diy solar

diy solar

I am always fantasizing about having a energy efficient air conditioner for van life, anyone seen any concepts in tech news or anything?

guidecca said:
Yes, the Fujitsu unit looks good. Can you recommend any budget models with the high SEER numbers?

I have two 8S2P batteries, total of (16) 3.2V 280Ah LiFePO4 cells, 400W of solar panels, Epever 40A MPPT Tracer, and a Samlex EVO 2224 inverter charger. Would this system run a mini split?

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IMO, the way you will get this system to work is to deploy a 400 watt ground panels that you rotate throughout the day to supplement you roof mounted panels. I think you’d need 20’ of roof mounted panels to get the energy you want for the ac.

I run my 15k btu ac off 2500 watts of panels and the system pulls 1800 - 2000 watts total, of which everything except 100 watts - 200 watts is my standard (NOT mini-split) AC. I have run this 6 hours and I am not draining the batteries to do this.

How much wattage an AC uses is a big mystery, and kindof comes down to you need to power it on to try it. When I hit the on switch, I had one source that told me a 15 k BTU unit pulled 1600 watts, pretty close to what I saw, and another source told me 500 watts, way off. IMO if you turn your AC because you need it, it will run without cycling off in a van or RV. 100% duty cycle. NIne runs 100% of the time and I have managed to get inside temps 20 degrees below outside temps.

A mini split would be more efficient. Since good numbers are hard to come buy, I found a video of a guy, who seems like he knows what he’s talking about, and he said an 8k mini-split would be 500 watts. That is what I would like to have in your van. Maybe it will be too big, but I would rather freeze myself out than be wrong. If it turned out to be 500 watts, remember seems like its a bog secret how much these things actually use, your battery pac is right sized for this to run all night, but an additional 400 watt ground portble panel array would power your ac all day long when the sun is shining, but probably only cover an hour or two of overnight charging.

My estimates tend to over design things. My two or three solar builds either met or exceeded my expectations. That is a big thing for me rather than pumping a lot of money into somethign and not having enough, I’d rather figure out what to do with the extra capacity I have. Now, I’m looking at Level 1 charging from my RV for extra capacity.
 
guidecca said:
Thank you for the ideas; these are long-term projects for me. Here is the battery box for 8s2p and a BMS and there will be two. I had them fabricated in China. In the short term, if I drive 8-10 hours a day with the DC to DC connection how much power would that generate? How would you connect the two 8s2p batteries in the two boxes?
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If you went with 480W as per GSXR suggestion (480W):

8 hours x 480 watts = 3480 Wh (watt hours)
or
8 hours x 20 amps = 160 Ah (amp hours) at 24V nominal
 
chrisski said:
IMO, the way you will get this system to work is to deploy a 400 watt ground panels that you rotate throughout the day to supplement you roof mounted panels. I think you’d need 20’ of roof mounted panels to get the energy you want for the ac.

I run my 15k btu ac off 2500 watts of panels and the system pulls 1800 - 2000 watts total, of which everything except 100 watts - 200 watts is my standard (NOT mini-split) AC. I have run this 6 hours and I am not draining the batteries to do this.

How much wattage an AC uses is a big mystery, and kindof comes down to you need to power it on to try it. When I hit the on switch, I had one source that told me a 15 k BTU unit pulled 1600 watts, pretty close to what I saw, and another source told me 500 watts, way off. IMO if you turn your AC because you need it, it will run without cycling off in a van or RV. 100% duty cycle. NIne runs 100% of the time and I have managed to get inside temps 20 degrees below outside temps.

A mini split would be more efficient. Since good numbers are hard to come buy, I found a video of a guy, who seems like he knows what he’s talking about, and he said an 8k mini-split would be 500 watts. That is what I would like to have in your van. Maybe it will be too big, but I would rather freeze myself out than be wrong. If it turned out to be 500 watts, remember seems like its a bog secret how much these things actually use, your battery pac is right sized for this to run all night, but an additional 400 watt ground portble panel array would power your ac all day long when the sun is shining, but probably only cover an hour or two of overnight charging.

