solar panels

[yycwrangler]

HI Guys

As we turn the corner on winter, I'm looking to install solar on my cargo trailer (6X12). I want o bounce my idea off you guys as I know many of you have done solar already and I'd appreciate any feedback.
I'm looking at buying a 100. LIPO4 100ah battery. Yes I could buy the deep cycle but felt it's time to move into the 19th century lol. It is also lighter and can be discharged pretty much down to 0. I'm going to have a small charger for when I park at a campsite with power but I want to dry camp more. Hence the solar. I'm definitely purchasing a mppt as I understand they are much more efficient a controller than the PWM controller.

Questions - is monocrystalline the best bang for your buck and would 100watt solar be enough to charge the above battery in a good day of sun or should I buy several 100 watt panels or a 2-300 watt single panel. I also see there is flexible panels but I feel that there should be some airflow underneath a panel which these flexible panels would not allow. So I'm looking at solid panels on angle brackets screwed to the cross members of the trailer giving me a space under the panels. Thoughts on size of MPPT for my job?

Again any feedback you can give would be greatly appreciated. Even some good web pages explaining solar would be awesome

Cheers
Al in Calgary

[tony.latham]

nd would 100watt solar be enough to charge the above battery in a good day of sun or...

When the sun hits you, you'll get about 4-6 amps per hour from a 100-watt panel. So to answer your question, it depends on how many amps you pull from the battery and how long you are in the sun.

You also mention flexible panels. Most of them are junk --those made from PET plastic. I've got a Renogy made from ETFE that is a high-quality panel. Renogy (and in my experience) says you don't need a gap.



That may not be true with all flexibles.

Tony

[Philip]

I used Renogy flex panels on my first build. I used VHB tape. I left gaps in the corners for air flow under the panels. The gaps were not into direct air flow. They were on the side on the panels.

Find the charging rate the battery needs. If higher voltage is what it likes you can use multi panels and wire them or higher voltage for a faster recharge rate.

[tony.latham]

Find the charging rate the battery needs.

But isn't that what the charge controller does?





Tony

[mtbikernate]

Find the charging rate the battery needs.

But isn't that what the charge controller does?

I think what he's referring to is knowing your rate of discharge based on your use of that electricity, which will give you an indication about how much you need to feed back into the system.

I have a 100ah LiFePO4 battery and I've currently got about 240w of solar. I can run my trailer for a weekend without needing any charging at all, learned through some experimentation.

My trailer came with a small 40w Zamp panel (with its own PWM charge controller on it) and the original AGM battery (I forget the size of that). When I added the fridge and the LiPo, I realized that the little 40W panel would only be good for extending my time before the battery died, so I added 200w of rigid panels. That's enough for me to get my battery topped up before lunch with good morning sun. I haven't pushed things in a shady locations or cloudy conditions yet, but part of my logic for choosing more solar than minimally necessary is the assumption that I'm not always going to have ideal sun exposure. The way I have things hooked up, I can run all 240w of solar at once. Currently all panels are rigged to be used on the ground, but I'm currently working on rooftop mounts and wiring for the 2x 100w rigid panels so I can charge while driving (which means I can keep my battery topped up while running the fridge to keep food on long road trips where I'm not going to be able to lay out the panels on the ground and I may or may not have a spot to plug in when I stop for the night). I could easily upgrade the 40w panel to something bigger (with a built-in charge controller, as the plug it attaches to bypasses the Renogy MPPT).

[bdosborn]

I'm definitely purchasing a mppt as I understand they are much more efficient a controller than the PWM controller.

Questions - is monocrystalline the best bang for your buck

MPPT will get you around 10-15% more energy in cold weather, but not much more than a PWM when it's hot. I like PWM controllers for small PV panels, you can use the money you save to buy more solar panel. BUT, you'll need MPPT if you go with a higher voltage panel, show us which panel you like and we can point you towards a controller type.

Monocrystalline panels are more efficient, which means they will be a bit smaller than a polycrystalline panels of the same wattage. Otherwise, watts is watts and they both perform the same in different lighting situations.

Bruce