Guides · Faisalabad, Lahore, Punjab
Year One Review: Solar Output vs Estimate and How to Compare Them
Short answer
After 12 months, compare your solar output vs estimate by taking the total units your system produced in the year, dividing by its panel capacity in kW, and checking that figure against the estimate in your proposal and against the Punjab planning range of roughly 1,300 to 1,600 units per kW per year. A small gap is usually weather. A large or growing gap, especially in clear months, is worth an engineer's look. Then check the second number that matters just as much: how many of those units you used yourself.
This guide is for owners who have had their system for about a year. If yours is newer, start with your first 30 days with a new solar system.
Why a year, and why now
A single month tells you little. Punjab output swings from strong spring days to short, foggy winter days, so only a full year shows whether the system performs as planned.
There is a practical reason too. Solar Works Pakistan's service warranty runs for one year under the applicable project terms. Doing the review in month 11 or 12 means any issue you find can be raised while that warranty still applies. Panels, inverters and batteries carry their own manufacturer warranties per product; see our solar warranty guide.
Year-one review
Bills
12 months before and after
Output
Against expected yield
Faults
Alarms and service visits
What you need
| Item | Where to find it |
|---|---|
| The estimate | Your proposal or quotation: expected yearly units, and the assumptions behind it |
| System size | Panel capacity in kW (DC), from the quotation or handover file |
| Monthly generation | Your monitoring app: monthly or yearly kWh |
| 12 electricity bills | Before and after solar, if you have them |
| Net billing records | Import and export units, if you have an agreement |
| Your notes | Outages, cleaning dates, inverter alarms, new appliances |
If the app has gaps, for example weeks when the Wi-Fi dongle was offline, note them. Missing data is not missing production, but it will make the yearly total look low.
Step by step: the year one review
Step 1: Get the yearly total
Add the 12 monthly generation figures from the app. Use the inverter's own total where possible.
Step 2: Work out units per kW
Divide the yearly total by your panel capacity in kW. This figure, called specific yield, lets you compare systems of any size.
Example arithmetic only: a 10 kW system that produced 13,800 units in its first year has a specific yield of 13,800 ÷ 10 = 1,380 units per kW.
Step 3: Compare with the estimate
Divide actual by estimated. If the proposal estimated 14,500 units, then 13,800 ÷ 14,500 is about 95% of the estimate.
Also compare with the planning band in our guide to how many units a solar system produces in Punjab: roughly 1,300 to 1,600 units per kW per year for a well-installed, south-facing, unshaded system. A roof with shade, an east-west layout or a flat tilt can sit below that band and still be working correctly.
Step 4: Look at the shape of the year
Put the 12 months side by side. A healthy system follows the seasons: highest in spring, close behind in summer, lower in autumn and lowest in winter, often around half of spring. Look for a month that breaks the pattern.
- One low month usually points to weather, an outage or a period offline.
- A steady decline month on month in similar weather points to dirt, a developing fault or new shade.
- Low output only at midday on sunny days can point to voltage-rise trips or export limits.
Step 5: Check self-use
From your bills and net billing records, work out how much solar you used yourself versus exported. Under net billing, each self-used unit saves your full tariff, while each exported unit earns much less. Two systems with identical output can save very different amounts. Our guide to sizing under net billing explains why.
Step 6: Revisit the savings estimate
Put the actual numbers into the method in how to estimate solar payback: actual units, actual self-use share, and the tariff you actually paid. That gives you a realistic picture for the years ahead. It is your own calculation, not a guarantee.
Common reasons for a gap
| Reason | What you see | What to do |
|---|---|---|
| Weather year | All months a little low, worst in winter or monsoon | Usually nothing; compare with next year |
| Dust | Gradual drop between cleanings; jump after rain | Clean more often in dry months. See panel cleaning |
| New shade | Drop at certain hours; often after a tree grew or a tank was added | Check the roof. See solar panel shading |
| Load-shedding | Zero output during outages on an on-grid system | Normal: anti-islanding turns the inverter off when the grid is down |
| Grid voltage rise | Inverter trips on sunny afternoons | Report it. See why inverters trip on high grid voltage |
| Export limit or zero export | Output flattens at midday when the battery is full and the house load is low | Not a fault; production is held back by design. See zero export devices |
| Inverter clipping | Flat top on the midday curve on the clearest days | Expected with a high DC/AC ratio. See inverter DC/AC ratio |
| Monitoring gaps | Missing days in the app | Fix the connection; the system may have been producing |
| Early panel ageing | A small first-year drop, part of normal degradation | Check the datasheet figure. See solar panel lifespan |
| Equipment fault | One string or MPPT much lower than the others, or repeated alarms | Call for service |
Gaps that are not faults
Two items in that table catch owners out. On an on-grid system, the inverter switches off whenever the grid is down, so a year with heavy load-shedding produces less. On a hybrid system with export limited, the inverter deliberately produces less when the battery is full and the house needs little. In both cases the panels are fine; the energy simply had nowhere to go.
When to call an engineer
Contact us if you see any of these:
- Specific yield well below the estimate, after allowing for outages, export limits and monitoring gaps
- One string or MPPT input consistently lower than the others in the app
- A decline that continues after cleaning
- Repeated alarms or trips
- Visible damage: cracked glass, burnt marks, loose cables or a damaged structure
Do not open the inverter, combiner box or DC isolators yourself. Panel strings carry high DC voltage whenever the sun is up. Owner checks are limited to the app, the display, a look at the panels from a safe place, and cleaning per the instructions you were given. For a step-by-step fault guide, see why your solar system is producing less than expected.
What Solar Works does for a year-one review
Solar Works Pakistan's own engineering and technical staff handle after-sales service. When you register a complaint, our target is to send service personnel within 48 hours to begin diagnosis; the time to fix depends on the fault, parts and the manufacturer. For newer systems with monitoring, our team can often look at the data remotely first, subject to equipment capability.
During the first year, service is covered under the 1-year service warranty and the applicable project terms. After that, service and maintenance are chargeable when needed. Read how after-sales service works and use the annual maintenance checklist for the year ahead.
Get today's price or a free site survey
Send us your monitoring screenshots, your proposal and your last 12 bills. Our engineers will tell you whether your system is performing as expected and what, if anything, needs attention. If you are planning a new system or an expansion, we can survey your site too.
- WhatsApp or call: 0336 666 4321
- Email: info@solarworks.pk
- Head office: Main Boulevard, Sargodha Rd, Block F FDA City, Faisalabad
- Lahore branch: 2nd Floor, Jeff Heights, Gulberg, Lahore
- Hours: 9:00 AM to 6:00 PM, daily
- Service area: all of Punjab. See our Faisalabad and Lahore pages, or contact us.
Site surveys are normally free. Founded in 2021, Solar Works Pakistan has served 300+ customers, including 50+ industrial clients.
Frequently asked questions
How do I know if my solar system is producing what it should?
Divide your yearly generation by panel capacity in kW and compare it with your proposal's estimate and with the Punjab planning range of roughly 1,300 to 1,600 units per kW per year. Then look at the monthly pattern for any month that breaks the seasonal shape.
How much below the estimate is normal?
A few percent either way is usually down to weather and outages. A large gap, or one that keeps growing in clear months, deserves a check. Always allow for load-shedding, export limits and monitoring gaps before concluding that something is wrong.
Why did my system produce less in winter?
Winter days in Punjab are short, the sun is low, and fog and smog cut light further. Winter output is often around half of spring output. That is normal and is built into a yearly estimate.
Does load-shedding reduce my solar output?
On an on-grid system, yes. The inverter switches off when the grid is down for safety, so a year with heavy load-shedding produces fewer units. Hybrid systems can keep running from panels and battery.
Is a drop in the first year a sign of bad panels?
Not necessarily. All panels lose a little output in their first year as part of normal ageing, and the datasheet states the expected figure. A drop much larger than that, or one string much lower than others, should be checked.
Should I do the review before the first year ends?
Yes, if you can. Solar Works Pakistan's service warranty covers the first year under the applicable project terms, so raising an issue in month 11 or 12 keeps it within that period.