TalkBaja.com » Baja Mexico Forums » Off-Grid / Solar, Wind or Generator?

About a year ago I posted a question about the feasibility of running mini-split AC units on a solar powered house in Baja.

Off-Grid Info

Well with temps in Loreto in the low – mid 90’s lately, we have been running our mini-splits at night to cool off the bedrooms so we can sleep more comfortably. The units we have are the Mirage FUXION 1 ton units. (I cheaped out and didn’t spend the extra money for inverter controlled units that would have been even more energy efficient) These units draw 1000 watts total when running. My theory that the compressor unit would only run about 1/3 of the time didn’t work out as the room never reaches an equilibrium temperature as set on the thermostat. I’m sure this is because the temperature of the walls, floors, ceiling and everything in the house is sitting at about 89 F, and it is impossible for the unit to cool down all this massive heat sink in a few hours.

If we run one unit all night, it brings my battery bank down to about 65% SOC (Temp corrected S.G.~ 1.20). My solar panels can then charge back up to “Float” stage by late in the day. Without running AC, I would be at 85% SOC and in Float by about 1:00pm each day. What we have found to be most effective is to set the AC timer to run about 3 – 4 hours right as we go to bed (around 10:00pm), then just use the ceiling fan for the rest of the night. This allows us to get to sleep comfortably and the room stays OK with just the fan on the rest of the night.

This past week has been interesting as we have had our daughter visiting and we are now running two units. Spot checks of S.G.’s in the morning show about 1.17 or about 50% SOC. Not ideal, but I can live with that for a while, especially considering that my SOC is usually about 85% when not using AC, which is most of the year. On top of that we have had cloud cover for at least half of the day. With this situation, I can’t reach Float with solar panels alone and have been running the generator for an hour or so at the end of the day. I think when the clouds go away, it will not require the generator run at all.

Overall, I’m happy with the results, although running this limited AC will stress my system a bit. Looks like my plans for an RO watermaker will have to be put on hold till I consider the idea of increasing my battery bank and solar array a little more.

Is your roof insulated? Walls?Just wondering if there is anything you could do there to help keep the heat out during the day which will go a looooong way to help reduce the cooling needs at night?

Is your battery bank still 1300ah of batteries running at 48 volts?

Any possibility of adding more batteries?

Originally Posted by BajaGringo

Is your roof insulated? Walls?Just wondering if there is anything you could do there to help keep the heat out during the day which will go a looooong way to help reduce the cooling needs at night?

Is your battery bank still 1300ah of batteries running at 48 volts?

Any possibility of adding more batteries?

We have the typical foam/concrete roof and we do have two inches of foam on the outside of all the block walls. All windows/doors are double pane, low E glass. As this is our first summer in the house, we're still trying to figure out the best "heat management" stratgy, eg. open windows at night, close up house in AM etc. Our friends with a totally non-insulated house have it pretty well figured out and they can keep their house pretty cool during the day. We still are putting up window coverings and working on "sun management".

I have the same solar setup as I first described. As my batteries are coming up on one year old now, it's kinda decision time if I want to put another string in the system. I'm thinking YES, but my bank account is just about empty so am thinking it over. I was serious about the RO system, but that is another energy hog. I would probably need another 1000 watts of panels also. Would sure like to get rid of that water truck. We'll see how it goes.

Originally Posted by ncampion

We have the typical foam/concrete roof and we do have two inches of foam on the outside of all the block walls. All windows/doors are double pane, low E glass. As this is our first summer in the house, we're still trying to figure out the best "heat management" stratgy, eg. open windows at night, close up house in AM etc. Our friends with a totally non-insulated house have it pretty well figured out and they can keep their house pretty cool during the day. We still are putting up window coverings and working on "sun management".

I have the same solar setup as I first described. As my batteries are coming up on one year old now, it's kinda decision time if I want to put another string in the system. I'm thinking YES, but my bank account is just about empty so am thinking it over. I was serious about the RO system, but that is another energy hog. I would probably need another 1000 watts of panels also. Would sure like to get rid of that water truck. We'll see how it goes.

Keeping the house dark / closed in the hottest hours will help significantly - that would be a good move. As far as going with an RO system and getting rid of the water truck, I am teetering between that and just buying a water truck...