
₱11,144
Jul 2026
₱18,001
₱12,129
Aug 2026
₱15,302
₱8,148
Sep 2026
₱18,439
₱10,765
Net savings peaked in May at ₱13,162, fell to ₱8,148 in the August monsoon, and recovered to ₱10,765 in September. September's grid bill was the highest in the dataset (₱7,674) because load rose and the battery emptied every night, and the feed-in credit earned nothing because nothing was exported. Each month is billed at the rate that applied then (rates moved from ₱14.41 in December to ₱16.71 in September); the ~₱133k annual figure is projected at today's rate.
Disclaimer: the report is AI-assisted. While the underlying data comes from the inverter export, the narrative analysis, recommendations, projections, and financial interpretation may contain inaccuracies. Verify critical findings against your own records, manufacturer specs, or a qualified solar professional before acting on them.