William - As others have pointed out, there are all sorts of factors that would increase or decrease energy consumption for an AC unit. I like to refer to the Energy Star guide to get an idea of average annual energy consumption:
https://www.energystar.gov/products/most_efficient/central_air_conditioners_and_air_source_heat_pumps At least these numbers can be used as a reference point, and you could for example divide the total annual energy use by the number of months you'll be running the system to get a rough kWh/month starting estimate. Then adjust as necessary based on your site specific situation such as a really hot climate, home size, poor insulation, etc. August PS: I think you assume 12,000 Btu/hr for each ton of AC capacity, so a 5 ton AC unit would be 5 x 12,000 = 60,000 Btu/hr On Wed, Jun 23, 2021 at 12:19 PM la...@starlightsolar.com < la...@starlightsolar.com> wrote: > William, > > The LRA of an A/C system is the peak current demand. The inverter must be > sized for that and all other potential loads if using a single inverter. > For that reason, we have almost always used a dedicated inverter for an A/C > systems and leave the primary inverter for all other loads. That way the > A/C will start no matter what other loads are on the primary inverter. > > Install a hard start capacitor unit (sometimes now called soft start) if > it is not factory equipped with one. Using Li-ion batteries is also > recommended due to voltage sag using LA. Otherwise, you may want to size a > LA bank larger for the additional current demand while starting. > > We have been doing separate inverters for 120V RV A/C’s and 240V mini > splits this way for years and it has been trouble free. > > Larry Crutcher > Starlight Solar Power Systems > > > > > > On Jun 23, 2021, at 9:30 AM, William Miller <will...@millersolar.com> > wrote: > > Friends: > > > In the old days when a client suggested they might want to run air > conditioning equipment on an off-grid system we would just laugh. Now I > find I get that request more frequently and clients are willing to pay to > acquire enough system capacity to run AC equipment. > > > This means I need to size off-grid installations appropriately for the > loads. I have a job pending with a 5 ton AC unit. I cannot find real-life > energy specs. > > > I do have a new, fairly efficient 3 ton unit at my grid-connected home and > I do have energy monitoring. On a real hot day recently we used a little > less than 11kWh in this unit. The max power draw was about 2.5 kW. > > > Here are my questions: > > > 1. Can I linearly extrapolate my usage to a 5 ton unit? > 2. Do any of you have real-life, measured energy data on modern AC > condenser units that you would be willing to share? > > > Thanks in advance! > > > William Miller > > > Miller Solar > 17395 Oak Road, Atascadero, CA 93422 > 805-438-5600 > www.millersolar.com > CA Lic. 773985 > > > > > _______________________________________________ > List sponsored by Redwood Alliance > > Pay optional member dues here: http://re-wrenches.org > > List Address: RE-wrenches@lists.re-wrenches.org > > Change listserver email address & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > There are two list archives for searching. When one doesn't work, try the > other: > https://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/ > http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org > > List rules & etiquette: > http://www.re-wrenches.org/etiquette.htm > > Check out or update participant bios: > http://www.members.re-wrenches.org > > _______________________________________________ > List sponsored by Redwood Alliance > > Pay optional member dues here: http://re-wrenches.org > > List Address: RE-wrenches@lists.re-wrenches.org > > Change listserver email address & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > There are two list archives for searching. When one doesn't work, try the > other: > https://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/ > http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org > > List rules & etiquette: > http://www.re-wrenches.org/etiquette.htm > > Check out or update participant bios: > http://www.members.re-wrenches.org > >
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