kowbra wrote:
So, I talked to the Super Solar designer today and learned a few more details; for those who may be interested in this solution...
-the AC units are not just a soft start added. They draw 9 amps when running, so much more efficient than normal roof top units
-they are now adding 300 watt panels for a total of 1200 watts (noted earlier)
-they will be upgrading the MPPT charge controllers to dual 40 amp models
-there is a panel to remove to add another 500ah of lithium; this could be other manufacturers as long as the charge profile matched
-they are working on a drop in package from Keystone with dual DragonFly GC3 batteries for those who want a turn key 510ah upgrade to a total of 1020ah
-the design goal was that this would serve to run the entire coach and in many conditions would fully charge the batteries each day
-for those who may think their usage may tax or exceed the design, they do have the upgrade path as above, but also are suggesting that a portable generator could be used. For example, in situations where a solar only solution would be taxed, such as cloud, forest, etc, then even a larger system may not be enough. Of course, one could just keep overbuilding with more panels and battery storage to account for worst case scenario... or carry a small 2000w generator to charge the batteries for those times
I do hope this information is helpful for those considering this solution.
We placed our order including the Super Solar Flex and will be trying it out later this year. I will update all once we are able to test it.
Brad
Coleman Mach only makes one large unit that pulls 9A, the Mach 3 PS. It's a 13,500 BTU/ 12.5 EER unit that draws 9 to 11A when cooling.
Datasheet here. Assuming you require two of them to cool your rig, that doesn't change the math all that much. In the heat of the day, with near perfect solar, you would at best break even on the AC alone (over the course of an hour) with 1200W of panels if running only one unit full out, or two on a 50% compressor cycle. It doesn't matter how efficient they are - they're not efficient enough to make the numbers work for running the AC any length of time with that amount of panels.
Assuming you're pulling 9A or 1075W as the datasheet says, and either running two units at 50% compressor or one unit full out to cool your rig, you're pulling 1075W, plus inverter losses. The Magnum MSH3012 series datasheet shows an efficiency of around 87% at 1kW (
datasheet here, see P44) which means you are pulling at least 1215W just for AC alone. This is another reason why 24V and 48V are great options - you have much lower inverter losses at higher voltages, especially as loads increase (as exampled on the same chart on P44, for the 24V MSH4024M).
If you are running nothing but your air conditioning - you can expect to harvest enough energy to run your AC for 4.9 hours. Or if you average a 100W load throughout the day without the AC, 2.9 hours. That's figured with the conventional figure of 5 solar hours * 1200W panels, or 6kW collection per day.
Also worth nothing, most 18-20cu ft residential fridges consume 1.6-2.0kWh per day, depending on conditions. If you account for only a 50W base load, and 1.8kWh for a residential fridge, you collect enough solar to run your AC for under 2.5 hours in ideal conditions, not accounting for the inverter losses of the additional loads.
This system just doesn't seem like a serious attempt by Keystone to offer solar, in my opinion. Also, 1200W of panels will collect around 500AH per day on a 12V system. Doubling your batteries to 1020AH gives you a rainy day, but your panels alone will not be sufficient to fill them back up. What that buys you is the ability to decide when to run your generator, or wait until you get home to plug in if you're only vacationing.
If you go into it with the appropriate expectations, then I'm sure you'll enjoy it.
I just think saying it will "run the entire coach" is a big stretch as most people will buy it expecting to actually be able to run the AC, especially with all the marketing they push about soft starts and high efficiency units. That's going to leave many people sorely disappointed.
You wouldn't be able to run the AC all day, with off the shelf components, for $20K -- but you could get a lot closer than what they're providing you assuming you do the install yourself.
--
We rarely run our generator, by the way - even in cloudy or shaded conditions. 15 hours this year, including an hour each month for maintenance and a few hours for testing when we had some issues with it. With an adequately sized system, you can avoid them for the most part.
