Announcement

Collapse
No announcement yet.

Math formula for calculation of solar power?

Collapse
X
  • Filter
  • Time
  • Show
Clear All
new posts

  • Math formula for calculation of solar power?

    Does anyone know if there are some mathematical formula for calculation of solar power? Or at least what parameters the electric energy depends on if produced by solar panel, like angle, days of sunny day, sunshine hour,latitude and longtitude,etc.?

  • #2
    All that you mention plus cell temperature, actual insolation, panel orientation (in regards to due south), haze, clouds and the characteristics of a particular panel manufacturers models.

    I have seen no detailed calculation - only the results.
    sigpic

    Comment


    • #3
      Wondering calculation for both off-grid and grid-tie? Are they same or not??

      Comment


      • #4
        The losses are substantially higher for off grid due to the use of batteries.

        The panel output is identical.
        sigpic

        Comment


        • #5
          Thanks Russ.
          I am curious what is the algorithm behind the solar power calculator on the web.Does any one have a clue?

          Comment


          • #6
            No idea Cris - I would like to have a better idea as well.

            If you use insolation for a location and stated panel efficiency the numbers come way off from what people seem to get.
            sigpic

            Comment


            • #7
              Possible..

              All that I can tell you is that this is possible, and the reason you don't see it posted around the internet is because people are greedy. (I work for a company that specializes in this kind of research)

              Comment


              • #8
                Originally posted by net_zero_energy View Post
                don't see it posted around the internet is because people are greedy.
                That is not greed my friend. People spends years and millions of dollars developing their product and methods. They do not give it away. Besides if you look around here I have detailed it out at 1000 times.
                MSEE, PE

                Comment


                • #9
                  Half full or half empty in my opinion. I'm sure there are a hundred ways to do this.

                  Comment


                  • #10
                    Originally posted by net_zero_energy View Post
                    All that I can tell you is that this is possible, and the reason you don't see it posted around the internet is because people are greedy. (I work for a company that specializes in this kind of research)
                    Oh! I see - a secret! A conspiracy! Those horrible people.

                    You may be a janitor for a company doing that kind of research - or maybe a secretary but you apparently know nothing but green blather.

                    We are not the kind of site that goes along with such trash talk.

                    Russ
                    sigpic

                    Comment


                    • #11
                      Originally posted by net_zero_energy
                      Russ you are quite the hypocrite.
                      What I said was not a personal attack on anyone, let alone anyone specific.
                      You are a moderator on this forum? That is concerning.
                      Be as concerned as you wish - your statement was silly and I simply pointed that out.

                      It is 'true green' to make wild unsupported statements and then try to shift the blame when you are called out.

                      Russ
                      sigpic

                      Comment


                      • #12
                        Originally posted by net_zero_energy View Post
                        Half full or half empty in my opinion. I'm sure there are a hundred ways to do this.
                        There are a few ways. even some you can find on the web from NASA, JPL, and Sandia National Labs is where most engineers develop their methods from. Point is people do not go to college for 4 to 12 years, spend another 4 or 5 years developing products and methods, have their work copyrighted and patented for nothing. It is a product or service like anything else you have to pay for. I can even sell you a program to do it for you, but I will be damned if I will give it away.
                        MSEE, PE

                        Comment


                        • #13
                          Various places have them and phone or email assistance.

