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hvac:solar_ac [2023/08/28 03:15] princess_fluffypants [I am rich, foolheardy, or both, and want to run A/C off of solar] |
hvac:solar_ac [2024/02/05 14:25] (current) princess_fluffypants [12v/24v/48v DC Units] |
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====== Running A/C off solar ====== | ====== Running A/C off solar ====== | ||
- | **TL;DR - It is technically | + | **TL;DR - It is technically |
- | More expensive than the A/C system itself is everything you'll need to power it. A/C takes a //huge// amount of electricity; | + | More expensive than the A/C system itself is everything you'll need to power it. A/C takes a //huge// amount of electricity; |
- | And it's still not going to give great results; it might be okay for taking the edge off on a very hot day (bringing the inside of the van down to 80f while the exterior temperatures are over 95f), but you're not going to be able to keep the van at 68 degrees on a hot day just off of solar. | + | If you are reading this you probably haven' |
- | + | ||
- | Especially because (rather paradoxically) running A/C off of solar requires that you park your van in the sun; which means the inside of the van will get //MUCH// hotter than it would if you simply parked in the shade. This puts you in a weird catch-22 where you can't run the A/C without parking in the sun, but parking in the sun means you have to run the A/C much harder than your solar can sometimes keep up with. | + | |
- | + | ||
- | ===== Running A/C off of shore power ===== | + | |
- | + | ||
- | This is quite practical, and it's how RVs have been doing it for many years. The A/C systems run natively on 120v AC(Alternating Current) units and are getting power from a [[electrical: | + | |
- | + | ||
- | See [[https:// | + | |
- | ===== I am rich, foolheardy, or both, and want to run A/C off of solar ===== | + | |
- | + | ||
- | Don't say we didn't warn you. If you are reading this you probably haven' | + | |
* How much power it takes to run the A/C unit continuously | * How much power it takes to run the A/C unit continuously | ||
- | * Even the most efficient 12v A/C units draw upwards of 60 amps at full blast; that's over 700w. That will drain even the most massive | + | * Even the most efficient 12v A/C units draw upwards of 60 amps at full blast; that's over 700w, // |
* Using a 120v system through an inverter will increase that power draw even more. | * Using a 120v system through an inverter will increase that power draw even more. | ||
- | * how much power it takes to //start// the A/C unit (Usually a lot more) | + | * How much power it takes to //start// the A/C unit (Usually a lot more) |
* Some units have a "soft start" function, using a bunch of capacitors to help the compressor start while smoothing out the massive spike in current draw | * Some units have a "soft start" function, using a bunch of capacitors to help the compressor start while smoothing out the massive spike in current draw | ||
- | * how much [[electrical: | + | * How much [[electrical: |
* If it's hot enough to run A/C it's hot enough that you are already losing 25% of your solar panels' | * If it's hot enough to run A/C it's hot enough that you are already losing 25% of your solar panels' | ||
- | * In order to generate 700w of power to run an average system, you'll need 1200w worth of panels. And that's //just to run the A/C//. That's not giving you any overhead to charge your batteries or do anything else. | + | * In order to generate 700w of power to run an average system, you'll need at least 1200w worth of panels. And that's //just to run the A/C unit itself//. That's not giving you any overhead to charge your batteries or do anything else. |
- | * how much space those panels will require | + | * How much space those panels will require |
- | * how much money those panels will cost | + | * How much money those panels will cost |
- | * how much money big [[electrical: | + | * How much money big [[electrical: |
+ | * How much money you will spend on the massive runs of finger-thick copper cabling to connect it all together | ||
And that's just considering running the unit in optimum solar conditions in the daytime. | And that's just considering running the unit in optimum solar conditions in the daytime. | ||
+ | And it's still not going to give great results; it might be okay for taking the edge off on a very hot day (bringing the inside of the van down to 80f while the exterior temperatures are over 95f), but you're not going to be able to keep the van at 68 degrees on a hot day just off of solar. | ||
- | There is a reason people [[camping: | + | Especially because |
+ | ---- | ||
- | One exception to this dilemma is available if you live in the desert; [[hvac: | ||
+ | ===== Running A/C off of shore power ===== | ||
- | ===== But some people are doing it! ===== | + | This is very practical, and it's how RVs have been doing it for many years. The A/C systems run natively on 120v AC(Alternating Current) and are getting power from a [[electrical: |
- | That's right. | + | 120v AC units are vastly more common, and much cheaper than the 12v or 24v DC units. These are usually roof-mounted, |
- | There are people with an in-depth understanding of the issues, and the money and space to make it happen. It does not stand to reason that the average person with average resources and commitment will make the trip from idea to implementation. | + | See [[https:// |
- | 12v/24v/48v DC units do exist and can give some efficiency gains as you don't need to run them through an inverter, but they are very expensive. All-in-one roof units offer a much simpler installation and are usually around $2,000; Dometic has their [[https:// | + | ---- |
- | Beginning in about 2023, cheap Chinese 12v mini-split systems have started to come down to almost acceptable prices ($1k in the USA, or as little as $500 if you can wait the 1-2 months for shipping from China). Reports | + | ===== But I saw someone |
- | 120v roof-mounted A/C units can be had for as little as $500 and are very common in the rest of the R/V world, so if you can find a big enough inverter it can be cheaper to go that route. | + | The things |
- | If you would like to learn more about how it's been done before, start with [[http:// | + | - Rich people with extremely expensive vans that they paid professionals |
+ | - " | ||
+ | - Completely faked and just being shared around to generate views | ||
+ | - All of the above. | ||
+ | There is an extremely small subset of people who have successfully installed A/C in their own van, and been able to use it off-grid for extended periods of time. They are people with an in-depth understanding of the issues and the money and space to make it happen. It does not stand to reason that the average person with average resources and commitment will make the trip from idea to implementation. | ||
+ | |||
+ | There is a reason that most people [[camping: | ||
+ | |||
+ | ---- | ||
+ | ===== I am rich, foolheardy, or both, and still want to run A/C off of solar ===== | ||
+ | |||
+ | Don't say we didn't warn you, but here's some links to people who have done it successfully. Start with [[http:// | ||
+ | |||
+ | * [[https:// | ||
+ | * [[https:// | ||
* [[https:// | * [[https:// | ||
* [[https:// | * [[https:// | ||
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* [[https:// | * [[https:// | ||
* [[https:// | * [[https:// | ||
- | | + | |
- | * [[https:// | + | |
Also see | Also see | ||
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* [[https:// | * [[https:// | ||
- | ===== But RVs are doing it! ===== | + | ---- |
+ | |||
+ | ==== 12v/24v/48v DC Units ==== | ||
+ | |||
+ | AC Units that can operate directly on DC current off of your house batteries give some efficiency gains as you don't need to run them through an inverter, but they are very expensive. Higher voltage systems allow you to use much thinner cables for power, which can be a significant cost savings over longer runs. | ||
+ | |||
+ | **All-in-one roof units** offer a much simpler installation and are usually around $2,500; Dometic has their [[https:// | ||
- | Commercial RVs and travel trailers typically power their single A/C off 30A (3,600W) [[electrical:shore_power|shore power]], and sometimes can't run that and a MW at the same time depending on other loads. Dual A/C typically runs off 50A (12,000W) shore power. | + | **Split units** separate the evaporator/condenser/ |
- | When away from shore power they run generator power into the shore power port. | + | Beginning in about 2023, cheap Chinese 12v mini-split systems have started to come down to almost acceptable prices ($1k in the USA, or less if you can wait the 1-2 months for shipping |