How Many Units a 500 kW Solar Plant Generates: Per Day, Month and Year

A 500 kWp solar plant generates roughly 2,000 units a day, about 62,500 units a month and about 7.5 lakh units a year, on the north-India planning yield of 1,500 units per kWp per year used on this site. The honest range is 6.75 to 8.25 lakh units a year, depending on site, tilt, shading and soiling.

How is the generation of a 500 kW plant calculated?

The method is one line: plant capacity in kWp × specific yield (units per kWp per year) = annual units. Specific yield is the site's solar irradiation multiplied by the plant's performance ratio. The performance ratio already carries the losses: temperature, soiling, cable and inverter losses, shading and downtime. So you do not subtract those losses a second time from a yield figure.

Two points catch buyers out. First, the capacity in the formula is the DC module capacity in kWp. A "500 kW" plant may be quoted on the AC inverter rating, and the DC side is often larger. Ask which one the quotation means. Second, the specific yield must come from a stated source: a simulation for your coordinates, or a stated planning band. A quotation that gives units without the yield behind them cannot be checked.

The solar generation calculator on this site does exactly this multiplication. It takes plant size and site yield and returns annual, monthly and daily units, with a seasonal spread of plus or minus 15% around the monthly average.

What does a 500 kW plant generate per day, month and year?

The table below uses only the assumptions published on this site. The generation calculator accepts a yield of 1,350 to 1,650 units per kWp per year and defaults to 1,500, which it describes as the north-India planning band. The 500 kW solar plant cost page uses a slightly more conservative 120 units per kW per month, which is 1,440 a year. Both are shown, because a reader will meet both.

These are the site's planning assumptions, not a guarantee for your roof. Daily figures are the annual figure divided by 365, rounded. At the default yield, each kWp gives about 4.1 units a day, which is the "about 4 units a day" the calculator quotes for north India.

Region matters too. The 100 kW cost page puts yield at roughly 120 units per kW per month in the northern belt, about 135 in Rajasthan and Gujarat, and nearer 105 to 115 in the East and North East. For a 500 kW plant that moves the annual figure by lakhs of units, so the state matters.

How much does generation change through the year?

Not evenly. The calculator shows the strongest month about 15% above the monthly average and the weakest about 15% below. For a 500 kWp plant at the default yield, the average month is 62,500 units, the stronger month is about 71,875 and the weaker about 53,125.

In north India the weak months are December and January. Winter sun is lower, days are shorter and fog can remove whole mornings. Cooler modules are more efficient, but that gain is small next to the loss of irradiance. Spring and early summer give the strong months, although very high module temperatures in May and June trim the gain, and monsoon cloud brings a second dip.

The practical point for an owner: do not compare one month's meter reading with the average. Compare the same month year on year, or compare the plant against its simulated month. A plant that produced 53,000 units in January is not underperforming against a 62,500 average.

What reduces generation below the calculated figure?

The yield band assumes a well-designed, unshaded plant. These are the usual reasons a real plant falls short of it:

• Soiling. Dust costs several percent even with monthly cleaning, more in Delhi NCR. The cleaning interval is a contract term, not an afterthought.
• Shading. A parapet line or a water tank shadow at 4 pm can take out a string. On a 500 kW roof spread across several sheds, a shadow study before layout is cheaper than a loss for 25 years.
• Inverter clipping. An aggressive DC-to-AC ratio caps output at midday. It can be a sound design choice, but the yield must be calculated with it.
• Downtime nobody noticed. A failed string inverter in a plant with no monitoring can run for weeks. With 8 to 12 string inverters of 50 to 60 kW, as the cost page describes, one unit is about 10% of the plant.
• Grid outages. A grid-tied plant switches off when the grid fails, by design. Hours of outage are hours of lost generation, and they are not in a simulated yield unless someone put them there.

How does degradation change the numbers over the years?

Modules lose output slowly. The generation calculator's FAQ puts degradation at roughly half a percent a year after the first-year step, and the site's financial calculator uses 0.5% a year as its worked-example decline. Taking that as the site's assumption, and ignoring the first-year step, the default 7,50,000 units in year one becomes roughly 7,17,000 units by year ten (0.995 raised to the power of nine, applied to year one).

The actual curve is in the module manufacturer's warranty. Ask for the annual degradation rate and the guaranteed output at year 25, not only the day-one wattage. A lower-degradation module matters more to a 25-year asset than a small efficiency difference on the datasheet.

How to turn units into a decision

Units generated are not units saved. Only the share your plant load uses at the time of generation avoids a grid unit at your energy rate. Exported units are settled at the export rate under your state's rules. On the 500 kW cost page, the saving arithmetic is shown against the share of generation used on site, and payback moves with that share. Use the solar financial calculator once you have a yield figure from a study, and read the 500 kW page for the HT-side interconnection, which at this size is almost always the larger design question.

Before you accept any generation number, ask the bidder for five things: the irradiation source, the performance ratio assumed, the DC capacity, the degradation curve used, and whether the generation is guaranteed. If it is guaranteed, ask what the remedy is. If it is not, treat the number as an estimate.

How Secured Engineers helps

Secured Engineers designs solar plants in-house and files the approvals in-house: DISCOM net-metering, and CEIG where the connection needs it. MEPF and solar sit under one contract, so the HT interconnection, the DG interlock and the electrical room are one scope, not three. The company works from offices in Noida and Ludhiana and has delivered 535+ projects across 18+ states, with 89.77% repeat clients. Published C&I solar pricing is ₹24,000 to ₹32,000 per kW ex-GST on the solar EPC page. A generation estimate for your roof starts with a shadow-free area check and an irradiation simulation, not a rule of thumb.

To get a month-by-month generation estimate for your roof, message us on WhatsApp, call +91 70099 85817 or ask for a free quote. Send your latest electricity bill and a roof photograph, and we will tell you what a 500 kW plant would realistically produce there.