08-18-09, 02:32 PM | #1 |
harried homeowner
Join Date: Aug 2009
Location: Montana
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Solar MPPT
Solar arrays have a power curve with a maximum power point and the device that sets this point is called a Maximum Power Point Tracker. It's the electrical equivalent of a variable speed transmission - it's got nothing to do with pointing the array at the sun, strictly electrical charging.
Many places sell MPPTs, I've built some using a circuit idea from EDN, Dec 5, 2008. It's the cheapest, most foolproof I've found, but you have to be (or know) a EE who can help with component values. As time and work permits, I want to design an MPPT circuit board to handle charging 12V batteries at say 5-10 Amps and make the circuit boards available to the 'solar public'. 2 things - an MPPT is NOT a diverter (which shuts off charge power when it's had enough). this circuit is adaptable so, for instance, a 6V array can charge a 12V battery -it all depends on the charging IC. Befriend a geek, ask them. johnl |
08-18-09, 02:44 PM | #2 |
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First off, welcome to ER!
Woooo, very interesting. I was just reading and thinking about MPPT charge controllers the other day. Its great technology that can boost your panel output up to 15%. I'd love to see something for smaller applications. Do you have any circuit diagrams you'd be willing to share? |
08-18-09, 05:42 PM | #3 |
harried homeowner
Join Date: Aug 2009
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MPPT circuit
I tried to attach the EDN article as a .pdf <alas!> Here it is.
Solar-array controller needs no multiplier to maximize power - 12/5/2008 - EDN It is available on the EDN (Engr Design News) site; my design used the LT1316 from Linear Tech, but that part is user choice. That's the neat thing about the circuit, it's a P&O (perturb and observe) that only controls the normal feedback pin on a switch mode controller. You pick the controller and switch electronics from milliamps and low V up to mega-amps and big volts. This circuit does the equivalent of the kids' game - you're getting warmer, you're getting colder... and centers around the max power point! The designer is a regular circuit contributor and bright fellow. Gals to be here, good site. johnl |
Tags |
mppt, solar |
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