E, ovako treba... > Elektrika
Solarni paneli
zoki novus:
Bolje da zapecatite temu.....
marke:
Kapetane evo ti matematike:
Panel je opterecen sijalicom koja na 12v daje 20W.
Ako je tako znaci da joj je otpor 7,5ohma
Ako na mom testu pri otporu od 7,5ohma panel da 9,4V znaci da isporucuje struju od 1,253A
( U:R=I 9,4V:7,5ohma=1,253A ).
Znaci imamo napon od 9.4V i struju od 1,253A to znaci da je snaga panela pri ovom svetlu 11,778W
UxI=P ili 9.4V x 1.253A =11.77W.
Ako zelis da izmeris snagu panela optereti panel direktno otpornikom (sijalicom snage priblizne max. deklarisanoj snazi panela 120W) povezi ampermetar izmedju panela i sijalice a voltmetar na kontakte sijalice. Pomnozi tad taj napon i struju koju pokazuju oba instrumenta i videces kolika je snaga panela (pri datom osvetljaju).
Za tvoje primere nisam siguran sta si merio. Regulator potrosacima daje napon od 14.4v na izlazu jer mu je to i namena.
Ako je opterecenje vece od snage koju daje panel regulator trosi struju iz akumulatora i pegla napon na 14.4V.
Na kontaktima akumulatora napon varira zavisno od napona akumulatora i da li panel daje dovoljno struje da kad se napoje potrosaci preostane i za punjenje.
To sto napon punjenja ne prelazi pola volta vise od praznog akumulatora je normalno jer panel ne moze da puni sa toliko struje akumulator da bi mu napon podigao za vise od pola volta.
Kad se akumulator napuni i napon mu poraste i moze da dostigne max. 14,4v. Regulator tada prestaje da puni.
Kapetan:
--- Citat: Bane 26, 12, 2012, 15:30:20 posle podne ---seal the deal?
--- Kraj citata ---
solar sa digitrona za 30 evra sajkaca Habitat Srbija :)
marke znas da se bas u elektriku ne razumem, ali znam da citam po netu kako se meri snaga panela... i to sam i objasnio , najlakse ti je da meris struju kratkog spoja koja se UVEK deklarise na panelu i da vidis sta daje ...
ujedno il je panel koji su kupio odlican ili ti matematika ne valja , jer si pri losem svetlu dobio struju koja je veca nego maximalna struja koju taj panel daje u labaratorijskim uslovima ...
da te citiram :
"Ako na mom testu pri otporu od 7,5ohma panel da 9,4V znaci da isporucuje struju od 1,253A "
a proizvodjac kaze "DSP-20P 20W rated curent 1.11A", short cicuit (bez otpora, kratak spoj) 1,36A
Jebaga Stokholmski sindrom se duboko ukorenio u nas genom :(
Bane:
114
marke:
Pa sta te cudi rated curent (pri naponu od 18v) 1.11A a to je 19.8w snage koliko je panel deklarisan. Pri slabijem svetlu je dao 1.253A posto je napon na potrosacu pao na 9.4V ili samo 11.7W
Kratak spoj (Short circuit) je kad je napon izmedju 0V i 14.7v. To je zato sto je panel dizajniran kao izvor konstantne struje i daje svoju max struju vec na 80% napona i ta struja ne raste sve do kratkog spoja. (raste par procenata). To je zbog unutrasnjeg otpora samog panela.
20W:14.7V =1.36A.
Izmericemo sve na terenu zajedno kad ga postavim i povezem pa cemo da vidimo sta ume i moze. 114 114 114
P.S. Procitaj ovo:
The optimum operating point of a solar panel is typically about 90%+ of it's short circuit current and about 70% to 85% of its open circuit voltage. The more efficient a panel is the higher its optimum operating voltage is as a percentage of open circuit voltage.
The difference in dissipation in the panel between optimum operating point and short circuit is so close to the same as to be negligible. This is because a solar panel is close to being a constant current source - it is effectively designed to be run at very close to short circuit current.
The diagram below shows typical solar panel characteristics.
•The technical term for "sunshine level" is "insolation". The left hand diagram shows the result of varying light level or insolation - 1000 Watts per square metre is 'full sunlight". They do not say what the temperature is but this will be at constant temperature in ech case - usually 25 Celsius is used for comparison purposes.
•The right hand diagram shows the result of varying panel temperature when exposed to full sunlight.
In all cases it will be seen that the panel current is very close to constant on any chosen curves while the voltage is varies across its range. A voltage of 0 (at the left hand side) corresponds to a short circuit, and the maximum voltage (at the right hand side) corresponds to an open circuit.
As the panel is started to be loaded the voltage decreases and the current rapidly rises to very close to its short circuit value as more load is applied. For the large majority of its range he current is very close to its short circuit current.
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The diagram below shows the current-voltage relationship plus the power produced at different levels of insolation.
Look at the red curve for an example of the implications. As load is increased from open circuit (about V=44 volts, I= 0 Amps) to short circuit (V=0, I=5.2) the red power curve initially rises rapidly - from 0 Watts at 44 Volts to 150 Watts at 40 Volts, then peaks at about 36V/5.8A, then more slowly falls away as voltage is further reduced. The maximum value of the power curve is called the MPP (Maximum Power Point) and is the point at which maximum energy can be extracted from the panel. Note that at this point current has started to fall noticeably but not significantly from its short circuit value. I= 5.2A at short circuit and 4.8A at MPP. So, at MPP I =s 4.8/5.2 = 92% of I_short_circuit.
At MPP V = 36 V or 36/44 = 82% of its open circuit value. If this panel was opearted at short circuit the current would only be about 10% more than when it is run at it's MPP. As can be seen in the red./orange/blue curves, both the current and vootage at which MPP occurs vary as insolation is varied. Loading the panel so that MP laoding is achieved under all insolation levels is termed MPPT (Maximum Power Point Tracking - a whole new subject.)
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