# Generator calculator tool, is it accurate?



## jonnyirving (Jul 19, 2016)

Hello all,

I have recently build a web application that I am going to distribute for free to hopefully help with some of the problems people are having with their generator selection decisions. I have seen a few threads on this forum already that could of perhaps found this app helpful if they had had it at the time.

http://www.generator-calculator.com

I am basically looking for the experts in the areas to let me know how accurate and potentially useful they believe this is and especially any advice as to how this could be improved!

Does the final result make sense and look accurate?
Is this an oversimplification, if so what could I be missing?
What else could I add to be helpful (estimated cost to run per hour for e.g.)
General comments! 

The 'recommended' wattage is the highest starting wattage + the total running wattage of all other applications. This assumes that only one appliance will be started at once. The 'maximum' wattage is the wattage needed to start all appliances at once. 

Please note that I don't plan to make any money from this tool I just wanted to build something useful as a hobby and hopefully help a few people out in the process!

Regards, 

Jonny


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## Osviur (Sep 7, 2015)

*Genset selection*

Hi jonnyirving,

Congratulations for your work! it is really useful to help in a home power requirement generator selection.

I would like to recommend you, add a note about the kind of load to be served. In some cases, as a washer with an inverter motor driver, it is not critical, but in the case of a variable speed fan control furnace it is. It is not an easy problem to feed an entire house with "clean"energy enough to activate the advanced electronics contained inside the modern appliances, but at least alert to the potential gen set buyers, about the limitations found in generators with high harmonic distortion , so they can ask for an appropiate machine that will not generate surprises when connected to the internal house grid. 

Regards


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## exmar (Jun 29, 2015)

Ran it through the loads I have on during an outage and it hit the genset size I have exactly. Slick!


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## Markjames (Jul 23, 2016)

Osviur said:


> Hi jonnyirving,
> 
> Congratulations for your work! it is really useful to help in a home power requirement generator selection.
> 
> ...


agreed, having options for variable speed compressors, air handlers and other items would be useful. According to what I checked off I need close to 16,000 watts when running the items with 23,000 starting watts yet when I look online at average energy usage I am much lower. 

Most people sizing for a portable generator will know they make trade off decisions when on the genset- want to run the dryer? Turn off the hot water heater and AC.

What would be awesome in a calculator, although much more complicated, is to provide a 'basic', 'likely' and 'max' scenario - basic meaning no more than 1-2 larger loads at a time, likely being typical usage with a few tradeoffs and max being what you have now.


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## jonnyirving (Jul 19, 2016)

Osviur said:


> Hi jonnyirving,
> 
> Congratulations for your work! it is really useful to help in a home power requirement generator selection.
> 
> ...


Thanks for that insight Osviur,

That is not something that I was aware of and so this is very useful information. I have made a note of that as a feature to add. I am thinking that if the user adds a product that may be sensitive to high harmonic distortion that I could present them with some extra information somehow explaining the risks and special requirements they may have.

Thanks for your help. 

Jonny


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## jonnyirving (Jul 19, 2016)

Markjames said:


> agreed, having options for variable speed compressors, air handlers and other items would be useful. According to what I checked off I need close to 16,000 watts when running the items with 23,000 starting watts yet when I look online at average energy usage I am much lower.
> 
> Most people sizing for a portable generator will know they make trade off decisions when on the genset- want to run the dryer? Turn off the hot water heater and AC.
> 
> What would be awesome in a calculator, although much more complicated, is to provide a 'basic', 'likely' and 'max' scenario - basic meaning no more than 1-2 larger loads at a time, likely being typical usage with a few tradeoffs and max being what you have now.


Hey Markjames,

Yeah I love that idea about offering a range of scenarios that might be more likely to how the users will actually use their generators. I believe the maximum wattage is currently accurate as far as starting each appliance is concerned however this will be far to much for most peoples needs.

Some changes I am now considering:

Once all the items they wish to power are added to the list allowing the user to then turn appliance 'on' or 'off' with a switch type interface maybe. This would allow them to test certain scenarios based on the appliances they would like to run in parallel.
Adding a way of allowing users to get feedback on appliances with variable power usage.
Maybe offering the applications with two modes. One that works as now, adding all appliances up to find a total wattage and a second mode which allows the user to add the wattage of the generator they are considering buying or own already and then add appliances as the wattage counts down so they can get an idea of the capabilities.

Thanks for you insights!

Jonny


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## jonnyirving (Jul 19, 2016)

exmar said:


> Ran it through the loads I have on during an outage and it hit the genset size I have exactly. Slick!


Awesome, Thanks for doing that!

Jonny


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