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
Here's a few more details on my proposed FT boondocking solar ac system.
The Heat Pump I linked to in the previous post produces 12,000 BTUs of cooling from only 560 watts of power. There are no inverter losses converting the DC voltage to AC. The downside is that this unit costs around $2,000. It's not cheap, but it will surely pay for itself in energy savings over time.
Here's a link where they suggest a solar bank of only 1,120 watts would be required, (based on 12hrs of power consumption and 6 avg. hours of sunlight.) This kind of rotary compressor doesn't cycle like a "normal" ac piston compressor but scales up and down as required, so it has no start-up surge typical of conventional acs. http://www.geinnovations.net/solar-electricity-cost.html
12,000 BTUs of cooling from 560 watts is an EER of 21.43. This means that you can get 1 ton of cooling power for about the same energy as that tiny 5,000 BTU window shaker uses (less power draw when the start-up surges and inverter inefficiency is taken into account.
The 435 watt solar panels I linked to cost only 69 cents/watt, so only 4 (aprox. 4x8ft panels) will make 1740 watts of power for about $1,200.
8 Energizer CG-2 (golf cart) deep cycle FLA batteries from Sams Club cost about $84 ea. producing 104 usable AH (at 50% draw) wired in series at 48v. Since this ac only draws 11.5 amps (at 48v DC) that $672 battery bank will give me 9 hours of ac run time at full power. Practically, the ac will never run at full power all night, but will scale back cooling and power draw, easily providing a full night of use. When the sun is shining, 1740 watts of solar (run through a TriStar-45 MPPT controller) will easily make 25+ amps giving me 11.5 amps to run my ac during the day and another 13.5 amps to recharge my batteries from the previous night.
Now life is not perfect, so occasional generator use may be required to top off my batteries, but this is as close to totally solar powered AC as you can get for a minimal cost. On a side note, a single EU2000 Honda will easily run this high-efficiency AC and charge my batteries at the same time if needed. $700 batteries and cables, $1,200 solar panels, $500 controller, $400 cables, (high voltage takes smaller wires), brackets and misc. hardware = less than $3,000 system cost. 12,000 BTUs may not cool my entire 30ft RV, but will surely cool my bedroom for sleeping and probably a little extra too, improving the comfort level immensely, even if it can't maintain a perfect 70 degrees inside in peak daytime heat. That's when I plan on being outside most of the time anyway.
I plan on also having a 12v system too (2 GC-2's, 30a Tracer MPPT controller and a 300 watt panel, for slides, fridge board, heater blower, lights, etc.) - about $600, along with a 48v AIMS inverter/charger ($665) boosting my total system price to around $4,500 give or take a couple bills. The main problem is weight, about 1,100 lbs for the total system (as I can't afford LiFePO4 batteries at today's prices).
Chip
The Heat Pump I linked to in the previous post produces 12,000 BTUs of cooling from only 560 watts of power. There are no inverter losses converting the DC voltage to AC. The downside is that this unit costs around $2,000. It's not cheap, but it will surely pay for itself in energy savings over time.
Here's a link where they suggest a solar bank of only 1,120 watts would be required, (based on 12hrs of power consumption and 6 avg. hours of sunlight.) This kind of rotary compressor doesn't cycle like a "normal" ac piston compressor but scales up and down as required, so it has no start-up surge typical of conventional acs. http://www.geinnovations.net/solar-electricity-cost.html
12,000 BTUs of cooling from 560 watts is an EER of 21.43. This means that you can get 1 ton of cooling power for about the same energy as that tiny 5,000 BTU window shaker uses (less power draw when the start-up surges and inverter inefficiency is taken into account.
The 435 watt solar panels I linked to cost only 69 cents/watt, so only 4 (aprox. 4x8ft panels) will make 1740 watts of power for about $1,200.
8 Energizer CG-2 (golf cart) deep cycle FLA batteries from Sams Club cost about $84 ea. producing 104 usable AH (at 50% draw) wired in series at 48v. Since this ac only draws 11.5 amps (at 48v DC) that $672 battery bank will give me 9 hours of ac run time at full power. Practically, the ac will never run at full power all night, but will scale back cooling and power draw, easily providing a full night of use. When the sun is shining, 1740 watts of solar (run through a TriStar-45 MPPT controller) will easily make 25+ amps giving me 11.5 amps to run my ac during the day and another 13.5 amps to recharge my batteries from the previous night.
Now life is not perfect, so occasional generator use may be required to top off my batteries, but this is as close to totally solar powered AC as you can get for a minimal cost. On a side note, a single EU2000 Honda will easily run this high-efficiency AC and charge my batteries at the same time if needed. $700 batteries and cables, $1,200 solar panels, $500 controller, $400 cables, (high voltage takes smaller wires), brackets and misc. hardware = less than $3,000 system cost. 12,000 BTUs may not cool my entire 30ft RV, but will surely cool my bedroom for sleeping and probably a little extra too, improving the comfort level immensely, even if it can't maintain a perfect 70 degrees inside in peak daytime heat. That's when I plan on being outside most of the time anyway.
I plan on also having a 12v system too (2 GC-2's, 30a Tracer MPPT controller and a 300 watt panel, for slides, fridge board, heater blower, lights, etc.) - about $600, along with a 48v AIMS inverter/charger ($665) boosting my total system price to around $4,500 give or take a couple bills. The main problem is weight, about 1,100 lbs for the total system (as I can't afford LiFePO4 batteries at today's prices).
Chip
