Upgrade Solar PV with batteries (UK) or? - Update: new Aircon not working - Page 1
Forum section: electronics / general

author: IanJ
author_rank: Unknown
timestamp: August 18, 2022, 07:34:22 pm
content: Hi all,I'm in the UK, NE Scotland to be more precise and am looking to upgrade our 4kW Solar PV system.The idea is that I want to run my air-con/heater system in my workshop 24/7 and 365 days a year. If I did that right now my energy usage would go through the roof. The workshop is a converted standalone garage (fully insulated etc).In summer the air-con (800W) battles to keep the workshop cool. In winter I have a 500W heater which likewise would be on quite a bit, especially at night.So........I have been looking at a 5kWh grid tied battery system (AC type) that would be simple to fit......the problem, I think, is that in the winter months there wouldn't be much sun around to have the Solar PV system charge the batteries and I don't really want to have the grid charge the batteries......energy prices are huge right now, albeit maybe I am being too picky.I am also playing with the idea of an off-grid 1kW or 2kW Solar PV system, with batteries, on the workshop roof......just to power the air-con and heater......but thats a heck of expense not to get any benefit to the rest of the household.Any UK folks out there that have been down this road.........that can share experiences.Ian.

author: Monkeh
author_rank: Super Contributor
timestamp: August 18, 2022, 07:37:07 pm
content: Quote from: IanJ on August 18, 2022, 07:34:22 pmI seem to recall you have a portable unit - is it the usual single-hose type which uses room air to cool the condenser?

author: IanJ
author_rank: Unknown
timestamp: August 18, 2022, 08:33:11 pm
content: Quote from: Monkeh on August 18, 2022, 07:37:07 pmIt is indeed, and the exhaust vent i have ducted outside through a wall vent.Have been looking at replacing with a split AC type, but they are bigger and 2.5kW minimum which is overkill for my tiny workshop.Should have said also.....have been looking at a wind turbine system, say 1kW but the local authorities are having it.......yet!Ian.

author: Monkeh
author_rank: Super Contributor
timestamp: August 18, 2022, 08:39:03 pm
content: Quote from: IanJ on August 18, 2022, 08:33:11 pmCheck whether you're looking at cooling power or input power - 800W I think will be around a 6000BTU unit, and both 6 and 9k are available in mini-splits. Your current unit is sucking hot air in all day, which is a massive problem.

author: jc101
author_rank: Frequent Contributor
timestamp: August 18, 2022, 09:00:40 pm
content: I had a small Daikin split AC/Heat pump installed into my office/workshop back in 2016. Cooling capicty is 2kW and heating 2.5kW with a nominal COP of 4.7 or so. I leave it on 24/7 and it doesn't take much power. I can control it from an app, check temps etc. too, which is handy. From a recent service, on full heat, it was pulling ~650W, which it doesn't need to do for long to heat up the office. Most of the time the fan is running on the inside unit and the outdoor unit just clicks in and out as needed to maintain a stable temperature. Takes very little power the rest of the time, and it's so quiet compared to a standalone unit. Pulls a lot of moisture out too, which drains externally do no tanks to empty.The indoor unit is small and up on a wall, the outdoor unit isn't large either.The total installed cost was £1,260 or with the 5% VAT £1,512. A heat pump attracts 5% VAT rather than 20%.

author: Marco
author_rank: Super Contributor
timestamp: August 18, 2022, 09:12:14 pm
content: Quote from: IanJ on August 18, 2022, 08:33:11 pmIt's a shame the US style window air conditioners have no real market here. Makes more noise because of the unbalanced external fan sloshing water on the condenser, but can be made dirt cheap, also wouldn't need to violate the law like when installing a mini split. Can get a Samsung mini split for 500 Euro though, so maybe time for some law breaking?

author: IanJ
author_rank: Unknown
timestamp: August 18, 2022, 09:19:06 pm
content: Quote from: jc101 on August 18, 2022, 09:00:40 pmThanks, that sounds pretty good. I'll take a look at them.Ian.

author: jc101
author_rank: Frequent Contributor
timestamp: August 18, 2022, 09:20:34 pm
content: Quote from: IanJI’ll get the part number and a couple of pics tomorrow.

author: IanJ
author_rank: Unknown
timestamp: August 22, 2022, 08:41:37 pm
content: Hi all,Got quoted £1.9k + VAT fitted for a 2kW Daikin RXP20 / FTXP20 aircon/heater unit.Was about what I thought it would be. Aberdeen, Scotland is kinda expensive.Ian.

author: Marco
author_rank: Super Contributor
timestamp: August 22, 2022, 08:45:04 pm
content: With that kind of delta compared to a cheaper "illegal" option, I'd go for the illegal DIY option with a lower cost minisplit.It's not like LG or Samsung are entirely untrustworthy brands.

