Solar Panel Calculator
Fast, accurate and free online paneli fotowoltaicznych calculator tool running directly in your browser.
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Photovoltaic panel calculator
Comprehensive analysis of the profitability of a photovoltaic installation with a 25-year forecast
Basic parameters
Financial parameters
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Fill in the parameters on the left and click the "Calculate" button to receive a detailed analysis of your future photovoltaic installation.
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Other tools you may find usefulPhotovoltaic panel calculator - calculate power, profitability and return (25 years)
Photovoltaics is great... until you overpay or choose the installation "by eye". This calculator helps you understand it in a human way: you enter the annual electricity consumption, a few roof parameters and costs, and you get specifics - how many panels, what power, how much energy you will produce in a year, what the savings will be, when the payback will take place and what the forecast looks like for 25 years (with the degradation of panels and the increase in electricity prices).
What exactly will this calculator calculate and why does it make sense
The biggest mistake with PV is looking only at the "installation power" (e.g. 6 kWp) without context: region, roof position, system losses, auto consumption and energy prices. Two installations with the same power may provide different savings in practice, and it is the savings (not the production itself) that determine the payback time.
PRO photovoltaic panel calculator combines four perspectives in one place:summary(power, production, area),finance(costs, subsidies, return and ROI),ecology(CO₂ and "equivalents") andtechnical details(direction, angle, inverter efficiency, losses, self-consumption and grid independence).
Main keyword: photovoltaic panel calculator
If you are looking for a "photovoltaic panel calculator", you usually want two things: to quickly select the power and to check whether it is profitable. Here you get both answers without pouring water - the result in panels, kWp and kWh, and specific PLN/year and years of payback.
Plus: there's no magic in the background. You see what influences the result (region, roof direction, angle, losses, inverter, auto consumption and optional battery), so it's easy to "click" through the scenarios and see where the greatest leverage is.
The most common long-tails that this calculator "solves"
In practice, people enter phrases in Google such as: "how to choose photovoltaics for consumption", "how many panels for a 4000 kWh house", "photovoltaics profitability in 2026", "PV calculator with a subsidy", "does energy storage make sense". These are questions of decision, not definition. This calculator is just for you: it allows you to compare options and find a healthy compromise.
If you want the result "in two minutes", enter only the annual consumption and electricity price. If you want a result "closer to life", start with roof parameters and losses, and finally add energy storage and a subsidy.
How to use the calculator step by step (without the technical stuff)
The best case scenario is simple: you start with the data you have on the invoice, and only then play with the "what ifs". It's a bit like a diet - first you count calories, and then you decide whether pizza is included.
- Enter the annual energy consumption (kWh/year).If you don't have it at hand - add up 12 months of invoices or take the annual value from eBOK. A typical household often consumes 3,000–5,000 kWh/year, but heat pumps and electric heating can significantly increase this.
- Set panel parameters and sunlight.The panel power is default (e.g. 450 W), and you can leave the sunlight around 1000 h/year, but it is better to adjust the region.
- Select the Polish region + the direction and angle of the roof.This is a quick way to "roughly" account for conditions. The south with a good roof will do the job, the north with a northern roof will require more power.
- Complete finances: energy price, installation cost and subsidy.Take the electricity price from the invoice (not from the headlines). Enter the installation cost in PLN/kW - it is then easy to compare companies' offers.
- Optional: Enable advanced parameters.System losses, inverter efficiency, annual degradation and increase in electricity prices - this makes a difference in the 25-year forecast.
- If you are thinking about the battery – enter the storage capacity.The calculator will show how self-consumption and independence from the network are growing. This is a great way to avoid buying batteries based on emotions.
What the results mean: panels, kWp, annual production and roof area
The most readable result is usually:how many panelsyou need andwhat powerin kWp. The calculator calculates energy production per panel based on effective sunlight (region + direction + angle + losses) and inverter efficiency, and then selects the number of panels so that the annual production "catches up" to your consumption - in a reasonable, mathematical way.
You also getestimated area(assumed typical module area). This is great because many people only discover when talking to the installer that "it won't fit on one roof slope." Here you see it right away and can test variants: greater panel power, a different layout, and sometimes simply different expectations.
Auto-consumption and independence from the grid - where the money really is
Energy production from PV is one thing. The second (and often more important) isauto consumption, i.e. how much energy you use on an ongoing basis. The more you use "at home", the less you buy online at the current price - and the faster the savings grow.
Without energy storage, auto-consumption is limited because a large part of production occurs in the afternoon. If the house is empty at this time, a lot of energy "escapes" into the grid. In turn, energy storage can increase self-consumption, but it costs money - so it is worth calculating it in numbers, not on advertising promises.
PV without batteries
The simplest and cheapest start. If you have daily consumption (working from home, air conditioning in summer, heat pump), auto consumption can be decent. This variant often gives the shortest payback at a reasonable installation cost.
PV + energy storage
An option for people who want to "keep" more energy at home and increase their independence from the grid. It makes sense where production and consumption overlap in time, or where energy security is a priority.
PV for expansion
First PV, then the battery. The calculator allows you to estimate the target storage capacity (in relation to daily consumption), so you can buy in stages and not freeze your budget at the start.
Costs, subsidies and investment return - how to read the "Finance" tab
Three things are important in finance:net cost(after subsidy),annual savingsandpayback period. The calculator breaks down the cost into PV installation (in PLN/kW) and possible energy storage (in PLN/kWh), and then subtracts the subsidy percentage. This makes it easy to get an offer from the installer and check whether "it works".
Annual savings are calculated taking into account auto consumption. This is important because in real life it is not the case that each kWh produced automatically disappears from the bill. If auto consumption is e.g. 35%, this part of production translates directly into "unpurchased electricity".
