Start with the load and the grid
A solar panel on Nauvis is listed at 60 kW at full daylight, but its listed day-cycle average is 42 kW. The missing energy must come from storage when sunlight falls below consumption; multiplying the panel peak by a count does not establish continuous output. A normal accumulator stores up to 5 MJ and can charge or discharge at up to 300 kW.
These figures are community-maintained references, not measurements of your save. Confirm all panels, accumulators and consumers belong to the intended electrical network. Existing steam or another generator can mask a storage deficit; if you want to isolate a test, do so only after protecting the factory from an interruption. Do not remove a working backup merely because a calculated ratio looks sufficient.
- Record the version, location, active mods and equipment quality; inspect actual electrical demand across its normal peaks.
- Count only panels and accumulators connected to the intended network; note any other generators and storage already in it.
- Choose a constant test load or a conservative planning load, then calculate panel output and storage separately.
- Observe accumulator charge before and after a full cycle without assuming a short daytime sample represents night behavior.
- If energy falls to zero, find the first failing boundary before adding buildings; record one change and retest.
References: Factorio Wiki: Solar panel · Factorio Wiki: Accumulator · Factorio Wiki: Electric system
Worked planning budget: 1 MW around the clock
Suppose the isolated network's demand is exactly 1,000 kW continuously, there are no other losses, sources or consumers, and the storage starts charged. A panel's 42 kW day-cycle average yields 1,000 ÷ 42 = 23.81, rounded up to 24 panels. Their theoretical peak is 1,440 kW, while the ideal cycle average is 1,008 kW. Eight kilowatts of average headroom is small; an additional load or interrupted connection can change the result.
For normal equipment on Nauvis, the solar-panel reference lists about 0.84672 accumulators per panel at the 42 kW-per-panel steady-load design point. For 24 panels, 24 × 0.84672 = 20.32128, so round up to 21 accumulators. They can store 105 MJ when full and together have a nominal maximum discharge of 6.3 MW. Those limits serve different purposes: 105 MJ is stored energy, not a sustained 105 MW output. The 1 MW assumption is slightly below 24 × 42 kW, but this calculation does not simulate a particular save.
| Planning check | Illustrative calculation | Interpretation |
|---|---|---|
| Generation | 24 × 42 kW = 1,008 kW cycle average | 8 kW above the constant 1 MW example before any extra loads |
| Storage count | ceil(24 × 0.84672) = 21 | Round a building count up; assumes the referenced Nauvis model |
| Full stored energy | 21 × 5 MJ = 105 MJ | Capacity, not evidence the batteries are currently full |
| Discharge limit | 21 × 300 kW = 6,300 kW | Above the example's 1,000 kW load; stored energy is a separate constraint |
References: Factorio Wiki: Solar panel · Factorio Wiki: Accumulator · Factorio Wiki: Solar power math tutorial
Why older ratio advice can be slightly short
Some reference pages still quote 25 panels for 21 accumulators. The more detailed current solar-panel page and a player analysis of the 420-second Nauvis cycle give 0.84672 accumulators per panel for the stated normal-quality steady-load model. On that model, 25 panels require 21.168 accumulators before rounding, so 22 is the conservative whole-building count for a load at their full 42 kW-per-panel average.
This is a comparison of models, not proof that any specific 25-and-21 factory will fail: the actual load may be lower, other power sources may contribute, or another build may use different timing. The Wiki's solar-math page reports its own tests of ratios, but GamerWin has not reproduced them. Different planetary sunlight and day lengths invalidate transferring this Nauvis ratio unchanged.
References: Factorio Wiki: Solar panel · Factorio Wiki: Solar power math tutorial · Factorio Forums: Solar power ratios for planets and quality
Diagnose the first failed boundary
If panels appear productive in daylight but charge falls to zero each night, inspect both consumption over the whole cycle and charge at the start of dusk. A partly charged battery is not the same as a full 5 MJ battery. Persistent discharge despite no obvious missing cable may mean panel generation is inadequate for the actual load or there is not enough connected energy storage; both can occur together.