author: Monkeh
author_rank: Super Contributor
timestamp: August 22, 2022, 08:45:38 pm
content: It'll be substantially cheaper to run and more effective than what you have. If you're willing to buy a vacuum pump and stretch the law a little, you could fit your own for under a grand.

author: NiHaoMike
author_rank: Super Contributor
timestamp: August 23, 2022, 12:42:47 am
content: Quote from: IanJ on August 18, 2022, 08:33:11 pmTry turning it into a 2 duct unit by adding a second duct going to the condenser.

author: Marco
author_rank: Super Contributor
timestamp: August 23, 2022, 01:06:38 am
content: I think not all mobile air conditioner are internally completely air tight between condenser and evaporator section, so might need a bit more modding than just boxing up the intake and adding a second hose.If you want to stay within the law, a through wall/window aircon is still a possible solution. They are twice as expensive here as in the US and a little noisier, but they do cool well.

author: IanJ
author_rank: Unknown
timestamp: August 23, 2022, 02:33:31 pm
content: Hi all,Modding the existing unit not really an option (although would be fun!) since it's kinda noisy (a pain when filming videos) as it is and doesn't quite have the cooling ability (albeit modding may help this), and it takes up a bit too much room in my small workshop.The current setup is hacked to death and is run by a VB app I wrote (the separate heater also)......so will be good to see the back of that!This new one will be cheaper to run and will cover me if and when i do the small workshop extension I am planning in a couple of years.Looks like I'll go ahead with this new one........Ian.

author: nctnico
author_rank: Super Contributor
timestamp: August 23, 2022, 03:46:43 pm
content: Quote from: Monkeh on August 22, 2022, 08:45:38 pmIndeed. I installed a new split A/C in my home last year by myself. I choose for Panasonic because they have the lowest noise (both indoor and outdoor units) and all service and installation documentation can be found online.I bought the piping cut to length complete with flares (getting the flares done properly requires an expensive tool and experience). Then I needed some tooling: I got a vacuum pump (Aliexpress), torque wrenches (Aliexpress), Nylog Blue sealant for refridgerator piping (Ebay) and leak detecting liquid (local shop). The only thing I didn't do was pressure test the system. The Nylog Blue sealant and using torque wrenches are my ticket to make sure there where no leaks.I sold all the 'tooling' except the torque wrenches and even made a little bit of money from it.This is my third aircon. I started with a mobile unit but that made way too much noise to work next to and it didn't cool at all. The 2nd one is a split unit with a connector between the pipes. Unfortunately these are not longer available on good quality, low noise units.

author: f4eru
author_rank: Super Contributor
timestamp: August 28, 2022, 07:46:42 pm
content: QuoteI would argue : instead of trying to do that on batteries, which is difficult to impossible (achieve 80% uptime is much easier)Better to invest into improved insulation, and then oversize the A/C unit to use the interior temp as day/night as thermal buffer, i.e. run the A/C only when solar is available.

author: IanJ
author_rank: Unknown
timestamp: September 01, 2022, 04:25:05 am
content: Hi all,Update:A new 2kW Daikin split A/C was installed yesterday and i've set it up in AUTO mode 24/7 and running it in it's ECON mode and at a low power setting and its cooling and heating just great to maintain my requested 23.0degC.It's certainly got more ooomph than my last portable unit, and it's also dead quiet both the inside and outside units.I am measuring the consumption, logging temps etc so we'll see how it performs as I explore the various modes and settings.For now, my 3458A is a happy 8.5digit DMM.Ian.

author: IanJ
author_rank: Unknown
timestamp: September 02, 2022, 06:49:44 am
content: Hi all,Oh dear!.......my workshop isn't happy!......there is a problem with my new AC.Works fine, and i have it in AUTO mode all the time regulating 23degC which it does.But running like this for a few hours it eventually will start to drop the room in temp slowly over a couple of hours, still switching between cool and heat mode but just as if the user had started to lower the setpoint temp.Once it is down by a few degC it suddenly starts throwing out heat.......the first time it did that i never noticed till i went out in the morning to see the workshop at 29degC.I switched the aircon off at the remote, waited 5 secs and then on again and it immediately started throwing out cold air and brought the room back to 23degC.I had logged the workshop temp independantly so i know the exact sequence of events.Its done this 2 nights in a row......so today i'll run it first thing in the morning and right through. Piccy attached of my log from the first night.Software fault?Temp sensor issue in the inside unit?No errors, unit always reporting its still in AUTO mode.There is a wifi kit avail which i will try to get which will let me know what the aircon thinks the workshop temp is.Installer is contacting the factory techs for advice, i sent him photos of the log graph showing the time line temps.Ian.

