<span class="highlight">Solar</span> charging questions

Siringo
A 200w solar blanket will , most likely, have more output than a 100w unit and so it will try to discharge some of it's output into the 100 w panel while still being attached to the controller. Some panels/blanket have a LARGE diode in the output line to stop any back feeds, many do not. SO, it would be best to check the electrical setup each has. If using a 100w panel and a 200w panel connected in parallel to the controller the 200w, being higher voltage and amps output will almost negate the 100w. For best results the Panels/blankets connected in parallel should be of matched voltage and output ability so both feed similarly to the controller.
YES, a good quality MPPT controller, WiIL and DOES, provide more harvest of solar input and convert more of it to battery charge than a PWM, ie, on and off type of controller. I have three panels in parallel and read their input amps to an in vehicle MPPT charger. While charging, The solar amp input meter is always lower than the battery amp input meter reading because the MPPT unit, fast switches, and detects where the best panel output is, ie, the panel volts might be around16.7v and the 9amps BUT the battery is being charged at say 14v and receiving 11amps of charge at that same time.
Real not on paper,
I run my house 240v ac fridge on a 12v 1000w inverter system using two matched 250w panels in series, producing 65v or so. That energy which may get to 8 amps flow is used by the MPPT regulator to charge around 300AH of batteries. Because of the series connected panels and the higher voltage above battery voltage the MPPT unit can sometimes be producing 25-28 amps into the battery. When the regulator drops out of MPPT mode, ie, batteries close to charged, the difference of panel amps and battery charge amps is not much, 1 or 1.5 amps difference then. Most chargers have 3 or 4 modes of operation and switching of solar input so it varies according to the charge profile they use. for the type of battery used.
Most times I look at the monitor, the solar voltage is fairly high, ie, two panels in series, and the solar amps to battery charge amps is nearly always 4 times more amps than the solar amps because of the higher voltage the reg is receiving. MPPT makes good use of this ability. The regulator of course has to be able to withstand the full open circuit voltage of the panels to work this way. Make sure you buy an MPPT regulator which CAN handle higher voltages if EVER you decide to connect panels in series for your useage.

G'day Siringo

Yes you can hook up more than a single blanket.

No they don't need to be the same wattage, better if they are, the most important thing is they are of the same or very similar output voltage. Blocking diodes help but are not essential unless one panel has zero output, eg a blanket thrown over it.

The two types of regulators you are thinking of are MPPT ( maximum power point tracking) & PWM ( pulse width modulation). MPPT generally recognised as the better.

Regards

TrevorDavid

Thanks guys for the helpful comments.

i have a 175w panel a 120w panel ,i connect them with an anderson plug double adaptor
then plug it into the the solar plug in the camper trailer ,make sure they are unregulated when plugged into the van because you get the regs fighting the DC to DC charger in the van
an you end up with a waste of solar not going into the batteries
cheer mechpete

Personally I have never found a need for blocking diodes as long as the panels have a similar output voltage.

Paralleling panels on a MPPT also no problem, the MPPT looks at the max power point, ie it loads up the panels/s to find the max power and stabilises around it. Many MPPT will search for multiple max power points and use the highest one.