Sizing a Solar System After the Net Billing Change
A bigger system used to be an easy win under net metering, under net billing that's no longer automatically true, sizing now depends on how much of your own power you'll actually use versus export.
Size your solar array around your typical daytime consumption rather than your total daily usage, and pair it with battery storage to capture surplus for evening use, since exported units now sell back at a considerably lower rate than what you pay to import.
Start with your actual daytime usage pattern
Review your electricity bills for roughly when during the day you consume power, not just the total. A household empty during working hours has different optimal sizing than one with heavy daytime air conditioning or work-from-home equipment.
Battery storage now carries more weight in the decision
Since exported surplus is worth considerably less than it used to be, storing that surplus for your own evening use has become proportionally more valuable, factor battery capacity into your sizing decision from the start rather than as an optional add-on.
Get a design tailored to current rules, not old assumptions
Ask your installer directly how their proposed system size and battery capacity account for current net billing economics, rather than accepting a generic recommendation that might reflect outdated, export-friendly assumptions.
Why treating your electricity bill as raw data pays off more than estimating from memory
Pull your actual electricity bills from the past twelve months rather than relying on a rough memory of your average usage, seasonal variation between summer cooling load and winter usage can be substantial enough that a memory-based estimate meaningfully misleads your sizing decision, the twelve-month spread gives your installer genuine data to design around rather than a guess.
What genuinely happens when a system is oversized relative to actual daytime consumption
An oversized system under current net billing rules doesn't just fail to deliver its theoretical maximum return, it actively wastes capital on panels and inverter capacity that will spend most of their operating life exporting at the lower buyback rate rather than displacing your own retail-price consumption, this is a genuinely different, more costly mistake than it would have been under the old net metering framework.
Why your roof's actual orientation and shading pattern deserves a real site assessment
Beyond the numbers on your electricity bill, your specific roof's orientation, tilt, and any shading from nearby structures or trees genuinely affects how much of your theoretical system capacity you'll actually capture, a proper site assessment, not just a desk-based estimate from your address, is worth insisting on before finalizing your system size.
Getting a second opinion before committing to a specific system size
For a significant investment like solar, getting a design proposal from a second installer specifically to compare sizing rationale, not just price, helps you spot whether the first proposal was genuinely tailored to your usage or based on a generic template.
Straight answers to common questions
It can, depending on how well it's matched to your actual self-consumption pattern, an oversized system under net billing captures less value per exported unit than it would have previously.
Increasingly yes under net billing, since self-consumed stored power is worth more than exported power, get a specific calculation from your installer based on your actual usage rather than a general estimate.
If you're genuinely planning a major future load increase, discuss this with your installer upfront, since retrofitting additional capacity later is generally less efficient than accounting for it in initial design.
Household size is one input but actual usage pattern matters more, a smaller household with heavy daytime appliance use may need more capacity than a larger household that's mostly out during the day.
Yes, expected generation varies by season and region, a proper site assessment accounts for your specific location's typical solar irradiance pattern across the year, not just peak summer conditions.
South-facing orientation generally captures the most consistent sun exposure across the day in Pakistan's latitude, west-facing can still work well but may shift peak generation later in the day, discuss your specific roof orientation with your installer.
Standard inverter sizes are typically available in fixed increments, rounding up slightly to the nearest standard size is normal practice and shouldn't be seen as deliberate oversizing.