Slide Rule vs Solar Panel Calculator Plus
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Slide Rule
Simulates a mechanical analog computer for scientific and engineering calculations. Perform multiplication, division, roots, and trigonometric functions with a digital slide rule.
- Multiplication and division
- Square and cube roots
- Trigonometry functions
- Logarithm calculations
- Digital slide rule simulation
- Mechanical analog computer
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This app is a slide rule simulator. The slide rule (a.k.a. slipstick) is an mechanical analog computer which was formerly used for various scientific calculations, engineering design and surveying. It consists of three linear strips and a sliding cursor and is used for multiplication, division, square, cube, square root, cubic root, trigonometry, logarithm and so on. Please note that trigonometry and logarithm are not supported and the width of the scale is 1,000 pixels in this version.
Solar Panel Calculator Plus
Calculate custom off-grid solar home power systems. Determine the exact number of solar panels and battery capacity needed for your energy usage. Helps plan system size, inverter requirements, and battery bank specifications.
- Calculate solar panel requirements
- Determine battery capacity
- Calculate inverter size
- Estimate daily energy usage
- Plan days of autonomy
- Optimize battery life calculations
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Solar Panel Calculator Plus calculate custom Off-Grid Solar Home Power Systems. Use these handy calculator to help decide which system size is right for you. You can calculate the Exact Number of Solar Panels You Need For Your Usage Plus the Space you need. Also include Battery Capacity for your Home Power Systems. Daily energy use: Find the energy used in a day. Figure out how long each electronic device will be run in hours during a day. Multiply the wattage of each device by its run-time to get the energy in watt-hours per day. Add up all the watt-hour values to get a total for your home. Example: Light bulbs run for 5 hours a day. Computer runs for 2 hours a day. 100 x 5 + 300 x 2 = 1100 watt-hours. Inverter size: To determine the inverter size we must find the peak load or maximum wattage of your home. This is found by adding up the wattage of the appliances and devices that could be run at the same time. Include everything from microwaves and lights to computers and clocks. The sum will tell you which inverter size you need. Example: A room has two 60 watt light bulb and a 300 watt desktop computer. The inverter size is 60 x 2 + 300 = 420 watts. Multiply with 1.2 or 1.5 into a safe area. Days of autonomy: Now decide how many days worth of energy you want to store in your battery bank. Generally this is anywhere from two to five. Battery bank capacity: Example: You want the battery bank to last three days without recharging and that you use 5.0 kwh per day. As 5.0 x 3 x 2 = 30.0kwh, this is the energy we need from the batteries. Converting this to AH we have to divide by the voltage of your system. This can be 12, 24 or 48 for commercial application. If we choose to use 48V, the minimum AH capacity is then 30 000/48 = 625 AH. Now if you divide by your battery's rating you find the number of batteries you must use. The larger the system you have, the higher the voltage you should have. It is normal to match a 12 V battery bank to a 400 W power system. A 5 kW system would work most appropriately with a 48 V wiring system, in order to decrease current flow in the wires. Note: All calculations assume only a 50% discharge to your batteries to optimize battery life. Note: Colder temperatures have a negative effect on the capacity of your battery bank. If your battery bank is always indoors in a heated area then you don't have a problem. But if they're stored in an unheated area during the winter then you'll need to account for this. Solar Panel: The most typical solar panel size used for residential installations is 65 inches by 39 inches. And the wattage output range from 200 - 330 watts. *Thanks for your support, stay tune for more update to come
Screenshots
Verdict
The clearest difference is review sentiment: Slide Rule at 75% against Solar Panel Calculator Plus's 25%. Slide Rule also leads on price ($0.99 vs $2.99). Solar Panel Calculator Plus's advantage is rating (3.3 vs 1.0) and ratings volume (23 vs 1). On update cadence, ads, in-app purchases and monetization model there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
Slide Rule costs $0.99 and Solar Panel Calculator Plus $2.99 up front. Neither carries in-app purchases, so what you see is what you pay.
Solar Panel Calculator Plus holds the better App Store score, 3.3 against 1.0. That said, the two scores are not equally well evidenced: Solar Panel Calculator Plus has 23 ratings behind it against 1, so its average is the more settled of the two. Written reviews complicate that: 75% of Slide Rule's written reviews are positive against 25% of Solar Panel Calculator Plus's, so the app with the better star average is not the one people write more warmly about.
Slide Rule ships an update every 29 months, Solar Panel Calculator Plus every 47 months. The most recent releases landed on September 21, 2026 and August 22, 2026 respectively.
| Parameter | Slide Rule | Solar Panel Calculator Plus |
|---|---|---|
| Price | $0.99 — better | $2.99 |
| Rating | 1.0 (1 ratings) | 3.3 (23 ratings) — better |
| Positive reviews | 75.0% of reviews — better | 25.0% of reviews |
| Number of ratings | 1 | 23 — better |
| Update frequency | Every 29 months — better | Every 47 months |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Paid | Paid |
| Devices | iPhone, iPad | iPhone, iPad, iPod — better |
| Requires iOS | 17.0 | 12.0 — better |
| Further details — not scored | ||
| Size | 3 MB | 8 MB |
| Age rating | 4+ | 4+ |
| Developer | Masayuki Akamatsu | Nitrio |
Customer experience
Slide Rule
Solar Panel Calculator Plus
In-app purchases
Slide Rule
No in-app purchases
Solar Panel Calculator Plus
No in-app purchases
Questions
Is Slide Rule free?
Is Solar Panel Calculator Plus free?
Which has better reviews, Slide Rule or Solar Panel Calculator Plus?
Do Slide Rule or Solar Panel Calculator Plus have ads?
Which is updated more often, Slide Rule or Solar Panel Calculator Plus?
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