The limits of my 1185 watt solar system

[jimindenver]

With the recent 100 degree heat I was running the little A/C from as early as 8:30 in the morning until 5 in the evening off of the solar system and batteries. After 5 the solar was not able to run it so I either switched to the generator or simply shut down allowing the solar to get something back into the bank for that night.

What's running is the A/C that while rated for 410 watts is showing as high as 598 watts on a killawatt. The Engel freezer, a 20 inch box fan, two lap tops, any number of hotspots, phones, various chargers plus the regular loads of the trailer. There were no bones left over for the batteries.

From the 25th of April until the first of May the total system produced 2851 Ah or 34,212 Wh. The trailer's 750 watts of flat mounted solar produced 1578 Ah/ 18,936 Wh and the trucks tracking 435w did 1273 Ah/ 15,276 Wh. At times the truck was unattached or not always pointed perfectly, so it could have been higher.

Peak output for a day was 646 Ah/ 7,752 Wh which could have been better again with better management of the truck early and late.

Peak production was just over 34 amps from the truck panel and just over 54 amps off of the roof for over 88 amps combined. Not bad for poly panels that some claim are susceptible to the heat. 

Now as for why the little A/C started pulling more than it should, I can only guess. It could be damage over time from using a industrial MSW inverter. It could be from running too hot built in as I have. It may have lost a run capacitor as the change was sudden and while it was running on the PSW output of the generator.

The generator itself is showing the effects of the stress too. A few weeks ago I started noticing that it was running lean and hot. Now it needs partial choke to stay running. I will find someone that wants to play with it and buy a dual fuel 2000 watt unit. 800 watts is not enough to run the A/C like it is nor my 55 amp converter when I need it.

I did see that the 800 watt version is on sale at Home Depot for $189. There is a new version that will be parallel-able but they want $449 for it.

 

[highdesertranger]

hey buddy what's up? say hey to Max. those are some impressive numbers. highdesertranger

 

[Almost There]

I did see that the 800 watt version is on sale at Home Depot for $189. There is a new version that will be parallel-able but they want $449 for it.

I'm a big fan now of using dual generators and a parallel cable. I had to go to two units to power my battery charger and still be able to lift it

Reasons:

- gas use for one thing. After my battery charger comes off of bulk I can shut down one generator and let only the one unit finish up the charging cycle. 

- Weight. As we age we're less likely to be able to heave those heavier bigger units around. And it doesn't matter how big and strong one is now, we should all be thinking about saving our backs from strain.

- Loan ability! I can't begin to count the number of times I've loaned out a single generator for someone else to use in an emergency or when they need to run power tools. Mine are so completely  portable that it makes it easy to do so.

Just some things to consider in buying either a larger unit or a second one that can be used in parallel.

 

[ZoNiE]

Hi Jim,
What do you have for a battery banK?
How many BTU is your AC unit?

 

[brahmon]

hi jim! i modeled my rig after yours with a 1200w/700ah system. currently running a portable 10000btu ac i got off craigslist for $30. works great!

only problem is the thing is a watt-hog and sucks 1330 continuous watts so run time is limited. gonna have to buy a more efficient ac.

thanks for your great videos man!

 

[4RunnerBlues]

Almost there, what kind of generators do you have, and how much do they weigh?


Sent from my iPhone using Tapatalk

 

[bullfrog]

Could you not isolate part of the battery bank with a three way switch and use the new cheap charger or temporarily borrow one to bulk charge a few hours each day until you find the reason for your increased usage? I'm sure with all of us you have helped someone will be happy to help who is close by your location.

 

[ckelly78z]

"a 20 inch box fan, two lap tops, any number of hotspots, phones, various chargers plus the regular loads of the trailer. There were no bones left over for the batteries."

I think the A/C might be fine without all the other loads you have running at the same time. I understand the freezer is needed, but the chargers could be used at night, and two laptops, multiple hotspots, and a large box fan ? There might be more efficient ways of doing the same things with better timing.

 

[lenny flank]

Hah! I don't even know what I would DO with that many watts. I might never leave the van.

I get along just fine with my 100w panel and 100ah battery.

 

[Almost There]

Almost there, what kind of generators do you have, and how much do they weigh?

