Newb - What size do I need to run a......

[adoublee]

SDaniels - you can do this without a generator and should. In an emergency grab some dry ice from the store as you suggested. It's only 50 summer days your working to address here. You just need to make sure you don't kill the batteries necessary to get the system going.

Can I assume you are already looking at Coolbot to turn the A/C into a cooler?

Make sure first and foremost you are super well sealed and super well insulated. Also make sure any staff knows that trips in and out of the cooler are to be limited.

Use mini-splits. Look for Panasonic 20 SEER ultra high efficiency. Regularly used in battery powered trailer conversions.

Learn about lithium battery and use it correctly/safely. This will be an investment (nowhere near $30k for all of this) of time to learn and dollars to figure out, but these batteries don't need to be topped off every day, can sit unused over the winter, etc. Plus no sulfuric acid around or hydrogen to vent.

As suggested, don't mess with 100W 12V or 24V panels. You want the standard higher voltage (and higher power density) panels paired with an MPPT charge controller capable of a relatively high input voltage. Then you need an inverter connected to the batteries capable of supplying the very low amperage of this split system with low start-up current. Do not skip fusing - batteries can dump a great deal of energy quickly.

If you don't have $5-8k to do this move on to another idea. If that is reasonable, consider making it worth someone's time to help you out.

Good luck and hope you are able to impress your wife!

[Sunking]

sorry but the problem is that i make my calculations based on the "sunny land" libya

i correct you sir ....we do have strong sun 8 hours in winter and we do have 12 hour of sun in the summer continous with no rains and no stroms

Not sun hours.

[Sunking]

I run with a minimal battery system that is used primarily for motor starting.

Completely unsuitable and foolish.

[jflorey2]

So let's say I run the unit only in daytime hours on a timer, as the box should stay cold enough overnight.
Would I need a battery bank?

Yes, but it would be a bit smaller. (Not much smaller, since I assume you want to run on cloudy days as well.)

What is the smallest panel array I could get a way with to run an AC unit?

Get a kill-a-watt or similar meter. Run the A/C for one day. Determine kwhrs needed. Then figure out the equivalent peak sun-hours for your location. A little math and you'll have your answer.

Unit rated to draw 5 Amps at 110 VAC while compressor is running and <1 Amp when idle (fan only).

So it will take between 2.3 and 14.4kwhr a day. That's a wide range. Use the meter to narrow it down.

Would I need one battery to make the inversion to AC?

No, you need the battery to supply the energy (and power) needed by the A/C. The solar system then "refills" the battery.

[Sunking]

I'd be disappointed if you said anything different. The last PE I dealt with had crap running uphill. Things haven't changed.

1200 watts on a 12 volt SLI battery is Crap Running up hill and disqualifies you as an expert. If you knew anything about batteries you would understand. Let's hear all about your 100 amp 12 volt charge controller?

Keep it up and you might find yourself on the outside looking in giving bad dangerous advice pretending to be an expert. That will get you banned real quick. You have no credibility here. You lost it a long time ago.

[J.P.M.]

Not sun hours.

A good example of the (unnecessary, IMO) confusion caused by using an anachronistic term. Sun hours may be good for a non quantitative dart throw at relative sunniness of an area. Poor for quantitative purposes.

Gendil: Sun hours is another name for daily global horizontal insolation at a location, often and commonly abbreviated as daily GHI, or average daily GHI if over some calendar period - a week/month/year/etc. The conversion: 1 sun hour == 1kWh/m^2 on a horizontal surface.

FWIW, In Libya, looks like you get ~ 3.5 kWh/m^2/day GHI in Jan. and ~ 8.1 kWh/m^2 GHI in July from rough maps of data, but check other sources. Daily average over a year looks to be ~ 6 to 6.5 kWh/m^2 daily GHI.

[Sunking]

FWIW, In Libya, looks like you get ~ 3.5 kWh/m^2/day GHI in Jan. and ~ 8.1 kWh/m^2 GHI in July from rough maps of data, but check other sources. Daily average over a year looks to be ~ 6 to 6.5 kWh/m^2 daily GHI.

That means a low of 3.5 Sun Hours in Jan, and a max of 8.1 Sun Hours in July. Pretty much what the desert SW USA gets.

JPM I use Sun Hours because this is a DIY site. You and I know what kWh/m^2 means because we are engineers. Most DIY's do not have a clue what that means unless they have an engineering or technical background and understand fairly simple math.

No place on earth gets 12 Sun Hours or 12 kWh/m^2 to my knowledge. Well perhaps Mt Everest on a crystal clear day in Late March if there is any such thing as a clear day there. Good luck getting up there with panels and batteries.

[J.P.M.]

That means a low of 3.5 Sun Hours in Jan, and a max of 8.1 Sun Hours in July. Pretty much what the desert SW USA gets.

JPM I use Sun Hours because this is a DIY site. You and I know what kWh/m^2 means because we are engineers. Most DIY's do not have a clue what that means unless they have an engineering or technical background and understand fairly simple math.

No place on earth gets 12 Sun Hours or 12 kWh/m^2 to my knowledge. Well perhaps Mt Everest on a crystal clear day in Late March if there is any such thing as a clear day there. Good luck getting up there with panels and batteries.

