EcoRenovator  

Go Back   EcoRenovator > Improvements > Geothermal & Heat Pumps
Advanced Search
 


Blog Register 60+ Home Energy Saving Tips Recent Posts Search Today's Posts Mark Forums Read


Reply
 
LinkBack Thread Tools Display Modes
Old 07-25-18, 11:50 PM   #1
Lurking Renovator
 
Join Date: Jul 2018
Location: Masterton
Posts: 7
Thanks: 1
Thanked 0 Times in 0 Posts
Default Excess solar power to run compressor

Hi All,

Anyone know of a method of controlling an AC compressor to utilise excess solar power? I essentially want to control the compressor using a VFD or other form of speed controller but im not sure what types of compressors are available that can be controlled in this fashion.
What I would ideally want to do is purchase an external unit from a heat pump / split air conditioner (common in NZ) and convert it. Many of these units are "inverters" and control the compressor speed and output based on the temperature of a room. Does anyone know if the singling to the controls of such a unit can be intercepted and controlled say by a 0-10v or frequency input.
I would also like to replace the inside unit of such a setup with a refrigerant / water exchanger to use output to heat our under floor heating system.
Im new to refrigeration so am not sure on the specifics of this kind of system but I do have a grasp of PLC and Arduino control from previous projects.

I would have thought that systems on the market should have this function but im unable to find any examples of this. It would seem as tho a heat pump domestic Hot Water heater would also be a good application for this type of control.

Thanks for reading. Any input is greatly appreciated.

MikeC

nzmikec is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote
Old 07-29-18, 09:08 AM   #2
Helper EcoRenovator
 
Join Date: Dec 2015
Location: New Mexico/Texas
Posts: 43
Thanks: 16
Thanked 5 Times in 5 Posts
Default

Lennox makes some AC/heat pumps that are specifically designed to connect to solar. I think it's a great idea but not so useful for those of us who already have an AC unit. It's nice because you don't have to go through the grid connection bureaucracy.

https://www.lennox.com/products/heat...ng/solar-ready
ME_Andy is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote
Old 07-29-18, 12:15 PM   #3
Helper EcoRenovator
 
Join Date: Dec 2015
Location: New Mexico/Texas
Posts: 43
Thanks: 16
Thanked 5 Times in 5 Posts
Default

I guess I'm confused about wanting to run the AC while heating the floor.
ME_Andy is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote
Old 07-29-18, 05:22 PM   #4
Lurking Renovator
 
Join Date: Jul 2018
Location: Masterton
Posts: 7
Thanks: 1
Thanked 0 Times in 0 Posts
Default

Hi Andy,
I dont want to run an AC on cooling while heating the floor. Just want to use a heatpump powered by excess solar. Basically I want to control the compressor to match the excess solar power available. Cheers.
nzmikec is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote
Old 07-29-18, 07:06 PM   #5
Supreme EcoRenovator
 
Join Date: Jan 2010
Location: elizabethtown, ky, USA
Posts: 2,217
Thanks: 321
Thanked 557 Times in 466 Posts
Send a message via Yahoo to jeff5may
Default

Keywords DC brushless inverter compressor

You have to elaborate on the existing solar pv system to get a worthwhile answer. Not knowing what you have or how much extra capacity you have available makes it hard to recommend anything specific. Grid tied system? Battery bank? Solar thermal? None of the above? Hmmm....

Last edited by jeff5may; 07-29-18 at 08:39 PM..
jeff5may is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote
Old 07-30-18, 02:04 AM   #6
Lurking Renovator
 
Join Date: Jul 2018
Location: Masterton
Posts: 7
Thanks: 1
Thanked 0 Times in 0 Posts
Default

Thanks for the reply guys.

Currently we are planning the build but the solar system will be very similar to what we currently have being a 3kw grid tied SMA system. I am using EmonCMS and openenergymonitor CT hardware to monitor power produced and our grid import / export. Im currently using a diverter that measures the grid connection and runs an immersion heater to heat our water in a tank. (some kind of leading or trailing phase power control to "throttle" the resistive load)

Im pretty happy modifying / hacking things to a point. Ideally I could find a common compressor that is 3 phase an can be run with a 1 phase to 3 phase VFD or a "mini split" outdoor heat pump that I could add a heat exchanger to heat water and use the existing inbuilt inverter in the unit and talk to it via the existing controls that would have been attached to the indoor unit?

I dont understand why this is a new problem? Surely in hot environments people have solar installed and want to match the output of AC to the power produced?

Thanks for taking your time and replying to my thread.
nzmikec is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote
Old 07-30-18, 12:57 PM   #7
Helper EcoRenovator
 
Join Date: Mar 2018
Location: Rustbelt, USA
Posts: 55
Thanks: 0
Thanked 1 Time in 1 Post
Default

I imagine there are very few people who want to match their AC output to solar output. 99.999% of the market wants their AC output to match the thermal load.

I could see it in a utility scale application for load shedding/demand control, but there they would simply switch batches of units on/off rather than scale up/down the individual unit outputs.

take a look at ice energy's ICE BEAR units in California. the utility can turn them on/off of compressor operation to shift demand to suit the grid. the end user still gets thermostat controlled AC.

now if you were doing energy storage, i could see using a a VFD 0-10V input based on solar output to avoid needing large batteries. but as for on-demand operation, instantaneous solar conditions are not typically the demand metric.

someone on here has a thread for a VFD driven 3 phase 3 or 5 ton water to water unit. i believe it ramps down to match the load/motor ratings. you could take that logic and add on a demand variable, secondary to the needs of the mechanical/electrical requirements.
u3b3rg33k is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote
Old 07-31-18, 11:49 PM   #8
Supreme EcoRenovator
 
Join Date: Jan 2010
Location: elizabethtown, ky, USA
Posts: 2,217
Thanks: 321
Thanked 557 Times in 466 Posts
Send a message via Yahoo to jeff5may
Default

You don't need a super complicated rig to do what you desire. Sure you can use a complicated speed control driving an industrial compressor, but why? It doesn't do more, it just costs more. Just modify an existing outdoor unit. Having a grid tie just makes it easier.

The main concern or three in your unique system would be:

Domestic hot water or space heater duty
Amount of excess electrical power
Direct DC operation from pv panels or tied to ac mains power / inverter
jeff5may is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote
Old 08-01-18, 01:49 AM   #9
Lurking Renovator
 
Join Date: Jul 2018
Location: Masterton
Posts: 7
Thanks: 1
Thanked 0 Times in 0 Posts
Default

Thanks Jeff,

I would love to find an existing outdoor unit to modify however im still unsure on how I can control the compressor speed and therefore the power consumption. Are the units that specify they are an "inverter" DC or three phase to achieve the speed control? What kind of signalling or control does the outdoor unit receive to control the speed?
nzmikec is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote
Old 08-01-18, 07:52 AM   #10
Supreme EcoRenovator
 
Join Date: Jan 2010
Location: elizabethtown, ky, USA
Posts: 2,217
Thanks: 321
Thanked 557 Times in 466 Posts
Send a message via Yahoo to jeff5may
Default

Yes, the units that have variable capacity are "premuim" machines in the products offered, and the manufacturers of these units are very proud of them. The boasting is inflated and claimed ratings are highlighted by every sales pitch. These things have been around for over a decade now, so the various manufacturers have developed lines of machines that have fancy names to designate the added functionality. There are also a lot of these types of systems on the second hand market and in the salvage industry available for a lot less than retail price.

Not knowing your operating needs, I will be very general in describing what is available. Also, due to your backwards system goal (matching the source instead of the load), you're probably not going to find a manufactured unit that will suit you. The source matching interface is going to be non-existent. It will need to be built by you or someone who serves you.

Ok, so choosing a suitable outdoor unit, you have 2 major criteria to consider: capacity and method of modulation. There are a bazillion different units on the market and they are all classified to serve specific purposes. In the variable capacity domain, there are 4 main types of systems. Take a look at this table drawn up by Emerson:

Using this chart should help you decide which method of modulation to employ to meet your specific purposes.

As you can see, the capacity range begins around 2 or 3 tons. This is because all of the makers of HVAC equipment consider anything smaller a "novelty" item. Minisplit systems are a prime example of this. They don't sell a huge number of these systems compared to the larger capacity machines, and even more so with variable capacity setups.

By capacity, they classify anything 2 to 5 ton as residential and anything over 5 ton as commercial. These 2 classes account for 90 percent or better of the corporate revenue stream. As a result, the small, modulating capacity units are pretty much sold as "what you see is what you get" packages with almost non-existent support except for installation instructions. Even if you buy new, don't expect any help from the store or manufacturers, especially if you aren't an authorized dealer. Even they don't get much help.

Attached Thumbnails
screenshot_20180801-075318-jpg  
jeff5may is offline  
Digg this Post!Add Post to del.icio.usBookmark Post in TechnoratiTweet this Post!
Reply With Quote
Reply


Tags
arduino, controller, solar, vfd

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On



All times are GMT -5. The time now is 04:33 PM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2018, vBulletin Solutions Inc.
Content Relevant URLs by vBSEO
Ad Management by RedTyger
Inactive Reminders By Icora Web Design