I have a pair of Honda 1000Ei's and a parallel cable that joins them together to give me the power of a 2000Ei.

The 1000s' each weigh in at about 27 lbs. A 2000 weighs in at 47 lbs.

I could lift the 2000 off the ground but being short I couldn't lift it high enough to put it in the back doors of the van - I would have had to been able to lift it all the way to high chest height. If I were 30 years younger and a foot taller, it would have been a different story...

I have to admit that I already owned one of the generators so I simply added a second one and the parallel cable.

 

[4RunnerBlues]

Cool. Thanks. I have an 800/1000 generator that weighs 19 lbs. but doesn’t have the parallel ability. Anyone know how to hack it? I have the same generator as jimindenver, the Sportsman bought on sale for $150. I would buy another if I could make it work.


Sent from my iPhone using Tapatalk

 

[jimindenver]

Hi Jim,
What do you have for a battery banK?
How many BTU is your AC unit?

I have three very old Lifeline 8 D's that at one time were good for 675 Ah.

The A/C is 5000 BTU'S

 

[jimindenver]

Could you not isolate part of the battery bank with a three way switch and use the new cheap charger or temporarily borrow one to bulk charge a few hours each day until you find the reason for your increased usage?  I'm sure with all of us you have helped someone will be happy to help who is close by your location.

i have very kind offers of 2000 watt generators. I do have a smaller charger but even it is over heating the generator.

 

[Weldman]

It's nice and cute everything to have the solar panel wattage to run a A/C though. So unless one lives in temps requiring it year around I find it overkill to drag it around when one uses it about 6 months years at most plus all the batteries to maintain and drag around.
Easier to drag around a 2k inverter genny to pick up the slack. To each their own I know...

 

[jimindenver]

I do a lot more than just run the A/C with my solar system. When both the A/C and generator are running correctly I can run the A/C no problem. I can't stand the noise or the gas runs but as you said, to each their own.

 

[Knit]

What's running is the A/C that while rated for 410 watts is showing as high as 598 watts on a killawatt.
Now as for why the little A/C started pulling more than it should, I can only guess. It could be damage over time from using a industrial MSW inverter

Could it be that the Kill-a-Watt meter itself is inaccurate with a MSW inverter?

 

[Zoomyn]

As ambient temperature go up so does the power requirements of the A/C compressor, refrigerant pressures climb along with temperature. Also the resistance of the copper motor windings, conductors etc. go up too, not much on the hour to hour usage but over the season its a factor.

Keeping the condenser coils & A/C frame out of direct sunlight can/will boost efficiency 5-10%.

Increasing outside condenser air flow by reducing intake restriction would be a solid boost - maybe a hottest-weather-only intake that is kept plugged during cooler season?

If your interior air is already 'desert dry' this won't be much help but most small units cheat by including a condensate splash tab on the condenser fan blade, the droplets do a liquid-to-gas water evaporation on the coils of the condenser to nudge efficiency up a goodly amount.

If we tilt the A/C unit to make sure the condensate drains fast to reduce chances of flooding we're losing some real performance. Since humidity is often nearly infinite in hot coastal regions it'd be adding gallons (say 5kbtu makes 1 pint per hour x 24hr = 3 gallons/day) to catch the last 5 or 7% efficiency - so tending to an even leveling of the A/C unit (near impossible on most trailers) would make solar wattage go further....

 

[RogerD]

Here's an article that shows how power consumption increases when airflow is restricted.

https://www.buildagreenrv.com/window-air-conditioner-to-cool-an-rv/

 

[wayne49]

Could it be that the Kill-a-Watt meter itself is inaccurate with a MSW inverter?

My experience with a Kill-a-Watt on a switched PSW, or MSW, inverter, is that the clock on the K-a-W will be inaccurate for displaying the actual time that the inverter was supplying power.

How that might affect the energy usage values, IDK.

I am not at my base camp and do not have access to the relevant spreadsheets to give the specific differences in the time values.

 

[Headache]

Pita, Lily and I are incredibly grateful to his dying components for keeping us cool in those temps. And not so grateful that now I must put a/c in my van. lol

You're killin' me Jim!