function updateSolpos() {
var lon = document.getElementById('lon').value;
var lat = document.getElementById('lat').value;
var tz = document.getElementById('timez').value;
var tilt = document.getElementById('tilt').value;
var aspect = document.getElementById('aspect').value;
var year = 2000;
document.getElementById('msgdiv').innerHTML="Calculating and Loading Solar Position...";
http.open("GET", solposurl + "?lon=" + lon + "&lat=" + lat + "&tz=" + tz + "&year=" + year + "&tilt=" + tilt + "&aspect=" + aspect, true);
http.onreadystatechange = handleHttpResponse_solpos;
http.send(null);
}