| What it does | Free, accurate cycle and period predictor
| Independent calculator to check if a home battery pays for itself in your situation
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| Stage | Startup
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| Founded | 2026
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| Based in | Not given
| NL
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| Pricing model | Freemium
| Free
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| Pricing | All calculators and guides are free. Period Tools Pro (optional): $4.99/month or $19.99/year.
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| Key features | - Predicts next 6 periods
- Calculates ovulation day
- Identifies fertile window
- Private on-device tracking
- Cloud sync for Pro subscribers
- No signup required
| - Compares battery models from 23 brands on payback time and net result after 15 years
- Calculates with real hourly EPEX prices for dynamic energy contracts
- Processes the end of net metering from 1 January 2027
- Provides negative buying advice if purchase is not worthwhile
- No account or email required
- Generates 10-page PDF advice report with lowest prices from 11 shops
- Free 22-page PDF handbook about home batteries
- Analyzes consumption and solar generation hour by hour for full year
- Three scenarios: pessimistic, most likely and optimistic outcomes
- Updates prices from 11 online shops every morning automatically
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| What makes it different | - No data collection or server storage
- Uses standard medical calculation methods
- Honest about limitations and accuracy
- No aggressive marketing tactics
| - Truly independent: sells no batteries, has no arrangements with installers, publishes negative buying advice
- No personal data collection: zero signup required, immediate results without email
- Built from personal need: creator did his own calculations after a misleading sales pitch
- Comprehensive research: 384 example households analyzed in 26,112 calculations
- Shows all calculation assumptions: transparent methodology with public data sources
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| Community votes | 0 | 0 |
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| DR (Domain Rating by Ahrefs) | 15 ● no change since last check | 16 ● no change since last check |
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| Trust Flow (Majestic) | 20 | 18 |
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| Citation Flow (Majestic) | 9 | 24 |
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| Referring domains (Majestic) | 77 | 18 |
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Period Tools
Eerlijk over Thuisbatterijen