ROI in plain language
ROI in the calculator shows how much of the net cost you "recover" on an annual basis through savings. This isn't magic or a chart from a presentation - it's a quick comparative measure. If you are considering two offers, ROI helps you determine which one has the better cost/effect ratio.
Just remember one thing: ROI depends on the price of energy. If electricity becomes more expensive, real savings increase, so the ROI over time may look better.
25 Year Forecast - Why You Should Check It At Least Once
Even if you don't plan on staying in this house for a quarter of a century, the 25 Year Forecast does one brilliant thing: it shows the trend and sensitivity of the result. The degradation of panels (decrease in production year on year) and the increase in energy prices work in opposite directions - and the calculator arranges it into a clear series.
As a result, you see not only the "return after X years", but also how your accumulated savings grow and when the investment starts making real money.
Monthly production in Poland - why it is "sad" in winter
Photovoltaics in Poland is seasonal and this is normal. In summer, the installation can produce great numbers, but in winter - especially when it's cloudy - production drops. The calculator shows the monthly distribution, which is very practical: you can compare it with your own consumption (e.g. additional heating, heat pump, working from home) and see whether it is worth shifting some of the consumption to peak production hours.
Most common scenarios: who will find this calculator most useful
Farm 3000–6000 kWh
You want to choose the installation "according to the bills", not online advice. You will quickly check whether a smaller installation with better consumption or a larger one - with future needs in mind - is more profitable.
Heat pump / air conditioning
If you know that consumption will increase, the calculator helps you calculate "tomorrow", not just "today". This is important because an installation that is too small after expansion can be more frustrating than one that is too large at the start.
PV + energy storage
You are interested in self-consumption and independence from the grid. You enter the battery capacity and the calculator shows how it affects the result and what capacity makes sense in relation to daily consumption.
Parameters that most often change the result (and are worth testing)
If you want to get the most out of the calculator, play with the three sliders:roof direction, system losses i energy price. The direction and angle can "eat" a large percentage of production, losses tell how the system actually works in practice, and the energy price is a direct multiplier of savings.
- Check the "S" vs. "SE/SW" variant - often the difference is smaller than people fear.
- Set losses to 10%, 15% and 20% - see how the return changes over the years.
- Add a subsidy (e.g. 10-30%) and compare net cost and ROI.
- If you are thinking about the battery: test 0 kWh, then the "optimal" capacity, and finally a larger one - see where it stops being profitable.
A little cheat: what to enter if you don't have all the data
| Parameter | If you don't know | Where to get it better | Impact on the result |
|---|---|---|---|
| Annual consumption (kWh) | Take 12 months of invoices and add up | eBOK / annual invoice / counter | Very large |
| Energy price (PLN/kWh) | Enter the value from the bill (including distribution, if that's how you calculate it) | Invoice - items and rates | Very large |
| Installation cost (PLN/kW) | Set "medium" and compare offers | Quote from installer | Large |
| System losses (%) | 15% as a reasonable start | Contractor's specification / experience | Medium-large |
| Degradation (%/year) | 0.5% as a reasonable assumption | Panel data sheet | Medium (long term) |
| Energy price increase (%/year) | 3-8% as a testing range | Own conservative forecast | Large (in 25 years) |
FAQ - questions that are really asked before purchasing PV
Does the calculator take into account the region of Poland and differences in sunlight?
Yes. You can choose the region (northern/central/southern Poland), which affects the effective sunlight and final energy production. This will not replace an audit with local data, but it gives a reasonable picture of the differences and allows you to compare variants without going into complicated models.
Is the "how many panels" result calculated based on my consumption or "by eye"?
It is calculated based on your annual consumption and production per panel resulting from the settings (sunshine, losses, direction, angle and inverter efficiency). Thanks to this, the selection of panels is logical: first, the real yield from one panel is created, and only then is the number of modules selected.
Why aren't the savings equal to all PV production × energy price?
Because what matters is self-consumption. You use some of the energy "right away" at home and this is the simplest saving (you don't buy it from the grid). The rest depends on the billing method and your consumption profile. This calculator focuses on the part that directly translates into the bill, i.e. the energy used on site.
Does energy storage always accelerate the return on investment?
Not always. A warehouse usually increases self-consumption and independence from the network, but at the same time increases the investment cost. Therefore, it makes more sense to count several capacities (0 kWh, optimal, larger) and see where the additional cost ceases to translate into annual savings.
What does the "25-year forecast" mean and why does it include degradation?
The 25-year forecast shows how production will change in the following years (due to the natural degradation of panels) and how savings may increase if you assume an increase in energy prices. In practice, it's a "what will happen if the world is more or less as you predict it is today" model. It's a great comparison tool, even if you don't treat the numbers as oracles.
How do you interpret "roof area" and is it accurate?
This is an estimate based on the typical module area and number of panels. It is enough to catch the scale and filter out unrealistic configurations. The exact placement depends on the roof structure, windows, chimneys, safety margins and mounting system - but as a preliminary check of "will it even fit" it works very well.
Is this calculator suitable for comparing installers' offers?
Yes, and this is one of the best uses. Enter the price in PLN/kW, check the subsidy (if applicable), and then compare the payback time and annual savings. If two offers are similar in strength but dramatically different in cost, you'll see it quickly. If they differ in parameters (e.g. inverter efficiency), you can also easily recreate the scenario.
Summary without bullshit: why do you need this calculator
Because PV is not a purchase "like a kettle". This is a decision that will last for years. This calculator gives you a quick way to go from the general "it's probably worth it" to the specifics: how many panels, how much power, how much electricity, what savings and when the payback will occur. And if you like to be in control - advanced parameters will allow you to simulate realistic conditions, instead of counting on a perfect world.
Run the calculator and calculate your installation