My estimates tend to over design things. My two or three solar builds either met or exceeded my expectations. That is a big thing for me rather than pumping a lot of money into somethign and not having enough, I’d rather figure out what to do with the extra capacity I have. Now, I’m looking at Level 1 charging from my RV for extra capacity.
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Except that he's got a rather small space to cool and he plans to use a mini-split. 12k btu would be more (way more) than enough. My 12k btu mini-split draws ~1200W at full bore. He could probably run it in "silent" mode @ a ~500W draw and it would keep his van cool. He can also find 9k btu mini-splits. He has plenty of viable options for his relatively small space to cool.
 
DerpsyDoodler said:
My 12k btu mini-split draws ~1200W at full bore. He could probably run it in "silent" mode @ a ~500W draw
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Thanks for these benchmarks.

I do estimate he could get a mini-split AC for the van that ran at 500 watts With an 8 k BTU unit if my other benchmark of an 8 k BTU and 500 watts I found is correct, but your 12 k BTU mini-split at 1200 watts kind of makes me think it would not be enough. In RVs I have found that it runs full bore all the time Until the outside temp starts to get within about 5 -10 degrees of what I have my ac set to.

i hope the OP goes through with his build and leaves a bit of data behind for those of us who may follow with mini-spit builds.
 
chrisski said:
Thanks for these benchmarks.

I do estimate he could get a mini-split AC for the van that ran at 500 watts With an 8 k BTU unit if my other benchmark of an 8 k BTU and 500 watts I found is correct, but your 12 k BTU mini-split at 1200 watts kind of makes me think it would not be enough. In RVs I have found that it runs full bore all the time Until the outside temp starts to get within about 5 -10 degrees of what I have my ac set to.

i hope the OP goes through with his build and leaves a bit of data behind for those of us who may follow with mini-spit builds.
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To add to the benchmark, I have a 40ft charter bus conversion (not complete yet). It does run full bore all day and the very front and rear of the bus stay warmer during that time (the inside unit is mounted in the center of the bus in the "living area"). But it's enough to make it bearable (not an oven) and to keep the moisture out. Sitting in the living area is better than bearable.

With that said, I can put it in silent mode, and it will still keep the moisture out and will still keep the living area comfortable. The 1500W of used solar on the roof run it in this mode and still charge the battery. At night, the draw will shrink and shrink. I'll wake up in the morning to the largest loads being the mini fridge and chest freezer (when they're running), otherwise about a 2-3A draw on the batteries. I've boondocked for months managing the AC in this mode. It's a DIY Mr Cool minisplit 12k BTU. A few years down the road when the inverter warranty expires, I will upgrade to a 240v system and replace this unit with a dual internal unit 240v cassette. 15k BTU or larger. I will upgrade the solar and have a generator installed long before then.
 
My gosh you guy are a big help! I will go through with the 9000BTU mini split; it is the only way I can be sure that the batteries are kept at a reasonable temperature. Not to mention that I got awfully tired of sleeping in 91 degrees last Summer. I can't thank you enough.
 
guidecca said:
I wonder how to wire a second (24v) alternator. There must be guides somewhere.
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IMO adding a second alternator to a vehicle with the space not already in the compartment gets you to master fabricator level of skills.

I read about these additional second alternators and those seem like a huge headache to get it mounted and then find a belt that fits. I have a pickup. that has a space built for it since it was optional. Woud not be that hard for me since the parts would be over the counter. There’s an Ecoline van Ford makes from the same year with the same chassis and motor, but those vehicles are even harder to finnd any save in the engine compartment.
 
