Super systems and useful solar

Start with the electricity you can use in daylight

With no battery or export credits, the valuable part of solar production is the part that replaces a grid purchase at the same time. A modest 3-4 kWp system can be a sensible starting point for some homes, but it is not a universal recommendation.

If 40% of consumption occurs in daylight, use that as a starting energy budget. Then check the hourly load: a large early-morning or late-afternoon demand may not coincide with midday generation.

Solar used now -> avoided grid purchase
Solar surplus  -> export / battery / curtailment

A PHP 10,000 bill, worked backward

For illustration only: assume PHP 200 of non-offsettable monthly charges and PHP 15.50/kWh for the remaining energy. Estimated use is (10,000 - 200) / 15.50 = about 632 kWh/month. A 40% daytime share is about 253 kWh/month.

At the education calculator's 3.8 kWh/kWp/day net-yield default and 30.4375 days/month, that daytime energy corresponds to about 2.19 kWp before panel increments. At 3.0 yield it is about 2.77 kWp. These are monthly-energy matches, not proof of an hourly match or an approved roof design.

Percentage return and total savings are different

A smaller, highly utilized array may recover its cost sooner. A larger array may save more pesos overall, yet have a longer payback if its additional output earns less or goes unused. Fixed installation costs can also make a very small array less economical per kWp.

Simple payback is installed cost divided by annual net savings. It is not a lifetime investment return: financing, degradation, equipment replacement and changing tariffs matter. Do not claim that the smallest system always wins.

• Compare six system scenarios

No net metering does not mean no coordination

Meralco asks customers to notify it even for self-consumption systems. Discuss the appropriate zero-export arrangement and controls. An unapproved surplus flow is not a substitute for net metering, and an unsuitable meter can record it incorrectly.