Normal output in hot days?

Discussion about OutBack Inverters in Grid Tie Applications

Moderators: OutBack, OutBack Moderator Team

Normal output in hot days?

Postby Shadow_Storm56 on Sun Jun 09, 2019 2:08 pm

I have always wondered if I have an issue or it is just normal but I always lose alot of power when it gets hot out. Both arrays combined will do 4300W total and the max I will get on a moderate hot day is 3.6. The max on a peak summer heat would be 3-3.2. Is it normal for it to drop that badly in high heat, it basically works out that Sunny summer day or sunny winter day I get the same total. More output in winter but shorter days. One array is made up of all the same panels and is free standing so lots of air around it, it cannot go up to the optimal tilt for peak of summer but gets 3/4 of the way there. The other array is perfect angle but is partly made of lower quality panels so it I would expect more losses. Mainly the larger array I'm surprised drops down from 2300 to around 1700-1800 on hot days
Shadow_Storm56
Forum Guru
 
Posts: 148
Joined: Thu Aug 02, 2018 8:29 pm
My RE system: Solar panels, charge controllers , outback radian inverter.

Re: Normal output in hot days?

Postby raysun on Sun Jun 09, 2019 4:09 pm

Heat does funny things to PV panels. As temperature rises, output current increases exponentially, and voltage decreases linearly. Net effect is reduction in output efficiency from 10-25%.
raysun
Forum Czar
 
Posts: 623
Joined: Tue Jul 26, 2016 5:57 am
My RE system: Flexpower One: FX3048T, (2) FM80, MATE3s, FlexNetDC
Outback 200NC batteries (8 @ 48v)
Outback IBR3 battery enclosure
Suniva 330 watt panels (12 - 6 Strings @ 2 Series)
Hyundai 355 watt panels (6 - 3 strings @ 2 series)

Re: Normal output in hot days?

Postby SandyP on Sun Jun 09, 2019 4:59 pm

Shadow_Storm56 wrote:....Both arrays combined will do 4300W total and the max I will get on a moderate hot day is 3.6. The max on a peak summer heat would be 3-3.2. Is it normal for it to drop that badly in high heat....


Are you looking at your panel's STC rating or the NOCT rating - usually around a 25% difference?

Nominal Operating Cell Temperature (NOCT) accounts for the heat of the panel and means that solar panels will always have higher ratings at Standard Test Conditions (STC) compared with NOTC
SandyP
Forum Guru
 
Posts: 311
Joined: Tue Jun 21, 2011 4:44 am
Location: Victoria, Australia
My RE system: 8 x 190W 24V Suntech panels (4 strings of 2)
4 x 325W 24V Suntech panels (2 strings of 2) added Sept2018
Mate2
Outback FM60 MPPT (max output lowered to 55amps)
12 x 2V Hoppecke GEL 660 Ah C100 - 24V System
Outback VFX3024 Inverter/Charger
Victron BMV-602s
Honda 5.5kW Genset

Re: Normal output in hot days?

Postby Shadow_Storm56 on Sun Jun 09, 2019 6:17 pm

I'm just going by it's rating, 275w panels. I would assume this is the optimal conditions one
Shadow_Storm56
Forum Guru
 
Posts: 148
Joined: Thu Aug 02, 2018 8:29 pm
My RE system: Solar panels, charge controllers , outback radian inverter.

Re: Normal output in hot days?

Postby raysun on Sun Jun 09, 2019 6:24 pm

Just as an empirical data exercise, have you noted the voltage curve when the temperature rises? The charge controller would be an easy place to monitor that.
raysun
Forum Czar
 
Posts: 623
Joined: Tue Jul 26, 2016 5:57 am
My RE system: Flexpower One: FX3048T, (2) FM80, MATE3s, FlexNetDC
Outback 200NC batteries (8 @ 48v)
Outback IBR3 battery enclosure
Suniva 330 watt panels (12 - 6 Strings @ 2 Series)
Hyundai 355 watt panels (6 - 3 strings @ 2 series)

Re: Normal output in hot days?

Postby SandyP on Sun Jun 09, 2019 7:11 pm

Shadow_Storm56 wrote:I'm just going by it's rating, 275w panels. I would assume this is the optimal conditions one


Edit : Yes it will be the optimal (ie STC), panel "sticker" ratings are STC.
Last edited by SandyP on Sun Jun 09, 2019 8:23 pm, edited 1 time in total.
SandyP
Forum Guru
 
Posts: 311
Joined: Tue Jun 21, 2011 4:44 am
Location: Victoria, Australia
My RE system: 8 x 190W 24V Suntech panels (4 strings of 2)
4 x 325W 24V Suntech panels (2 strings of 2) added Sept2018
Mate2
Outback FM60 MPPT (max output lowered to 55amps)
12 x 2V Hoppecke GEL 660 Ah C100 - 24V System
Outback VFX3024 Inverter/Charger
Victron BMV-602s
Honda 5.5kW Genset

Re: Normal output in hot days?

Postby pss on Sun Jun 09, 2019 8:16 pm

pss
Forum Guru
 
Posts: 232
Joined: Mon Jul 24, 2017 8:40 am
My RE system: 8330 watts in three strings, Flexmax 60 x 3, Radian 8048A, GSLC load center, Mate 3S, Hub 10.3, FN-DC and 900 Amp, 48V Trojan T105-RE battery bank.

Re: Normal output in hot days?

Postby Shadow_Storm56 on Sun Jun 09, 2019 8:31 pm

From that post the guy getting 5000 instead of 7800 sounds like I basically am getting exactly as expected. I find every sunny day I get about the same output, for most seasons because in winter I get so much more but the days are shorter and in summer the days are longer but it is so hot. I have an array that going by the panel rating works out to 4300w, I get about 30-32kw per sunny day from this system. In the cold of winter it could put out almost 5 but my inverter cannot handle that and obviously it would not be sustained anyway. It sounds like all is good though so yay!
Shadow_Storm56
Forum Guru
 
Posts: 148
Joined: Thu Aug 02, 2018 8:29 pm
My RE system: Solar panels, charge controllers , outback radian inverter.

Re: Normal output in hot days?

Postby pss on Mon Jun 10, 2019 5:43 pm

Ambient temp here today was about 112. My system reached the point where in the middle of the day with the batteries 100% SOC, the PV went to ZERO, the charge controllers to silent and all load supplied from grid in broad daylight. This is system stress. I wound up putting a fan on the inverter and charge controllers and dropped the AC input to continue to harvest PV. This type of extreme heat is resulting in a 25% reduction in PV harvest from an optimal April cool day.
pss
Forum Guru
 
Posts: 232
Joined: Mon Jul 24, 2017 8:40 am
My RE system: 8330 watts in three strings, Flexmax 60 x 3, Radian 8048A, GSLC load center, Mate 3S, Hub 10.3, FN-DC and 900 Amp, 48V Trojan T105-RE battery bank.

Re: Normal output in hot days?

Postby Megunticook on Tue Jun 11, 2019 4:23 am

pss wrote:Ambient temp here today was about 112.

Holy heatwave, Batman. That sounds downright dangerous. Where are you located?

This is going to become more and more of an issue as climate change accelerates.

At this point where I am (44 degrees L) we get a few summer stretches in the 90s but nothing too severe. I have noticed a noticeable dropoff in peak power production in the summer, and the most productive days seem to be in spring, when the sun is getting bright, days are lengthening, and temperatures are still cool.

This is only my second summer but here's what the first year looked like in terms of monthly production:

Image
https://sunnypower.org
User avatar
Megunticook
Forum Guru
 
Posts: 179
Joined: Fri Sep 29, 2017 4:08 am
Location: Maine
My RE system: 6.4 kW solar array (21 QCell 305 panels in strings of 3)
GS8048A FLEXpower Radian (Radian 8048A, 2 FlexMax 80 cc's, Mate 3s, FlexNet DC, Hub)
8x6v Rolls-Surette 550 FLA batteries, 428AH

Re: Normal output in hot days?

Postby pss on Tue Jun 11, 2019 8:14 am

So Cal.

One of the most interesting things about solar power is the loss of production with rising panel temperatures. Panel rated wattage is always under ideal conditions. STC and NOCT ratings should be on the label of every reputable panel manufacturer. I would say depending on your geographic location, pay most attention to the NOCT. When making a purchase of panels and an entire system, consider the hottest sunny days at your location and the coldest sunny days at your location and estimate your production below (summertime) and above (wintertime) the NOCT. Then consider if running AC will be necessary. Use this need as your maximum load requirement and how many panels and arrays to build then use the coldest day as your maximum wattage output to size an individual array and charge controller. Next remember that AC will consume a lot of battery power after PV has waned, so don't realistically expect to run your central AC or even 2 tons of AC off batteries without having a very large battery bank. If that is your goal, then I would advise a compromise solution with a generator or fuel cell if staying off grid entirely.
pss
Forum Guru
 
Posts: 232
Joined: Mon Jul 24, 2017 8:40 am
My RE system: 8330 watts in three strings, Flexmax 60 x 3, Radian 8048A, GSLC load center, Mate 3S, Hub 10.3, FN-DC and 900 Amp, 48V Trojan T105-RE battery bank.

Re: Normal output in hot days?

Postby Mike Curran on Tue Jun 11, 2019 9:53 am

I have noticed a noticeable dropoff in peak power production in the summer, and the most productive days seem to be in spring, when the sun is getting bright, days are lengthening, and temperatures are still cool.

I live at about the same latitude as you Megunticook and I also get max output in the months of March, April and May. Combination of cool, sunny days and the fact that the trees are still mostly bare helps. My electric bills for these 3 months are consistently the lowest of the year - last April I got a $0.48 credit to my account!
http://www.tigoenergy.com/site.php?95b2dca2-ca6c
https://enlighten.enphaseenergy.com/public/systems/Hctc107221
Mike Curran
Forum Emperor
 
Posts: 1072
Joined: Sat Aug 28, 2004 6:28 pm
Location: Chagrin Falls, Ohio
My RE system: Outback:
- 8 (2x4) Evergreen 180's into one MX60 (2007)
- 6 (2×3) ALEO S79-300's into one FM80 (2017)
- 2 grid-tied GVFX3524's classic stacked for 120/240VAC (2007)
- 12 Surrette/Rolls 2V x 1766Ah (2007)
- Hub10.3, Mate3s, FNDC, RTS, OpticsRE. Tigo Energy ES maximizers on each PV module.

Westinghouse Solar: (2012)
- 30 (2x15) 235W panels with Enphase M215 microinverters, grid-tied.

All self-designed and self-installed

Re: Normal output in hot days?

Postby JRHill on Wed Jun 12, 2019 11:01 am

Well, it just happens. The days are longer. But the panels are not in the right exposure - actually I lose exposure in the summer, But still don't run a gen until Sept.
JRHill
Forum Czar
 
Posts: 547
Joined: Thu Feb 17, 2011 12:12 pm
Location: South central WA
My RE system: -House: FM 80, VFX 3648, FlexnetDC, FlexWare xformer, Mate 3 / Hub, WattPlot/, 2925w SunTech 195, Trojan L16RE-B Batteries. Backup 1: Honda EU7000is w/2 wire auto start via FM80 aux, backup 2: 11kw Miller Bobcat;
-Well: Grundfos 11-SQF-2 pump, controller & AC switch (CU200, IO101), Tristar 45 Controller, 780w SunTech 195, Trojan golf cart batteries.
-All running since July '11 with various upgrades and workarounds.

Re: Normal output in hot days?

