How to Read Your EV Solar Calculator Results: A Card-by-Card Guide

What You're Actually Looking At

VoltSun's EV solar calculator gives you eight data cards the moment you enter your address and select your car. Each card answers a specific question about your solar installation — no formulas, no spreadsheets. This guide walks through every card and every progress bar so you can read your results at a glance and understand what they mean for your home.

Sun-Powered Miles

This is the headline number: how many kilometers you could drive on solar-generated electricity in a year. It combines your EV's real-world consumption, the solar output for your exact location, and the system size you configured.

The progress bar shows what share of your total annual driving distance would be covered by solar panels. A bar at 80% means solar powers 80% of your yearly mileage — the remaining 20% would still come from the grid.

A realistic target for most European addresses is 60–90% solar coverage for EV charging, depending on local sun hours and how far you drive.

Annual Savings

How much money you avoid spending on electricity each year by charging your EV from solar instead of the grid. The figure uses real electricity tariffs for your region and your car's average energy consumption.

The progress bar represents savings as a share of your total annual EV charging cost without solar. A bar at 70% means solar eliminates 70% of what you'd otherwise pay at the grid rate.

This number is the annual income side of your solar investment — compare it directly against installer quotes to get an instant sense of how quickly the system pays for itself.

Grid vs Solar (Bar Chart)

This horizontal bar chart compares energy sources across the year. The amber bar is the kilowatt-hours your solar panels supply; the opposing bar is what still comes from the grid.

Read it left to right: the longer the amber bar, the less grid dependency. In summer the amber bar typically dominates; in winter it shrinks as solar kWh production drops with shorter days. If you're considering a home battery, this chart shows exactly how much excess daytime solar you'd need to store overnight to cut the grid bar further.

CO2 Saved

The annual CO2 emissions you avoid by charging from solar instead of grid electricity. Grid power in most European countries still carries 200–400 g of CO2 per kWh, so displacing it with solar has a real climate impact.

The progress bar shows your CO2 reduction as a fraction of the emissions your EV would produce if charged 100% from the grid. A full bar means zero-emission driving — your solar covers all your charging needs.

CO2 savings solar panels deliver are also useful context for sustainability goals, green mortgage applications, or carbon offset comparisons.

Estimated Panel Count

The minimum number of 400W monocrystalline panels needed to produce enough electricity to cover your annual EV charging. The figure accounts for your local peak sun hours (from PVGIS or NASA POWER), inverter losses, temperature derating, and soiling — the real-world factors that reduce output from the nameplate wattage.

The progress bar reflects how close this count is to filling a typical residential roof (roughly 30 m²). A bar at 50% means you need about half a standard roof's worth of panels — well within reach for most homes.

If the number looks large, check the Monthly Yield chart next. A summer-heavy location can still deliver an excellent solar energy ROI with fewer panels than you'd expect.

Monthly Yield (Bar Chart)

Twelve amber bars, one per month. Each bar shows the estimated solar energy output in kWh for that month at your specific address.

The height variation tells the story of your local climate: summer months peak high, winter months sit low. The brightest bar is your best production month — usually June or July in central Europe. Hover over any bar to see the exact kWh figure for that month.

This chart is especially useful for battery sizing decisions. If your peak month produces three times more than your average month, a home battery may only capture a fraction of summer surplus — context that helps you avoid over-investing in storage capacity.

Full EV Charges

A normalized view of your annual solar output: how many complete full-battery charges from 0% to 100% you could complete in a year using only solar electricity.

The progress bar measures this against a baseline of 52 full charges — one per week. A bar at 80% means your solar covers 80% of a hypothetical weekly full-charge cycle. In practice, most EV drivers charge partially and more frequently, so the real-world coverage is usually higher than this figure suggests.

Use it as a gut-check: if the number of full EV charges from solar exceeds the number of times you'd realistically charge from nearly empty, your system is more than sufficient for your driving habits.

Payback Estimate

Three numbers on one card:

• Install cost — the estimated system price at current market rates for your panel count and region
• Annual savings — identical to the Annual Savings card above
• 25-year profit — what you net after subtracting the install cost from 25 years of accumulated annual savings

The headline figure is the solar panel payback period in years: how long until cumulative savings equal the upfront investment. The industry average for residential solar in Europe is 7–11 years; anything under 8 years is a strong result.

The progress bar shows how early your payback falls within a 25-year panel lifespan. A bar at 64% means payback at year 9 — leaving 16 years of pure profit. The higher the bar, the better your solar energy ROI.

The 25-year profit assumes flat electricity prices. Grid prices across Europe have risen 4–6% per year over the last decade, so the real return is typically considerably higher than the conservative estimate shown.

Reading All Eight Cards Together

Step back and look at all the progress bars as a set — they tell a coherent story:

• High sun-powered miles + high annual savings + short payback → strong solar case for EV charging, move quickly
• Low panel count + high monthly yield → excellent location sun, even a compact system pays well
• High CO2 saved + low full charges → high-mileage driver; a larger system or battery storage would improve coverage further

No single card tells the full story. The dashboard is designed to show both the environmental and financial picture of solar EV charging together, so you can make a confident decision before you ever call an installer.