You've received several good suggestions that answer your questions. I'd like to suggest an alternative: Consider that your LCD is the limiting factor, rather than the panels. The PIC readily runs down below 3V. The LCD and the solar panels are expensive. Why not go down to 2 or 3 solar panels, and replace the alphanumeric LCD with a static LCD: http://www.ubasics.com/driving_static_lcds I use Digikey for samples, but they can be had very cheaply elsewhere, and are perfectly happy with 3V. Further, they draw significantly less current than the alphanumeric LCD - in the above project I was running at 32kHz (watch crystal) and drawing less than 1 mA at 3V (I'm surprised I didn't include the actual figure in the article, IIRC it was under 0.5mA). If you find the right solar panel (3-5V, 10-20mA) then you can use a single, very small, very cheap panel. You might need to use a 4 digit display, which would require a 40 pin PIC (also cheap if you choose a low-end pic) so you can have three digits for temperature, and one digit to indicate current display or mode. Of course, this may also make the user interface inconvenient depending on all the features/function you want to perform. You can also look around for 3V alphanumeric or graphic LCDs. Those without backlight do not consume much current. Good luck! -Adam On 3/28/07, Enrique Avalle wrote: > Dear Friends, > > I am NOT proficient in electronic matters, and so I am taking it slow and > easy, hobby like. Anyway, As I usually give my free time to a non profit > organization down over here (I am in Uruguay, South America) named PROFAUNA, > I proposed the addition of electronics / Pics to some of current Profauna's > projects. > > One very interesting project involves distribution of solar cooking ovens > among our country people. I designed a PIC 16f690 based system which > displays in a 2x16 LCD such information as cooking time, real time > temperature and also the mean temperature received among the whole cooking > lapse, a truly needed aid among solar cooking oven users. > > It works fine, being powered by 4 AA batteries. Problem is: I wanted a 100% > ecological / very non serviceable / autonomous solution (at least to show > off as an interesting achievement) so I bought 5 SOLAR PANELS (each one said > to give 1 volt / 400 mah). Previously, I measured my circuit, and it used > 5volts & less than 10mah. > > Problem is: I measure the solar panels (connected in series) and they give > me in eccess of 5volts under direct hard sun. I plug the panels to my system > and NOTHING HAPPENS. I plug the batteries and it works fine. > > I think it might be the necessary startup power (is there a PEAK ?) ... > > Any measurement / corrections / indications / advise and or ideas is > welcome. I am planning to buy a > > Artesyn Technologies DC/DC Converters Non-Isolated Point of Load > 15W 0.59-5.1V 3A Vertical Mount > http://www.artesyn.com/media/pdfs/ldo03c.pdf > > In order to place between the solar panels and my system. Is this a good > idea ? > > Regards, > > Enrique. > > P.d. I am placing my whole system (circuit design, software) in the public > domain, as I think it will be good for other people to work with and improve > upon. > > > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > -- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Moving in southeast Michigan? Buy my house: http://ubasics.com/house/ Interested in electronics? Check out the projects at http://ubasics.com Building your own house? Check out http://ubasics.com/home/ -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist