MPPT Sizing

[jonnydot]

Hi guy's new to solar and I wish to put 2 solar panels on the poptop of my 1976 vw kombi camper.I have found panels that will fit and are not overly heavy (Please see ebay link) Could someone please advise me as to what MPPT size I would need to run 2 of these panels and what would be the best way to join them together series or parallel ? I will be running an alternator charge and shore charge as well and at first 2 x 135 watt 12 volt lithium batteries. Many thanks for reading regards Jon ....... https://www.ebay.com.au/itm/350W-12V-Solar-Panel-Kit-With-Regulator-350-watt-Mono-Caravan-Camping-Charger/233494784677?ssPageName=STRK:MEBIDX:IT&_trksid=p2060353.m1438.l2649 EDIT:- I am in Australia but will be travelling to area's that get well below 0 degrees C

 

[Bubba1]

The link is for full kit with some type of charge controller. I would look for panels that don't come with controller so you can buy one that is compatible with your batteries. 700w of panels seems like a lot to me. What are you powering? If you will be in freezing climate you need to protect your batteries somehow.

 

[jonnydot]

The link is for full kit with some type of charge controller. I would look for panels that don't come with controller so you can buy one that is compatible with your batteries. 700w of panels seems like a lot to me. What are you powering? If you will be in freezing climate you need to protect your batteries somehow.

The controller that comes with the panels looks like a throw away item I will be getting something that has bluetooth and tune able to the batteries.I chose these panels for their footprint and weight I could not find any other brands that are the same or similar . I will be running a 240v fridge and most likely a 240v induction cooktop + tv, lights, charging tool batteries etc. The batteries will be protected via a heatmat and thermostat

 

[mikefitz]

The kit indicates a single panel size 1076 mm x 820 mm, this will not produce 350 watts. This panel is a 150 watt panel at best. Typically its around 165 watts per square meter of panel.
I suggest you find another source that provides correct information regarding the panels.

There is not a lot of room on your camper for panels so I can understand the panels in the link being attractive.

The MPPT controller I recommend is the Victron Smart range. For a 12v system , assuming you have over 350 watts of panel the 100/30 version will take up to 440 watts and the 100/50 up to 700 watts. The model numbers relate to the maximum panel input voltage, 100 volts,and the maximum current output into the battery 30A or 50A. Typical panels will have an OC voltage of around 22v for smaller panels and and large panels around 40 volts. Connect in series, two of the 40v panels and up to four 22v panels.

Mike

 

[jonnydot]

The kit indicates a single panel size 1076 mm x 820 mm, this will not produce 350 watts. This panel is a 150 watt panel at best. Typically its around 165 watts per square meter of panel.
I suggest you find another source that provides correct information regarding the panels.

There is not a lot of room on your camper for panels so I can understand the panels in the link being attractive.

The MPPT controller I recommend is the Victron Smart range. For a 12v system , assuming you have over 350 watts of panel the 100/30 version will take up to 440 watts and the 100/50 up to 700 watts. The model numbers relate to the maximum panel input voltage, 100 volts,and the maximum current output into the battery 30A or 50A. Typical panels will have an OC voltage of around 22v for smaller panels and and large panels around 40 volts. Connect in series, two of the 40v panels and up to four 22v panels.

Mike

Here is another same size 350 watt https://trailercamperaustralia.com.au/12v-350w-fixed-mono-crystalline-solar-panel-mountable-kit.html

 

[jonnydot]

here is another 350 watt panel that is only .0243m2 larger https://www.kogan.com/au/buy/toughl...charging-power-battery-350-watt-spm-gflat350/

 

[chrisski]

Typically its around 165 watts per square meter of panel.

here is another 350 watt panel that is only .0243m2 larger https://www.kogan.com/au/buy/toughl...charging-power-battery-350-watt-spm-gflat350/

You should be measuring panels by size for output. The panels are more or less the some output per square meter, with not a huge difference. I bought a high efficiency panel, and this was only a tenth of an inch smaller than the bigger panel.

There are many unscrupulous sellers making false claims. More so on E-Bay than other places I look.

When I bought my panels I used a reliable company, like Renogy to measure other panels. A 100 watt panel is 42 inches by 20 inches -or- 107 cm X 51 cm. If you see something really deviating from that, don't expect results much different than 100 watts per 42 inches by 20 inches -or- 107 cm X 51 cm

The exceptions to this only make output worst. Flexible panels are slightly large, and what is sometimes advertised as solar blankets or roll out panels are worst output that mentioned.

Any claims to the contrary will prove false.

=======

Can you confirm your battery bank? I think they're 135 AH batteries, not 135 watt.

 

[jonnydot]

You should be measuring panels by size for output. The panels are more or less the some output per square meter, with not a huge difference. I bought a high efficiency panel, and this was only a tenth of an inch smaller than the bigger panel.

There are many unscrupulous sellers making false claims. More so on E-Bay than other places I look.

When I bought my panels I used a reliable company, like Renogy to measure other panels. A 100 watt panel is 42 inches by 20 inches -or- 107 cm X 51 cm. If you see something really deviating from that, don't expect results much different than 100 watts per 42 inches by 20 inches -or- 107 cm X 51 cm

The exceptions to this only make output worst. Flexible panels are slightly large, and what is sometimes advertised as solar blankets or roll out panels are worst output that mentioned.

Any claims to the contrary will prove false.

=======

Can you confirm your battery bank? I think they're 135 AH batteries, not 135 watt.

135Ah sorry

 

[HRTKD]

here is another 350 watt panel that is only .0243m2 larger https://www.kogan.com/au/buy/toughl...charging-power-battery-350-watt-spm-gflat350/

Max Power : 350W
Open-circuit Voltage 22.3V
Short-circuit Current: 20.8A
Max Power Voltage: 18.4V
Max Power Current: 17.5A

Maximum Power Tolerance: ±3%
Max System Voltage: 1000V
Operating Temperature Min: -40°C
Operating Temperature Max: 85°C
Cell Tech: Mono-Si
Module Application Class: A
TUV Certification: Yes
Size:1070 x 820 x 30 mm (L x W x H)
Weight 9kg

How are they getting 350w out of that panel?

My 60 cell 320 watt panel measures 1676mm x 1008mm x 40mm and has Voc 40.8, Isc 10.028

 

[rickst29]

The controller that comes with the panels looks like a throw away item I will be getting something that has bluetooth and tune able to the batteries.I chose these panels for their footprint and weight I could not find any other brands that are the same or similar . I will be running a 240v fridge and most likely a 240v induction cooktop + tv, lights, charging tool batteries etc. The batteries will be protected via a heatmat and thermostat

Your induction Cooktop requires HUGE Amperage, you might need to back down (to propane). Size your instantaneous maximum load and Inverter first. Size your daily Kwh second, and your battery bank third. (BTW, batteries are not measured in Watts, they're measured in Ah.)

Only then consider your Solar possibilities (maybe with shingled "semi-flexible" panels, or panels which can be raised into a better angle for sunlight after stopping at a campground).
- - -
Meanwhile, to quantify this seller's fraudulent power claim: His "350 watt" panels are 1370 square inches in size. The "shingled" panels which I use, also built with highest-efficiency mono cells are rated at "100 watts" (my customers never actually get that much, due to on-the-roof mounting angles) and they're 945 square inches each. My panels also have less wiring between cells. Under perfect conditions his panels CAN'T POSSIBLY BE MORE THAN 150 WATTS, and they're probably in the 120-135 Watt range. I'd work with a more honest seller.

 

[jonnydot]

I ended up purchasing 2 x Canadian Solar KU Power high efficiency cells CS3K-325ms split panels (specs in link) . I got them from a local installer who purchased them for a job he is doing for a builder but the home owner wanted different panels so I got them for $70 each pretty sure one would call that a bargain lol and I know that they are a quantified panel https://www.canadiansolar.com/wp-co...Zrf8Gdad14sAx86tNZSDRbPBJgyMv6qAALJj2Ilr5Q8xI

 

[mikefitz]

That's a great deal. Good to see you obtained panels with a true output. Comparing the dimentions you can see why we were suggesting much of the advertising in the links you gave was fraudulent.
Have fun fitting to the van.

Mike

 

[jonnydot]

That's a great deal. Good to see you obtained panels with a true output. Comparing the dimentions you can see why we were suggesting much of the advertising in the links you gave was fraudulent.
Have fun fitting to the van.

Mike

Yes I can those rat bags should not be able to get away with that. I am going to send ebay a message about it all. I Have come up with an idea to make them swivel and elevate to match the best sun position .Hopefully I can bring that to a successful fruition