Running A/C on solar.
I want to do a solar setup on my new TT. One big enough to run the A/C. I'm thinking of getting an inverter big enough to run the A/C, and just running the shore power cable to it when I'm camping...
Forum Discussion
A typical 13.5 BTU RV air conditioner will draw 12-15 amps of current when operating (a bit more when starting for the instantaneous lock rotor draw). For the sake of this example lets say the AC draws 14 A on average. 14A at 120V = 140 A at 12V (probably a bit more considering inverter and wiring losses). A 12V typical RV Marine hybrid battery has a capacity of around 100AH at the 20 hr. rate. That is 5A/hr for 20 hr and the battery is completely discharged and wouldn't light a flashlight bulb, much less run an air conditioner. Since we would wish to use the battery on the second and following days, we would discharge it only 50%. That makes available 2.5 A for 20 hrs. Now we can buy some batteries...56 of them to operate the air conditioner for 20 hrs a day.
But wait, you're going to have solar power available and that will recharge the batteries while the AC is on. How much will you need? To break even for the 20 hr run of the AC, you'll need to replace 2800 Amp Hours or 33,600 Watts. If you use 230-250W solar modules, you'd need 26 of them at typical insolation and typical controller/wiring losses. You would also need a big solar controller and some serious wiring to handle the 6700 W being harvested from the modules.
I hope this example shows the impractibility of solar and typical AC use. There are a few members experimenting with low draw AC units and solar. They are using 5K window units and a minimum of 3 250W modules. The requisite battery bank is needed along with temperate weather to accomplish the task.
But wait, you're going to have solar power available and that will recharge the batteries while the AC is on. How much will you need? To break even for the 20 hr run of the AC, you'll need to replace 2800 Amp Hours or 33,600 Watts. If you use 230-250W solar modules, you'd need 26 of them at typical insolation and typical controller/wiring losses. You would also need a big solar controller and some serious wiring to handle the 6700 W being harvested from the modules.
I hope this example shows the impractibility of solar and typical AC use. There are a few members experimenting with low draw AC units and solar. They are using 5K window units and a minimum of 3 250W modules. The requisite battery bank is needed along with temperate weather to accomplish the task.
