Switching to a compressor type Refer…
Bunkysdad
Registered Users Posts: 38 ✭✭
My truck camper is now up to 560w mppt solar and with two 200a/hr LFP batteries…Considering swapping out our 6 c/f Norcold refer with a 8.1 c/f Danfoss-Secop compressor-type refer rated nominally at 5.23 amps (so say, 125a/hrs over a 24 hr period)…Harvest under ‘ideal conditions’ might even be around 34-35 amps, but (per BattleBorn estimates) about a 3.75 amp hourly average over an 8hr harvest period, per each 100w panel, thus 168 net averaged recovered a/hrs…
Question here is, just wondering what experiences others might have had when using a compressor type refer??
Question here is, just wondering what experiences others might have had when using a compressor type refer??
Thanks, Bunkysdad
Comments
-
Oops, (oddly, I don’t see an edit button?..), Imeant 240 net averaged amps instead of the aforementioned 168…Hope I got this right…
-
Sorry, Upon re-re-re-review, 168 net averaged a/hrs…sorry for me dummy
-
You should see a "black gear" button to top right of post--You can edit clicking here".
What you really want to know is how many Watt*Hours or Amp*Hour (@ 12 or 24 volts) uses per day.
https://norcold.com/product/norcold-nrf-60-portable-refrigerator/ (???)
For example, say the fridge (compressor type) uses 5.3 Amp*Hours and guess that it has a 50% duty cycle in "normal" operation:- 5.3 AH * 24 hours per day * 0.50 duty cycle = 63.6 AH per day (guess)
- 63.6 AH per day * 12 volts = 763 WH per day
For your setup, guessing Carson City Nevada, fixed array, mounted flat to roof:
http://www.solarelectricityhandbook.com/solar-irradiance.htmlCarson City
Measured in kWh/m2/day onto a horizontal surface:
Average Solar Insolation figures
Say use camper Feb-October:Jan Feb Mar Apr May Jun 2.29
3.15
4.61
5.85
7.01
7.77
Jul Aug Sep Oct Nov Dec 7.76
6.89
5.60
4.06
2.60
2.11
- 560 Watt array * 0.77 off grid DC Li Ion system * 3.15 Hours of sun per day = 1,358 WH per day (February "break even")
- 1,358 WH per day harvest / 12 volt battery bank = 113 AH per day
- 1358 WH per day * 0.65 "base load fudge factor" = 882.7 WH per day for "base loads"
https://www.amazon.com/s?k=dc+digital+amp+volt+energy+meter&crid=25P8P1GNKJVVX
Also, ventilation around the fridge is important... Above 85F ambient, many refrigerator/freezers tend to "have issues". And they also take more energy to cool.
Your thoughts?
-Bill
Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset -
I think Bill's 50% duty cycle is reasonable, or a bit conservative. For comparison, I have a 4.4 CF Novakool. I turned the compressor down to the lowest speed & it takes about 2.2 amps, & very roughly 50% DC. From end of charging, to start of charging I might be down 20-30 ah. This time of year that's about 16 hours. The heater probly takes about 5 - 10 ah.In hot weather 90F+, even with the compressor speed turned down, it keeps up, but duty cycle is probly approaching 100%I have no trouble keeping up with this with 350W solar.I'm going to be in Moab in mid March, I should keep closer track of consumption.
-
Wow, Sorry for my delayed response (sidetracked by projects and life - lol) but this is some terrific data, especially the calc methodology, as well as the valuable ‘real world’ testament !! Awesome!Update, I’ve since added another 100w panel (for a new total of 660w), but have not yet quite decided on the refer swap because of a unanticipated longer pay-back period due now to costlier fuel and likely fewer camping excursions, but nevertheless still actively considering!!Many Thanks to All!!
-
Hey Bill, upon a re-read, just curious what is meant by 0.77 dc lithium? - is this a kinda presumed LiFePO4 efficiency??
please clarify…Thanks -
Bunkysdad,
I am assuming the Li Ion batteries are pretty much 100% efficient. The 0.77 is the derating of the solar panels and charge controller efficiency.- 0.81 panel derating (hot panels, Vmp falls and MPPT output drops or using PWM controller) * 0.95 charge controller efficiency = 0.77 overall efficiency
On a hot summer day under full sun, the cells can be upwards 40C over ambient.
MPPT (maximum power point tracking) charge controllers basically follow the equation:- Power to Battery = Vmp * Imp * 0.95 controller efficiency
https://www.solar-electric.com/solarland-slp100-12u-100-watt-12-volt-solar-panel.html
Maximum power (Pmax): 100 WattsNominal voltage: 12 Volts DCVoltage at Pmax (Vmp): 17.2 Volts DCCurrent at Pmax (Imp): 5.81 Amps DCOpen-circuit voltage (Voc): 21.6 Volts DCShort-circuit current (Isc): 6.46 Amps DCPower tolerance: +/- 5%
As long as Vmp is over Vbatt--Then Imp (current from solar panel) is passed to battery:- 5.81 Amps Imp * 14.5 volts charging = 84 Watts
- 84 Watts actual / 100 Watts Pmp = 0.84 "derating" for panels
- 0.84 panel derating (on PWM) * 0.95 Controller eff = 0.80 over all system eff
-Bill
Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset -
Many Thanks Bill for the very detailed and revealing answer!!…Upon the first cut, it’ll likely take me a bit to fully wrap my mind around it, but you’ve shared some truly rational and invaluable information Sir, I appreciate your fine tutelage !!Bunkysdad
-
You are very welcome Bunkysdad,
Feel free to ask more questions as they come up.
Take care,
-BillNear San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
Categories
- All Categories
- 220 Forum & Website
- 128 Solar Forum News and Announcements
- 1.3K Solar News, Reviews, & Product Announcements
- 189 Solar Information links & sources, event announcements
- 885 Solar Product Reviews & Opinions
- 254 Solar Skeptics, Hype, & Scams Corner
- 22.3K Solar Electric Power, Wind Power & Balance of System
- 3.5K General Solar Power Topics
- 6.7K Solar Beginners Corner
- 1K PV Installers Forum - NEC, Wiring, Installation
- 2K Advanced Solar Electric Technical Forum
- 5.5K Off Grid Solar & Battery Systems
- 424 Caravan, Recreational Vehicle, and Marine Power Systems
- 1.1K Grid Tie and Grid Interactive Systems
- 651 Solar Water Pumping
- 815 Wind Power Generation
- 621 Energy Use & Conservation
- 606 Discussion Forums/Café
- 300 In the Weeds--Member's Choice
- 74 Construction
- 124 New Battery Technologies
- 108 Old Battery Tech Discussions
- 3.8K Solar News - Automatic Feed
- 3.8K Solar Energy News RSS Feed