> I see opinions that solar tracking doesn't need that much accuracy, and > also that they do. If anyone could throw out some numbers, that might > help For non focused arrays the loss of output for off normal sun angle is small for small angles - effectively 1.7% of Pmax per degree. I'd have thought it would be easy enough to build a solar tracker that calculates the sun rate and position based on the results from a few small sensors and uses it to initialise a tracking algorithm "for a rainy day". ____________ Sin(X) =3D 0.017 x X up to 33 degrees (amazingly!) The delta between adjacent degrees gets worse faster. Sin(X+1) - Sin(X) =3D 0.017 for X <=3D 20 degrees. SO you lose 1.7% of Pmax for every degree off centre. For focused arrays where the beam width is narrow this will not apply BUT it shows that shape of the lensed response is more important than the reduction in subtended area due to sun angle off normal. Russell ______________________ X degrees Sin(x) Sin(X)/X Delta Sin(X) per degree 1 0.0174524064 0.0174524064=09 2 0.0348994967 0.0174497484 0.0174470903 3 0.0523359562 0.0174453187 0.0174364595 4 0.0697564737 0.0174391184 0.0174205175 5 0.0871557427 0.0174311485 0.017399269 6 0.1045284633 0.0174214105 0.0173727205 7 0.1218693434 0.0174099062 0.0173408801 8 0.139173101 0.0173966376 0.0173037576 9 0.156434465 0.0173816072 0.0172613641 10 0.1736481777 0.0173648178 0.0172137126 11 0.1908089954 0.0173462723 0.0171608177 12 0.2079116908 0.0173259742 0.0171026954 13 0.2249510543 0.0173039273 0.0170393635 14 0.2419218956 0.0172801354 0.0169708413 15 0.2588190451 0.017254603 0.0168971495 16 0.2756373558 0.0172273347 0.0168183107 17 0.2923717047 0.0171983356 0.0167343489 18 0.3090169944 0.0171676108 0.0166452897 19 0.3255681545 0.017135166 0.0165511601 20 0.3420201433 0.0171010072 0.0164519889 21 0.3583679495 0.0170651405 0.0163478062 22 0.3746065934 0.0170275724 0.0162386439 23 0.3907311285 0.0169883099 0.0161245351 24 0.4067366431 0.0169473601 0.0160055146 25 0.4226182617 0.0169047305 0.0158816187 26 0.4383711468 0.0168604287 0.015752885 27 0.4539904997 0.016814463 0.015619353 28 0.4694715628 0.0167668415 0.015481063 29 0.4848096202 0.0167175731 0.0153380575 30 0.5 0.0166666667 0.0151903798 31 0.5150380749 0.0166141314 0.0150380749 32 0.5299192642 0.016559977 0.0148811893 33 0.544639035 0.0165042132 0.0147197708 34 0.5591929035 0.0164468501 0.0145538685 35 0.5735764364 0.0163878982 0.0143835329 36 0.5877852523 0.0163273681 0.0142088159 37 0.6018150232 0.0162652709 0.0140297709 38 0.6156614753 0.0162016178 0.0138464522 39 0.6293203911 0.0161364203 0.0136589157 40 0.6427876097 0.0160696902 0.0134672186 41 0.656059029 0.0160014397 0.0132714193 42 0.6691306064 0.0159316811 0.0130715774 43 0.6819983601 0.015860427 0.0128677537 44 0.6946583705 0.0157876902 0.0126600104 45 0.7071067812 0.015713484 0.0124484107 46 0.7193398003 0.0156378217 0.0122330192 47 0.7313537016 0.0155607171 0.0120139013 48 0.7431448255 0.0154821839 0.0117911239 49 0.7547095802 0.0154022363 0.0115647547 50 0.7660444431 0.0153208889 0.0113348629 51 0.7771459615 0.0152381561 0.0111015183 52 0.7880107536 0.015154053 0.0108647921 53 0.79863551 0.0150685945 0.0106247564 54 0.8090169944 0.0149817962 0.0103814843 55 0.8191520443 0.0148936735 0.0101350499 56 0.8290375726 0.0148042424 0.0098855283 57 0.8386705679 0.0147135187 0.0096329954 58 0.8480480962 0.0146215189 0.0093775282 59 0.8571673007 0.0145282593 0.0091192045 60 0.8660254038 0.0144337567 0.0088581031 61 0.8746197071 0.014338028 0.0085943034 62 0.8829475929 0.0142410902 0.0083278857 63 0.8910065242 0.0141429607 0.0080589313 64 0.8987940463 0.014043657 0.0077875221 65 0.906307787 0.0139431967 0.0075137407 66 0.9135454576 0.0138415978 0.0072376706 67 0.9205048535 0.0137388784 0.0069593958 68 0.9271838546 0.0136350567 0.0066790011 69 0.9335804265 0.0135301511 0.0063965719 70 0.9396926208 0.0134241803 0.0061121943 71 0.9455185756 0.013317163 0.0058259548 72 0.9510565163 0.0132091183 0.0055379407 73 0.956304756 0.0131000652 0.0052482397 74 0.9612616959 0.0129900229 0.00495694 75 0.9659258263 0.012879011 0.0046641304 76 0.9702957263 0.012767049 0.0043699 77 0.9743700648 0.0126541567 0.0040743385 78 0.9781476007 0.0125403539 0.0037775359 79 0.9816271834 0.0124256605 0.0034795827 80 0.984807753 0.0123100969 0.0031805696 81 0.9876883406 0.0121936832 0.0028805876 82 0.9902680687 0.0120764399 0.0025797281 83 0.9925461516 0.0119583874 0.0022780829 84 0.9945218954 0.0118395464 0.0019757437 85 0.9961946981 0.0117199376 0.0016728027 86 0.9975640503 0.011599582 0.0013693522 87 0.9986295348 0.0114785004 0.0010654845 88 0.999390827 0.0113567139 0.0007612923 89 0.9998476952 0.0112342438 0.0004568681 90 1 0.0111111111 0.0001523048 --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .