Skip to main content

How large a solar system can I plan with autarc?

Where autarc's limits are for large solar systems, batteries and commercial projects – in the simulation and in solar planning.

Written by Simon Heuschkel

autarc was built for residential buildings – from single-family homes to apartment buildings. You can also plan and simulate larger systems, for example on apartment buildings or commercial roofs. There are a few limits you should know about.

There is no size limit in the simulation. The limit is in solar planning: above a certain system size, the panels can no longer be displayed smoothly because solar planning runs on your computer.

Simulation: no size limit

The system simulation calculates solar yield, electricity consumption and battery regardless of system size. A 200 kWp solar system with a 500 kWh battery can be simulated just like a system on a single-family home, including the self-consumption rate, autarky level and profitability.

  • Several batteries: If you plan several batteries, the simulation treats them as one shared battery with the combined capacity. Charge and discharge power come from the product data.

  • Control scheme: By default the battery uses Maximise self-consumption: it stores solar power the building does not use itself and releases it as soon as generation is not enough. With Tariff arbitrage it also charges from the grid in the cheapest hours of a time-of-use tariff. This is also where you set Charge from grid up to and the Reserve state of charge.

  • Commercial projects: Use Create project > Create Commercial Project to create a project with the Project type Commercial. In the simulation the consumer is then called Business instead of Household.

Uploading a load profile for a business

The options under Usage pattern (e.g. Standard, All day, Home Office) are based on the standard load profile for households. For a business you should therefore upload a real load profile, e.g. the customer's meter data or data from the grid operator.

  1. In the simulation, click the Business (or Household) consumer.

  2. Under Usage pattern, select Custom load profile and then Upload CSV / Excel.

  3. No suitable file to hand? Download a template under Templates: (1-hour, 30-minute, 15-minute or 1-minute), paste in your values and upload the file.

  4. Drag the file into the field or click Browse files (CSV, XLSX or XLS, up to 25 MB). autarc detects the Sheet, Value column and Time resolution and checks the values.

  5. Under Yearly consumption, choose whether the file total applies or whether the profile is scaled to the annual consumption you entered, and click Apply profile.

Solar planning: the limit is your computer

Solar planning runs locally on your computer, and autarc displays every panel in 3D. How many panels you can plan smoothly therefore depends on how powerful your device is (processor, graphics card, memory). There is no fixed maximum number of panels.

With large systems, the planning first becomes slower and stutters when you move or rotate the view. Above a certain size, the panels can no longer be displayed properly. To plan large systems as smoothly as possible:

  • Powerful device: Use a current computer, ideally with a dedicated graphics card. Tablets and older laptops reach their limits sooner.

  • Close other programs: Close browser tabs and programs you don't need so more memory is free for the planning.

  • Plan without placing panels: If you don't need to place the panels individually, choose Configure by numbers. You then enter System size (kWp), Orientation (compass °) and Tilt (°) for each roof area and simulate straight away. Read more in Configuring a solar system by numbers.

We are working on performance improvements so that larger systems can also be planned smoothly. These are planned for the end of 2026.

What autarc does not cover yet for commercial systems

autarc comes from planning systems for residential buildings. Some features you would expect for large commercial systems are therefore not available yet:

  • Grid connection point and export limit: autarc does not model the grid connection point or its connection capacity, and the simulation does not curtail export. Check outside autarc whether the system fits the available grid connection capacity.

  • Load management and peak shaving: The battery is not used to cap load peaks, so autarc does not calculate savings from a lower peak load.

  • Demand charges: Commercial electricity tariffs with a demand (capacity) charge are not included in the profitability calculation. Only the unit rate and the standing charge count.

  • Exporting from the battery: The battery only discharges into the building, not into the grid.

  • Commercial standard load profiles: There are no standard load profiles for businesses. Upload the business's load profile instead (see above).

Frequently asked questions

Can I plan a 200 kWp system with a 500 kWh battery in autarc?

Yes, you can simulate a system like this without restrictions, ideally with the building's uploaded load profile. Whether you can also place the roughly 450 panels (with panels of about 450 Wp) individually in solar planning depends on your computer. If the planning becomes too slow, choose Configure by numbers. autarc does not currently model the grid connection point, peak shaving or demand charges.

From how many panels does solar planning become slow?

That depends on your device. As a guide: on a current MacBook Pro, a flat-roof system with around 560 panels (about 250 kWp) can still be planned, but the display becomes laggy at times. On older or less powerful devices this happens sooner. Much larger systems are better planned with Configure by numbers. Read how in Configuring a solar system by numbers.

Can I use a large battery to cap load peaks?

Not yet. The Reserve state of charge does hold energy back in the battery, but the simulation does not use it specifically against load peaks.

Related Articles
Did this answer your question?