About creating a Solar energy calculator

NilaNila Solar Expert Posts: 173 ✭✭
Hi All,

Whenever users ask a question,

most of the time mods/admins here calculate all the voltages/amperes/drops,etc manually .

I believe making a one page calculator for all the solar related stuff can be very good, Making the work of manual calculations easy.
I wish to have a simple one page which can like calculate wiring sizes , calculate loads/ suggest the inverter/system voltage / battery and even suggest CC's ,etc


It would be very cool if some of the experts here offer a hand on the calculations,etc and list the features to include.
I know the basics and I own a web dev firm so I can volunteer one of my team/few devs to help create this calculator., I can also get this up on a website for everyone to use.

One feature I would have is to create a special URL for every calculation so that it can be easily posted to the forum and others can tinker with the values and post back what they come up with.

Let me know if i make sense or do you think it is better to do it manually and is not worth the effort?

Comments

  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: About creating a Solar energy calculator

    It would be a really big 'page'.

    When you start sizing you use "ballpark" figures and "rules-of-thumb". Then you have to get more specific once the basics are set.

    You have a range of options in batteries, panels, controllers, inverters. All of which have slightly different specifications which require adjustments to the other choices.

    Meanwhile the "operating margins" go up or down according to choices made on equipment. Some of the adjustments made are intuitive. A lot of "you could do this if you also do that or allow something else".

    Simple really doesn't enter in to it because each and every system is specific to the application.

    Just my POV on it. Others' opinions may vary.
  • NorthGuyNorthGuy Solar Expert Posts: 1,925 ✭✭
    Re: About creating a Solar energy calculator
    Simple really doesn't enter in to it because each and every system is specific to the application.

    I agree. There are solar calculators on the Web. Six or seven years ago I usead such a calculator and the numbers that I got were so bad that I made a conclusion that solar will not work for me. That was totally wrong. I'm getting ready to go off-grid now.
  • NilaNila Solar Expert Posts: 173 ✭✭
    Re: About creating a Solar energy calculator

    Actually we are not going to suggest a brand /model specifically.

    I understand every system is unique .. but some maths i see here are like repeating almost every day.

    Lets say someone has a load of xx at night .. and yy at day..
    Now tell him the total watts of panel/ amps of battery you require.

    and suggest him some general stuff like system voltage/size of inverter and wires,etc
    I think its not going to be simple or be all solution..

    You can also use that to get the requirements from the user/ and suggest him a system based on that etc.
    Also easy to have them in a simple page than looking at different calculators everywhere.
  • nielniel Solar Expert Posts: 10,311 ✭✭✭✭
    Re: About creating a Solar energy calculator

    no, easy fill in the blanks 1 page thing for this even though some aspects repeat often. a bit of knowledge and understanding of each area addressed along with other possible aspects, scenarios, and even efficiencies. if it was all that easy do you think we'd have this big of a forum going?

    i do admit that there was an attempt long ago by a member, who is no longer here on the forum, with a large multi-page fill in the blank xls type thing, but i never tried it. i did download it, but i couldn't even tell you if i still have it on the pc or which pc it was on. the member's name was bad apple.
  • BB.BB. Super Moderators, Administrators Posts: 29,509 admin
    Re: About creating a Solar energy calculator

    I think this is the spread sheet that Niel mentioned (in this thread):

    Backwards requirements calculator?


    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • nielniel Solar Expert Posts: 10,311 ✭✭✭✭
    Re: About creating a Solar energy calculator

    that's the one bill and thanks for digging that up. if anybody tries it out you are encouraged to give your feedback on it.
  • BB.BB. Super Moderators, Administrators Posts: 29,509 admin
    Re: About creating a Solar energy calculator

    I have a bit of time to give my two cents on the subject (been busy working around the house).

    For me, it is much more important for folks to understand their loads and requirements first. And no spread sheet/answer everything web site can do that. Everything is up for grabs at that point.

    And the "simple" equations that we use to estimate battery bank and solar array sizing all from from those initial estimates of power usage. And, are almost an "after thought" to the design process (input the numbers, turn the crank, out pops the results).

    I have tried a few of those websites/spread sheets over the years, and I usually become very quickly confused about their assumptions and "fudge factors" used. And, in the end, I have very little insight to the actual system design and what is driving the sizing/costs of the hardware.

    For example, the "simple" assumption for sizing a solar array is:

    Watt*Hours of load per day * 1/0.52 system derating * 1/ number of hours of noon-time sun per day = Solar Array size

    But, there is also sizing the solar array to battery bank size... We use 5% to 13% rate of charge:

    Battery AH size * charging voltage * 1/0.77 panel+controller derating * Rate of Charge (0.05 to 0.13 typical) = array size

    The equations are "simple"--It the information fed into them that matters... Battery bank can drive a larger solar array. Rate of charge choice affects array size. And why did somebody "pick" that battery bank (surge loads, # of days without sun/power, flooded cell vs agm, etc.).

    And what about those fudge factors. Why 0.52... Could be higher (more efficient) with AGM. Or why 4 hours of sun vs 1.8 or 5.2 hours of sun for array sizing.

    It is those "little questions" that usually drive the entire design cycle. And are very important towards sizing/designing a system that will work well for the end user/customer.

    And by having the formulas front and center--It highlights the previous design choices---And perhaps forces some thoughts about the initial decisions. Perhaps don't need as much power (use laptops/smaller computers vs larger desktop computers), only 2 days of storage and use a generator a bit more often (4x daily loads vs 6x day loads--a much smaller battery bank, less initial costs, less maintenance and distilled water, and less battery bank to replace 5-7 years down the road--or sooner if there was a major Oops somewhere).

    At this point, I have been hand typing the equations and using the Windows calculator. With some minor time savers (I do the 5-10-13% equation in order--So the 10% is simply 2x the 5%, and the 13% is 1.3x the 10%, etc.).

    There are enough variations in the questions that they are not all the same (some people have a battery limit, others limited by the amount of solar array they can install). Some folks want to size their system to the loads. Others want to size the loads to the system.

    So, there are variations of the formating of the equations that would be confusing (I think) if this was attempted with spread sheet that attempted to be all things to all people.

    On the other hand, I highly recommend that people take the equations they see and spread sheet them--Now that they know what the mean and what assumptions were made in the parameters. It certainly saves a lot of typing/calculations.

    However, have to be sure the spread sheet is correct too... More than a few companies have been damaged by spread sheets with incorrect equations/assumptions.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: About creating a Solar energy calculator

    Also a lot of people not only want to know what to do, but why they should do it.

    I could probably create a step-by-step for basic system planning, but people might consider that the start and finish of it. We already have trouble getting across the idea that the rules-of-thumb and ballpark figures are just a starting point, not a finished system. :blush:
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