author: jc101
author_rank: Frequent Contributor
timestamp: September 02, 2022, 08:05:46 am
content: Over the summer I tend to leave mine on cool mode. The insulation and heat generated by some kit which is on 24/7 provides keeps the status quo. Winter I tend to leave it on auto, so it tops up with heat when needed but when I’m in there too with more gear on it may flip to cooling. I have it on the mode where heating points down and cooling points horizontal/up, comfort mode I think.As the temp sensor is inside the indoor unit is only senses the air pulled back to it. As my roof slopes a little I have found the hot air sits there. Solved with an old 120mm PC fan on a shelf to stir up the air and send it back to the indoor unit. Can’t hear it running, it’s just enough to mix the air up.it can hunt in auto mode, I have a vague memory about a asking about a remote temp probe. Even it is was just one outside the indoor unit. I’d have to dig back through my email archive to see if I can find that.

author: IanJ
author_rank: Unknown
timestamp: September 02, 2022, 08:20:53 am
content: I have asked the installer for a remote sensor. My unit is 70mm from the workshop roof only, so may be an issue.....albeit at 29degC that first moring it should have sensed that.Ian.

author: jc101
author_rank: Frequent Contributor
timestamp: September 02, 2022, 08:32:37 am
content: Mine is close to the ceiling as well, you can see the slope in this pic too.Doesn't ECON mode slow the fan speed down? I leave mine on auto fan, which seems to be optimal for me.

author: IanJ
author_rank: Unknown
timestamp: September 02, 2022, 08:46:04 am
content: ECONO mode uses less power, I think it's about a 3rd less or something.I have the FAN setting at minimum. My workshop is very small, doesn't take minutes to get to temp (up or down).Ian.

author: jc101
author_rank: Frequent Contributor
timestamp: September 02, 2022, 08:52:25 am
content: Mine is ~3m x 3.8m, I’d try the fan higher when you’re not in there. Just general moving about will stir the air up. When you’re not there, maybe a bit more movement would help mix the air and improve things.

author: IanJ
author_rank: Unknown
timestamp: September 02, 2022, 09:10:49 am
content: Quote from: jc101 on September 02, 2022, 08:52:25 amAhhh, good idea!Update: Installer going to fit a remote temp sensor and a Wifi adaptor.Ian.

author: IanJ
author_rank: Unknown
timestamp: September 05, 2022, 10:03:32 am
content: Update:Looks like Eng. has fixed my aircon.........cavity where pipes n cables went through the wall wasn't sealed so was getting a cold draft......and the internal temp sensor isn't very far away from the cavity!Ian.

author: IanJ
author_rank: Unknown
timestamp: September 05, 2022, 08:45:49 pm
content: Update:When your new Daikin air-con has a bit too much built in hysteresis around the temp setpoints.....what do you do?You write your own.......working!Actually, I modified my old control system, dropped the old cooler/radiator subs and managed to get http requests to work via wifi with my Daikin.Ian.

author: jc101
author_rank: Frequent Contributor
timestamp: September 06, 2022, 08:03:39 am
content: Quote from: IanJ on September 05, 2022, 08:45:49 pmWell this is interesting news, I didn't know the WiFi module supported direct access via http

author: IanJ
author_rank: Unknown
timestamp: September 06, 2022, 04:30:43 pm
content: Quote from: jc101 on September 06, 2022, 08:03:39 amI can't remember the site offhand.......but here's the basics:Code:READ:http://192.168.1.231/aircon/get_control_infoSET:http://192.168.1.231/aircon/set_control_info?pow=1&mode=1&stemp=24&shum=0&f_rate=B&f_dir=3pow = 1ONpow = 0OFFmode = 0, 1, 7AUTOmode = 2DEHUMIDmode = 3COLDmode = 4HOTmode = 6FANstemp=Range of numbers: AUTO 18-31, HOT 10-31, COLD 18-33f_rateA auto, B silence, 3 lvl_1, 4 lvl_2, 5 lvl_3, 6 lvl_4, 7 lvl_5shum0f_dir0 wings stopped1 wings vertical motion2 wings horizontal motion3 wings both motionThese are the mandatory parameters that must go with every request, even power off:- `pow`- `mode`- `stemp`- `shum`- `f_rate`- `f_dir`http://192.168.1.231/aircon/set_control_info?pow=1&mode=3&stemp=20&shum=0&f_rate=3&f_dir=3ONCOLD modetemp = 20hum = 0fan rate = 3f_dir = 3http://192.168.1.231/aircon/set_control_info?pow=1&mode=4&stemp=25&shum=0&f_rate=3&f_dir=3ONHOT modetemp = 25hum = 0fan rate = 3f_dir = 3Update:Here's the aircon running for a while with the software control, the graph demonstrates the low amount of hysterisis......just perfect for a wee metrology/repair/production workshop.Since the photo, I added controls for the Fan Rate and Fan Direction.