Solar Mayto

(System Design & Installation by by Sun Dog Solar Services)


Solar Photovoltaics at Rancho Sol y Mar:

Our system at Rancho Sol y Mar is a modest one (2.4KW array, 12-15KW daily), however due to the abundant sun here, we’re able to make a go of it with approximately 50% less equipment than a comparable system in much of the US or Canada would require.  As a visitor to Rancho Sol y Mar you are welcome to tour the facility, ask lots of questions, and consider how Solar Photovoltaics might fit into your own life style.

For those of you considering a move to Mexico, or who already live here and wish to reduce your carbon footprint, Sun Dog Solar owner Dan Gair’s design and system design, installation, and consulting services are now available. (

System Stat’s and considerations:

Main Components:

Array: (12) 200w Suntech Polychrystaline Panels

Charge Controller: Outback Flexmax 80

Inverter: Outback 3600w pure sine wave

Batteries: 48v (16 Trojan L-16, 6v, 420 amp/hour batteries in two 48v series strings )

Balance of system:

Midnight Solar Combiner Box

Outback Flexmax AC + DC load Centers w/ “Mate” monitoring system.

Trimetric Metering/Lightening Protection

BD-2 Desulphator

System Design Consideration:

The principal design behind our system was driven by several factors. As always cost was probably the biggest limiter, but also just getting the equipment here to rural Mexico was a  serious consideration. In the end, we decided to build a system that would support a half dozen campers drawing up to 2 KW each per day plus a bit extra for communal usage like a couple of washing machines. We considered this adequate since we live quite comfortably in our own off grid house on the property with a 7ft cubic frig, 10kg capacity washing machine, lights, fans, computer and other charging, etc with a .6KW system that produces about 4KW per day. When we’re running  lean we can get by comfortably on closer to 2KW per day so we figured that we could grow the campground up to a dozen sites or so before needing to worry about expanding the system. The outback Inverter was chosen to allow maximum flexibility since a second 3600w can be added easily and will allow for automatic switching to 240v, something that will come in extremely handy if we do expand and need to lengthen our wire runs for further outlying sites. We had used an Ourback Flexmax 60 on our house system previously so were comfortable with that and we also liked the idea of having a fully integrated system.

The largest system component, the panels, were driven down from the U.S. in the bosom of a vintage coleman pop-up camper . The 12 200w panels used for the system was the exact number and  size possible to fit the space the camper provided while maxing out the carry and towing capacity of both the pop-up itself, as well as the Honda CRV used to pull the load. The only reasonable alternative to bringing in our own batteries would have been purchasing them from Vallarta’s only solar store (since gone out of business) with a very limited selection and exorbitant pricing. 175watt panels there were going for 1600 pesos each (about $1,400 - no wonder they’re out of business!) compared to the $425 per 200watt panel we paid to our supplier back in the United States.

As for batteries, we chose the Trojan t-16‘s because they allowed us to get at least a full day of reserves at peak usage with only two stings (48v = (8) 6v batt’s per string) thus allowing for less maintenance and less chance of unequal charging issues than a system with smaller amp/hour capacity batteries such as t-105’s would provide. Being Mexico, the fact that t16’s also weigh to much for someone to walk off with was an additional bonus. Fortunately we have developed a great relationship over the years with a local battery supplier of the Vallarta golf courses, so the pricing on these was roughly the same that we would have paid in the United States.

Other design considerations included orienting the building directly south for maximum efficiency plus a 20 degree pitch to the roof construction. The roof angle decision was pure questimation and a bit of a toss up since a steeper pitch would have given better results in winter when the campground is more likely to see peak usage, versus a shallower pitch which would better accommodate the summer sun angles and yield maximum production during the rainy season. In the end the 20 degrees was chosen as that it the latitude of Mayto and therefore strikes an exact compromise between the two seasons.

The combination “solar shed” and bathhouse was situated at the middle of a rough circle of campsites to keep the 110v wire runs as low as possible (less than 100 ft each for both voltage drop, and cost of wire run considerations), while also minimizing building costs by combining it with the other facilities. The solar components are situated in a “bodega” utility room, completely separate from the other guest facilities.

A further consideration for the building design was that of potential wind loading since we are located in a hurricane zone. Normally hurricanes pass on by the coast here on their way to Cabo San Lucas and the Baja Peninsula, however the area here has seen occasional strikes over the years so we wanted to be sure we’d be ready for one. The result of all this is that our adobe building which normally wouldn’t require much in the way of structural framing, was designed around a extra beefy post and beam style framework of 10” locally grown, log style, hardwood framing. We forwent off-the shelf mounting rail packages in favor of aluminum rails fabricated locally and through bolted to oversized strapping and roof joists securely tied in to the structural framing.

Yet another environmental consideration for our system were the plentiful and intense thunder storms the area experiences during the rainy season. Planning for this we pulled out all the stops with our lightening protection by adding both AC and DC lighting arrestors at virtually all points possible, in addition to following normal grounding procedures.

System Diagrams:

System Grounding & Lightening Protect.pdf

System Overview (coming soon)

Construction of the new off-grid solar bath house!