Solar for small school buses.

[davis mounger]

Greetings. I'm a high school teacher with a bit of solar experience. My classes have built small stand-alone systems as well as a 2K micro-grid tie system. Have some experience in standard system sizing calculations.
My school district is going into the great unknown where parents can choose to send kids to school under an A-B day system to keep numbers down or virtual school at home. It has procured five small buses where roving tutoring can happen for kids with special needs or home challenges. They're taking out the seats and installing tables, laptops, etc. They've asked me to add solar in to power, presumably, some LED lighting, enough power for a few laptops, and, small space heater/cooler. I'm looking for some recommendations on the cooler and heater. The former seating area is about 6 x 12 feet plus the driver seat/step down. I've already told them that a fair amount of the panel/battery needs will be just for the heat and cooling ("resistance heating is costly"). I'm asking them for clarification on probable hours/day, penciling 3-4 days of autonomy, etc. Also looking for recommendations on panel mounting for the roof of the bus.

 

[ianganderton]

@ghostwriter66 and @Will Prowse both have experience with running window mounted aircon units off solar so they would be the people I would want to listen too most

Aircon is really challenging to sustainably run off solar so you need to ensure you’ve stacked the odds in your favour as much as possible first and that means insulate, insulate , insulate!!

 

[davis mounger]

I was looking to see if something like Formular insulation would be feasible, but certainly open to suggestions.

 

[Michael B Caro]

running window mounted aircon units off solar

Window Air Con units on a bus, of any size, are not a great idea. He is talking about mobile classrooms and probably the best solutions for that would be a RV rooftop air or a mini-split. Both have been very successfully used for mobile applications and would both look and perform better than window air. Both can also be purchased that provide heat as well as cooling. In a small bus, it would only take one unit to cool or heat it. Depending on just what configuration the bus has, the most efficient and best choice would be a mini-split. I have two mini-splits on my 40' bus. Running one on solar is a piece of cake.

 

[davis mounger]

Thanks. Is there a particular brand/model of mini split you would recommend that would scale well to this size of a bus?

 

[DASH]

If You are on a budget, You might wish to skip the solar, and build a Lithium Phosphate Battery. You probably could build a 6,000 watt battery for under $2500, and then charge the batteries every night. Later You could add solar.

 

[Michael B Caro]

Brand matters very little. If these are small busses, a 12K btu, inverter, heat pump, 110v unit.

I just installed one like this three weeks ago on a bus.

Daizuki 12000 BTU Air Conditioner Mini Split 19.0 SEER2 INVERTER Heat Pump 110V | eBay

Awesome unit! MINI SPLIT 12000 BTU COOL/HEAT, FREE INSTALLATION KIT, INVERTER + WIFI INCLUDED 110V.

www.ebay.com

 

[davis mounger]

Brand matters very little. If these are small busses, a 12K btu, inverter, heat pump, 110v unit.

I just installed one like this three weeks ago on a bus.

Daizuki 12000 BTU Air Conditioner Mini Split 19.0 SEER2 INVERTER Heat Pump 110V | eBay

Awesome unit! MINI SPLIT 12000 BTU COOL/HEAT, FREE INSTALLATION KIT, INVERTER + WIFI INCLUDED 110V.

www.ebay.com

Interesting. What's the power consumption on this?

 

[Michael B Caro]

about 600w-800w when running and very little more on start up because of the inverter technology.