If charge remains but the electrical network is under-supplied, inspect network connection and output limits separately. A full accumulator on a different electrical network cannot supply the tested load. Factory demand may spike, so preserve a known backup while you inspect the electric-network graph.
| Observed symptom | First check | What to verify next |
|---|---|---|
| Panel or battery absent from the expected graph | Electric pole connections and network | Device appears on the intended network |
| Charge never recovers by late day | Generation versus the actual changing load | Record charge across the full cycle and check competing loads |
| Charge reaches zero before sunlight recovers | Usable stored energy and load during discharge | Check charged count and whether daytime surplus can refill it |
| Charge remains but demand is not met | Network and combined discharge capacity | Check the source's network and the actual load peak |
| Steam runs while checking solar | Other connected generation | Separate its contribution before attributing success to solar alone |
References: Factorio Wiki: Electric system · Factorio Wiki: Solar panel · Factorio Wiki: Accumulator
Keep a reproducible test record
Record a full game-time cycle, starting charge, ending charge and the load's range. If initial and final charges differ, average generation and actual consumption were not balanced during that interval; a single screenshot cannot establish a sustainable rate. Equal charge is not sufficient proof either: check electrical satisfaction, because a power-starved factory can consume less than its requested demand. Note backup generators and whether demand changed. Repeat after changing one factor, while retaining a safe recovery path.
Version / mods / planet / equipment quality:
Network and other generators:
Panels and accumulators connected:
Demand range and measurement interval (game-seconds):
Accumulator charge at start -> end:
First failed boundary:
One change and observed result:Before you play
- Confirm Nauvis, normal equipment, cycle assumptions and all connected generation.
- Separate 60 kW daylight output from 42 kW cycle-average panel output.
- Compare expected energy storage and instantaneous accumulator discharge independently.
- Record starting charge and variable load over a full cycle.
- Keep backup power until the actual grid has been checked.
Frequently asked questions
Will 24 panels and 21 accumulators power any 1 MW factory?
No. This is a theoretical constant-load Nauvis budget with normal equipment and stated cycle assumptions. Peaks, other consumers, an uncharged battery, disconnected devices, mods or another planet can invalidate it.
Does one 5 MJ accumulator deliver 5 MW?
No. MJ is stored energy; the normal accumulator's listed maximum discharge is 300 kW. Energy capacity and discharge power answer different questions.
Did GamerWin test this build in a save?
No. The numbers are source-based arithmetic and the diagnostic is a proposed reader procedure, not a measured gameplay result.
Sources & revision notes
Editorial revision: October 29, 2026; not a gameplay test date. The reference notes identify source limits and version differences.
- Factorio Wiki: Solar panel (Community)
Community-maintained reference checked October 29, 2026 for normal 60 kW daylight, 42 kW Nauvis average, planet differences and 0.84672 normal accumulator ratio. Not a GamerWin gameplay test.
- Factorio Wiki: Accumulator (Community)
Community-maintained reference checked October 29, 2026 for normal 5 MJ capacity and 300 kW maximum charge/discharge. Its older 21:25 approximation is not treated as exact for the 420-second model.
- Factorio Wiki: Solar power math tutorial (Community)
Community-maintained tutorial checked October 29, 2026 for the detailed 420-second calculation and its independently reported ratio tests. Page marked as a candidate for deletion; not a GamerWin test.
- Factorio Forums: Solar power ratios for planets and quality (Community)
Player forum analysis checked through search-index excerpts October 29, 2026; direct page access was restricted. Discusses the change from the old 416.67-second Nauvis cycle to 420 seconds and planet and quality differences. Its testing is that player's, not ours.
- Factorio Wiki: Electric system (Community)
Community-maintained reference checked October 29, 2026 for electrical networks and accumulator behavior.
- Factorio Friday Facts #449: 2.1 Stable (Official)
Developer announcement checked October 29, 2026 establishes 2.1 stable release context; it does not confirm a test of this guide.
Published a source-based Nauvis panel, energy-storage and discharge budget, including a documented warning on older ratio estimates. No tested save, observed outage or guaranteed factory throughput is claimed.
How we research and correct guidesNo affiliate links or paid placement. Commercial disclosure.