Solar Panel Configuration:
- See Solar Charger Mode: Shown below for the various models (PIP 1012 LV-MS, PIP 2424LV—MSD, SPF 3000TL, Hybrid LV5048, SPF 6000T, and an example solar panel specs) – The Hybrid LV5048 has 2 separate 80A MPPTs hence the 160A
- Fact, you cannot charge a 12V battery with 8V solar, likewise, a 24V battery with a 12V panel, likewise, a 48V battery with a 37V panel. An MPPT controller such as these require at least 2 x more Voc than the battery voltage. Example the PIP1012LV-MS, battery voltage = 12V x 2 = 24Voc (Vmpp would be around 25% of this value 24V panel (19.2Vmpp) , this is the actual voltage of the panel when its doing real work) – Notice the Min Solar Voltage in the specs? This is minimum voltage the MPPT will register – it will not charge a battery at this voltage!
- Example Question, I have a few 345W solar panels with specs shown on far Right, The Inverter Spec shows max Voc of 145V, so can I connect 3 of the 47.46V panels in series to make 3 x 47.46 = 142.38V ?
- Quick Answer: NO, not so fast! (But why, I am below 145V on my Inverter Specs ?)
- Fact: Solar Panel Voltage Increases with Colder temperatures and decreases with hotter temperatures. Ratings on the back of the panel are measured at 25 Dec C (77 F) . Most roofs hit temps of 158F in summer, this can reduce Solar Power output by as much as 25% (that 345W Panel is now only 276W), and its output voltage dropped almost by the same percentage. The opposite is true for cold winters day, remember that Voc of 142.38V above ?, well that could be exceeding that 145V limit on a 60 F day, and could be thrashing it by over 170V on a typical winter sunny day
- Fact. Panel voltage exceeding this Voc Voltage MPPT rating, simply causes the MPPT harvest of solar energy to FALL TO ZERO! Yes, on a perfect winters day, No Solar Juice going into your battery because of a simple oversight!
- “Voc” in summary, if I was living in the Caribbean, I may be tempted to try connecting 3 of these panels in series, living on the North American Continent, NO! Connect 2 in Series to be safe.
- Example Question: 2 x 345W panels in series on my PIP1012LV-MS (47.46 x 2 = 94.92) YES for Hawaii, No for the Mainland – its too close to the Max Voc of 102V, Answer: 2 x 345W panels in parallel. (1s2p)
- Rule of thumb for North America, make sure your Solar Array Voltage (Voc) will be at least 25% less than the Maximum Voc for the MPPT, Example MPPT Voc = 145V less 25% (divided by 1.25) = 116Voc
- Rule of thumb for 145Voc MPPT (116Voc), Max 2 Panels in series if Panel Voc is between 116V/2=58V & 116V/3=38V, Max 3 in series if Panel Voc is between 116V/3=38V & 116V/4=29V etc..
- Question: My MPPT is rated at 4500W how many panels can I connect: 4500W / panel wattage (345W in this example) = 15.6 Panels (you can over panel by 20%), add 20% = 18 panels, so 18 panels 2s9p config (2 panels in series with 9 matching strings in parallel) – this is absolute max, maybe you don’t want to stretch it by that extra 20% ? Then it would be 2s8p
- Solar MPPT Chargers are rated in either Watts or Amps, The Amps refers to the max current charging the MPPT can charge its 12V, 24V or 48V battery (Amps [80A]x Battery Voltage [24]=2000W, Amps [80A] x 48V battery = 4000W), Here is a trick – most 48V batteries charge at 57V so 80A x 57V = 4500W, same story for 24V batteries (26V or so) so 2250W in reality