I appreciate and respect your perspective, but without trying to be argumentative or disrespectful, for you to say this is a DIY site seems to me a bit like the pot calling the kettle black, given your prodigious contributions - seriously. Few, including me, have the same generous nature. For those who wish to learn, it's a real source of knowledge, and the devil take the hindmost. Same with correct, more descriptive and dimensionally correct terms for insolation.

Yes, we are engineers. And part of what goes with the profession, as you often exemplify, entails a bit of education if only to help avoid confusion, as perhaps exhibited with this sun hours thing. I'm far from a crusader, but, IMO, the gain from using a more descriptive and what is, IMO, a bit more useful and technically correct term for calculation and descriptive purposes, and dropping one that is anachronistic and a dead end as well as ambiguous may be worth the small price.

We don't calculate velocities in furlongs per fortnight any more either.

[gendil]

A good example of the (unnecessary, IMO) confusion caused by using an anachronistic term. Sun hours may be good for a non quantitative dart throw at relative sunniness of an area. Poor for quantitative purposes.

Gendil: Sun hours is another name for daily global horizontal insolation at a location, often and commonly abbreviated as daily GHI, or average daily GHI if over some calendar period - a week/month/year/etc. The conversion: 1 sun hour == 1kWh/m^2 on a horizontal surface.

FWIW, In Libya, looks like you get ~ 3.5 kWh/m^2/day GHI in Jan. and ~ 8.1 kWh/m^2 GHI in July from rough maps of data, but check other sources. Daily average over a year looks to be ~ 6 to 6.5 kWh/m^2 daily GHI.

i didnt mean sunhour i dont understand these terms i only mean we have got alot of sun ...7 hours of full bright sun at winter more than 8 full bright at summer ? that is what i mean

[SunEagle]

i didnt mean sunhour i dont understand these terms i only mean we have got alot of sun ...7 hours of full bright sun at winter more than 8 full bright at summer ? that is what i mean

I guess the discussion involves the misconception most people have is that"if the sun is up my panels are producing full power".

The reality is that even if the sun is above the horizon and bright it may not be at the correct angle over the panels for them to produce power anywhere close to their nameplate wattage. The number of hours for "full" production will always be less then when the sun is above the horizon.

[J.P.M.]

I guess the discussion involves the misconception most people have is that"if the sun is up my panels are producing full power".

The reality is that even if the sun is above the horizon and bright it may not be at the correct angle over the panels for them to produce power anywhere close to their nameplate wattage. The number of hours for "full" production will always be less then when the sun is above the horizon.

If nothing else, using the technically correct term (kWh/m^2 per day, or often abbreviated as average GHI/day = Global Horizontal Insolation per day) may help avoid sending folks down the wrong road of assumption, or at least flag them that things may not be as they seem. The nomenclature's unwieldiness but none the less necessity when trying to estimate output from solar devices has been a PITA for all since the '50's or before, but the term "sun hours" does little more than increase confusion for the non technical crowd looking for estimates of system's performance.

Then, there's the next issue that your 2d paragraph alludes to, that of understanding that GHI needs to be converted to what an array will actually "see" over the course of a day (something called Plane Of Array Insolation or the perhaps faster to say "POA insolation per day) and how that necessary quantity is affected by an array's orientation.

[SunEagle]

If nothing else, using the technically correct term (kWh/m^2 per day, or often abbreviated as average GHI/day = Global Horizontal Insolation per day) may help avoid sending folks down the wrong road of assumption, or at least flag them that things may not be as they seem. The nomenclature's unwieldiness but none the less necessity when trying to estimate output from solar devices has been a PITA for all since the '50's or before, but the term "sun hours" does little more than increase confusion for the non technical crowd looking for estimates of system's performance.

Then, there's the next issue that your 2d paragraph alludes to, that of understanding that GHI needs to be converted to what an array will actually "see" over the course of a day (something called Plane Of Array Insolation or the perhaps faster to say "POA insolation per day) and how that necessary quantity is affected by an array's orientation.

Too bad they couldn't make a cheap tracking system that mimic's sunflowers. That would certainly increase the output.

[J.P.M.]

Too bad they couldn't make a cheap tracking system that mimic's sunflowers. That would certainly increase the output.

Funny you should mention that - and not funny at the same time really.

Back in the day and back in Buffalo, I had a small spot in my yard that was mostly sheltered from the weather but had no shade. One year, late Feb./early March I noticed a small flower called a snowdrop, a flower that blooms very early under the right conditions had popped up as a volunteer in that spot. It has a stem and a flower that droops, with the flower pointing sort of south, but not entirely - this one pointing at ~ 160 or so degrees azimuth. So, being curious, and knowing that winters in Buffalo are usually sunnier (when the sun does shine in the winter in Buffalo) before noon, I made sure of a few more snowdrops in the same area as the original were present the next few years and made anecdotal observations/measurement the next year or two. Long story short, the snowdrops seems to have an azimuth that maximizes, or at least seems close to an azimuth that maximizes how much solar radiation they receive for their short blooming period of ~ 10 days or so. I also grew sunflowers in front of the sunspace I added to the house as part of a warm weather shading system and generally observed the same results. Kind of a nature driven azimuth optimization system.

Take what you want of the above. Scrap the rest.