                          Originally posted by crisliu View Post
                          Does anyone know if there are some mathematical formula for calculation of solar power? Or at least what parameters the electric energy depends on if produced by solar panel, like angle, days of sunny day, sunshine hour,latitude and longtitude,etc.?
                          I used the calculator in my Real Goods Solar Living Source Book, and also talked to their techs before ordering. I found out things have changed with some of the information I was given back in 1997. Like design for an 20% and not 50% battery draw down over 3 days or whatever the average cloudy days in a row you can expect. Shielding most inverters from phone lines and actually everywhere with thick overlapping and no leak gaps aluminum foil under the drywall. Over sizing the system enough for adding power suckers you didn't originally count on.
                          It was said there is more system loss with batteries than with a grid tie system. Mostly it is the opposite. The power companies make money off you, you need special inverters and switching, plus are vulnerable to their system outages. Usually the system is larger, too, and the payback time longer.
                          I like having independence. The 410 Ah L16S batteries I have are equipped with mandatory desulfators to double their life.
                          http://www.batterytechsolutions.com/
                          However, there are the nickel iron batteries that last 25 years for almost 4 times the cost. The losses occur in DC systems when there are long wire runs, so designing a power room the shortest distance from the panels, and the battery vented sealed area also very close. Batteries lose power when too cold.
                          My main system was designed for winter sun intake of 3000 watt hours per day, with use 2500 watt hours and battery bank to last at least 3 days without sun. 24VDC system. Basically, in an area of 5 hours daily winter sun and 3 days min. battery bank sizing, each of the 410 Ah batteries has one 75 watt panel on max efficient full tracking. I would have needed 12 if fixed of the reflective glass panel type they are, with a 1" hail rating at at least a 30* from horizontal angle.
                          My garage system has 4 of the same batteries with 74 watts of fixed textured surface unbreakable panels at the average sun angle. They lose about 10% from being fixed, and it is a 12VDC system. My maximum amps was slightly greater than 33% less than the charge controller rating, and the first charge controller burned out. The charge controller should be over 50% higher rating than max amps from the panels at the very minimum. Double is better.
                          If you are in, say a 2.5 hour of winter sun area, then you would need twice as many panels, and more batteries, too, for more cloudy days and for improving the ratio of summer performance.
                          The biggest way to save on the systems is to first make accurate calculations on power needs, winter sun, cloudy days---then determine exactly what you generally need, and shop around for the best deals, sales, etc. for panels, controllers, power centers, lightning arrestors, ground rods, fuzes, monitoring, inverters, batteries, mounting supplies, and wires you'll need. Read up very well, get what tools you'll need and save at least 50% on self installation if possible.
                          That is what I did, and the systems paid for themselves, including energy of manufacture, in 6 years. After that, the money saving went into paying off the already low mortgage from sweat equity. I am now mortgage and electric bill free.
                          The Earthship portion rarely needs wood stove heat, and I wish the whole complex was one large Earthship. The main thing is I have plenty of power for my heavy electric guitars and tube amps!!

                          Comment


                          • #14
                            Some unusual and questionable bits of information -

                            1) Real Goods Solar Living Source Book -

                            I actually prefer the Sharp calculator - several easy to change parameters to show the effect of panel orientation. http://sharpusa.cleanpowerestimator.com/sharpusa.htm

                            2) Shielding most inverters from phone lines and actually everywhere with thick overlapping and no leak gaps aluminum foil under the drywall.

                            Anything like wearing aluminum foil underwear/hats?

                            3) It was said there is more system loss with batteries than with a grid tie system.

                            You can believe this if you desire but telling it to others as truth is not nice. There are additional losses due to the charging/discharging of the batteries.

                            4) Battery charging - I'll defer to Sunking on this point

                            5) save at least 50% on self installation -

                            You intend to say save 50% of overall cost I believe. Highly unlikely and most people are not all that competent to do the job. If an installer tries this type of markup he won't be in business long.

                            6) A battery based system paid back in 6 years? A wonderful thing the internet - everyone has full freedom to make whatever claims they want - proof or accuracy not required. Science has no meaning at all to some people.

                            Russ
                            sigpic

                            Comment


                            • #15
                              Originally posted by Johnny Electriglide View Post
                              That is what I did, and the systems paid for themselves, including energy of manufacture, in 6 years.
                              You were doing fine until you told this Propaganda. There is no Economic or Environmental ROI on battery systems. Simple pencil and paper will blow that statement right out of the water. You might get away with that on other forums, but not here. Battery systems at best case are only 50% overall efficient, and that can only be achieved if you utilize every watt hour possible each and every day which is impossible. Anyone even th elay person will know that claim cannot be true because not even a grid tied system can pay itself back with using other peoples money and have them finance 60% of the system.

                              Your battery desulfator claim is laughable and there is not one peer reviewed third party documentation to back up that claim. IEEE has blown that statement out of the water. You cannot stop the natural formation of lead sulfate crystals from forming on the battery plates. Only proper usage and maintenance can slow the progression down, no marketing gimmicks can get around that. If there was one ounce of truth to your claim battery manufactures would be recommending it as it would greatly benefit them to keep battery warranty claims down to a minimum. All you have is the charge manufacture claims, and that will not cut it.
                              MSEE, PE

                              Comment

                              Working...
                              X