Portable Solar Plan

Hi,

Roll your own is almost always cheaper.

MPPT is overkill on a 200 watt system that has nominally 12 volt panels. Look at the Grape 40 amp controller at Home Depot. (Don't get me wrong, the Victron is a heck of a good controller).

http://www.solarblvd.com/ has better prices than the Windy Nation kit (but does not include the frame).

For my detailed thoughts on solar surf here:

https://freecampsites.net/adding-solar/

pianotuna wrote:
Hi,

Roll your own is almost always cheaper.

MPPT is overkill on a 200 watt system that has nominally 12 volt panels. Look at the Grape 40 amp controller at Home Depot. (Don't get me wrong, the Victron is a heck of a good controller).

http://www.solarblvd.com/ has better prices than the Windy Nation kit (but does not include the frame).

For my detailed thoughts on solar surf here:

https://freecampsites.net/adding-solar/

Is it overkill if I will be adding 2 more panels eventually? I want the system to be expandable.

I'm looking forward to the outcome of this thread. I was thinking about something similar!

Hi Tizi,

Look at the cost per watt. The only time MPPT makes financial sense is when there is no room to add more panels. The Grape Controller can do 40 amps, so it may be likely that one would run out of roof space before running out of controller capacity. Plus the Grape is extremely programmable and temperature compensation.

Back when panels were $5.50 per watt MPPT made great sense. But with panels as low as 0.39 cents per watt that is no longer true.

Plus the Grape can do 24 volts to a 24 volt battery bank. All for $50.

Tizi wrote:

pianotuna wrote:
Hi,

Roll your own is almost always cheaper.

MPPT is overkill on a 200 watt system that has nominally 12 volt panels. Look at the Grape 40 amp controller at Home Depot. (Don't get me wrong, the Victron is a heck of a good controller).

http://www.solarblvd.com/ has better prices than the Windy Nation kit (but does not include the frame).

For my detailed thoughts on solar surf here:

https://freecampsites.net/adding-solar/

Is it overkill if I will be adding 2 more panels eventually? I want the system to be expandable.

The higher the voltage of the panel, the more benefit from an MPPT controller.

An PWM controller will only deliver the maximum amps the panel can drive (panel watts/panel voltage) while a MPPT control can deliver almost the full wattage of the panel. So a 100 watt 17V panel will only delivery a max of 5.9A with a PWM controller while a MPPT controller can deliver 7A (assuming charge voltage of 14.2V). With 2 panels and 10 hrs of daylight, that is 20A/hr or almost 1/2 of available power from a single battery. A 100 watt, 21V system will deliver the only 4.8A with a PWM, but the same 7A with a MPPT controller.

All that said, when I dived into solar, I went with a single 100 watt panel and PWM controller. It exceeds all of my power demands including charging two laptops, phones, several hours of fluorescent lights, and a night of running the furnace. I never really considered a portable panel because of fear of theft combined with no room to store them. Another advantage to the panels is on a full moon night, I get over 0.5A going to the battery. And as soon as the sky begins to lighten, the panels start putting into the battery. By just after sunrise, I'm already getting .75A.

OK, does that controller have a monitor or just by phone app? What else do I need? I like the panels on Amazon with the stands already attached (the stands if purchased separately are $50 each).

Controller - Grape 40 amp from Home Depot
Panels - Windy Nation with stands and fuses (2 x 100 watt)
Wiring - from panels to controller and controller to battery bank
Y Fitting (1 for each panel)
Fuse - from controller to battery?
Batteries - 2 Sams Club "Duracell" 6 volt AGM (220ah each)

I've got panels on the roof but I ended up buying a flexible panel on an Amazon lightning deal. It should be easy to store under the mattress. I'm thinking of putting it out on a clothes line that we usually have out or just lean it against something.

I'm going to use anderson connectors to plug it in to the camper so it will just be added in parallel with the other panels and go through my main charge controller.

I use a 45 watt PWM with 3 100 watt panels. the stands are made out of 3/4 inch pvc. There are only two reasons to consider MPPT, solar arrays over 400 watts or if you plan to wire the panels in series. I went with 100 watt panels because the physical size is easier to handle in and out the RV door.
Regardless of the CC efficiency the batteries determine how much current they will take. Also use a properly programmed battery monitoring system such as a Trimetric.
For best performance the CC must have remote temperature and battery voltage sensing and is why I choose the Morningstar TS-45.
For solar panel connectors I have used MC-4's without problems since 2012.

I come down on the other side of the PWM/MPPT debate. As kohldad said the higher thee panel voltage the more benefit you get from an MPPT controller. For limited area roofs like our campers, an MPPT controller can make 2 panels perform as if you had (almost) 3. I have the Renogy 100W panels (Vmp = 18.9V). Two panels with a PWM controller would give me 10.58 amps to the batteries. With an MPPT controller I'll get 14 amps, at 14.2v. With 3 panels, PWM = 15.87 amps, MPPT = 21.12 amps. With 4 panels, PWM = 21.16 amps, MPPT = 28.16 amps. (I have 4 panels)

The MPPT is more expensive, but to get the most current from the area I have I feel it's worth it.

YMMV

Hi Tizi,

Talk to MrWizard. He has the Grape controller. I do not but it is a nice unit imo.

Fuse as near the battery bank as possible.

DC Switch between the panels and the controller.

Tizi wrote:
OK, does that controller have a monitor or just by phone app? What else do I need? I like the panels on Amazon with the stands already attached (the stands if purchased separately are $50 each).

Controller - Grape 40 amp from Home Depot
Panels - Windy Nation with stands and fuses (2 x 100 watt)
Wiring - from panels to controller and controller to battery bank
Y Fitting (1 for each panel)
Fuse - from controller to battery?
Batteries - 2 Sams Club "Duracell" 6 volt AGM (220ah each)