Just need a bracket, a new belt, and sometimes an idler pulley. Voltage is going to be too low for LiFePo4, but solar can top it off.
 
timselectric said:
Just need a bracket, a new belt, and sometimes an idler pulley. Voltage is going to be too low for LiFePo4, but solar can top it off.
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For the newer vehicles I see, its more of a place where to put it. Perhaps most vans and pickups come with the space for an optional second alternator.
 
Sometimes, you have to relocate the battery or air filter. If there's a will, there's a way. Specifically talking about trucks, vans, busses, and RV's.
These days, you can't leave a screwdriver in the engine compartment of a car. And, expect to be able to close the hood.
 
timselectric said:
Sometimes, you have to relocate the battery or air filter. If there's a will, there's a way. Specifically talking about trucks, vans, busses, and RV's.
These days, you can't leave a screwdriver in the engine compartment of a car. And, expect to be able to close the hood.
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On my style pickup, I’ve seen some creative ways to mount batteries. In the bed of the pickup. Even saw one mounted on the frame under the cab of the truck.
 
chrisski said:
On my style pickup, I’ve seen some creative ways to mount batteries. In the bed of the pickup. Even saw one mounted on the frame under the cab of the truck.
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Yup
Mine are located just inside the tailgate.
Didn't want to crawl on the ground, to add water. lol
 
guidecca said:
I wonder how to wire a second (24v) alternator. There must be guides somewhere.
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There's a lot of engineering obstacles to overcome here. Need a place to mount it, longer or separate belt to run it, possibly more pulleys...eh. Maybe my thoughts are over-complicating it, but it seems a lot more simple and less failure prone to replace the existing alternator with a high output one made to fit your van. Regardless, a fair place to start asking questions or doing research might be the mfg. They may have a catalogue of aftermarket parts or may be able to direct you to one.
 
DerpsyDoodler said:
There's a lot of engineering obstacles to overcome here. Need a place to mount it, longer or separate belt to run it, possibly more pulleys...eh. Maybe my thoughts are over-complicating it, but it seems a lot more simple and less failure prone to replace the existing alternator with a high output one made to fit your van. Regardless, a fair place to start asking questions or doing research might be the mfg. They may have a catalogue of aftermarket parts or may be able to direct you to one.
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I'm inclined to agree. I'm chipping away at the problem several directions and hoping one of them is safe and affordable. A second optional alternator, sources for solar panels that are smaller than 39" x 65", and a mini split that uses the least amount of electricity and fits in the comptroller's budget. It's all going to a good cause. Ford knows the answer; I'll be checking with them.
 
rcrracer said:
I've posted elsewhere the frequency range of inverter LG and Midea window ACs. They range from 10HZ to 120HZ. At 100 watts my Midea can produce a delta T of 12F. The max delta T I've seen is 24F at 750(?) watts. This is with auto fan speed. 100 watts would be cool out door temp. min fan speeds, 750 watts high outdoor temp, max fan speeds.
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I know this is an old thread but recently read an article on linear compressor tests. In that article 53Hz was the optimal efficiency point. On either side it drops off. But its still way more efficient that the stop/start of a conventional compressor. Seems the linear compressors have had some reliability issues. Not sure of the current reliability.
 
Altide8 said:
I am still trying to figure out how to work the unit properly and how to get it set up. (no real documentation) Although it is pulling about 380w on medium setting and fan on 3/5. The temp of the air coming out of the unit is about 40f.
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Just wondering what your results were on testing this unit. Did it meet your expectations?
 
diysolarforum.com

Under-Bench Mounted Heatpump for Running of Solar and clearing roof

Hello, I found this under bench mounted heatpump - it was released only in February 22. Pioneer® 9,000 BTU 115V Under-Bench RV Heat Pump Air Conditioner $1200 Summary- Cooling capacity: 9,000 BTU/H with 8.5 EER efficiency 8.8amp - 995 Watt Heating capacity: 9,000 BTU/H with 2.6 C.O.P...
diysolarforum.com diysolarforum.com

just FYI - I found a heatpump for Vans No idea about the power draw
 
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