Postby JRHill on Wed Jun 12, 2019 11:04 am

pss wrote:So Cal.
One of the most interesting things about solar power is the loss of production with rising panel temperatures. Panel rated wattage is always


Good post.
JRHill
Forum Czar
 
Posts: 547
Joined: Thu Feb 17, 2011 12:12 pm
Location: South central WA
My RE system: -House: FM 80, VFX 3648, FlexnetDC, FlexWare xformer, Mate 3 / Hub, WattPlot/, 2925w SunTech 195, Trojan L16RE-B Batteries. Backup 1: Honda EU7000is w/2 wire auto start via FM80 aux, backup 2: 11kw Miller Bobcat;
-Well: Grundfos 11-SQF-2 pump, controller & AC switch (CU200, IO101), Tristar 45 Controller, 780w SunTech 195, Trojan golf cart batteries.
-All running since July '11 with various upgrades and workarounds.

Re: Normal output in hot days?

Postby raysun on Wed Jun 12, 2019 2:39 pm

So I guess when the solar radiation is too intense for optimal production, we'll have to install shade cloth like for vegetable beds?
raysun
Forum Czar
 
Posts: 623
Joined: Tue Jul 26, 2016 5:57 am
My RE system: Flexpower One: FX3048T, (2) FM80, MATE3s, FlexNetDC
Outback 200NC batteries (8 @ 48v)
Outback IBR3 battery enclosure
Suniva 330 watt panels (12 - 6 Strings @ 2 Series)
Hyundai 355 watt panels (6 - 3 strings @ 2 series)

Re: Normal output in hot days?

Postby Kurt Lundquist on Wed Jun 12, 2019 2:56 pm

raysun wrote:So I guess when the solar radiation is too intense for optimal production


Heat is the issue. Heat creates resistance which causes voltage drop thus limiting output. This is why cold PV modules can produce more than rated power. Before you get a clever idea I DO NOT recommend hosing off your smoking hot PV modules with cool water.

-Kurt
Kurt Lundquist
Renewable Energy Project Engineer
http://alphaenergy.us/
User avatar
Kurt Lundquist
Alpha Energy Engineering
 
Posts: 1324
Joined: Tue May 31, 2011 7:23 am
Location: Arlington, WA
My RE system: VFX3524, Mate3, 200Ah 24V AGM Battery Bank

Re: Normal output in hot days?

Postby raysun on Wed Jun 12, 2019 2:59 pm

What??? We don't want to experience the thermodynamic properties of modern PV materials in catastrophic temperature change events?

Kurt, where's your sense of adventure?

;)

(Here, we don't use misting with shading. We use tradewinds.)
raysun
Forum Czar
 
Posts: 623
Joined: Tue Jul 26, 2016 5:57 am
My RE system: Flexpower One: FX3048T, (2) FM80, MATE3s, FlexNetDC
Outback 200NC batteries (8 @ 48v)
Outback IBR3 battery enclosure
Suniva 330 watt panels (12 - 6 Strings @ 2 Series)
Hyundai 355 watt panels (6 - 3 strings @ 2 series)

Re: Normal output in hot days?

Postby JRHill on Wed Jun 12, 2019 3:01 pm

raysun wrote:So I guess when the solar radiation is too intense for optimal production, we'll have to install shade cloth like for vegetable beds?


We need GMO veggies that generate power as they grow, that's easiest. I'd try to get the pigs, sheep and goats on a treadmill to generate power but I can't figure out a way to keep excrement from binding up the linkage to the generator. Besides, like me, they complain loudly when they have to do something they don't like.

This off-grid stuff is really hard most days.
JRHill
Forum Czar
 
Posts: 547
Joined: Thu Feb 17, 2011 12:12 pm
Location: South central WA
My RE system: -House: FM 80, VFX 3648, FlexnetDC, FlexWare xformer, Mate 3 / Hub, WattPlot/, 2925w SunTech 195, Trojan L16RE-B Batteries. Backup 1: Honda EU7000is w/2 wire auto start via FM80 aux, backup 2: 11kw Miller Bobcat;
-Well: Grundfos 11-SQF-2 pump, controller & AC switch (CU200, IO101), Tristar 45 Controller, 780w SunTech 195, Trojan golf cart batteries.
-All running since July '11 with various upgrades and workarounds.

Re: Normal output in hot days?

Postby Kurt Lundquist on Wed Jun 12, 2019 3:13 pm

My goats are behind an electric fence so they are a bit of an extra load. You could possibly turn all that poo into something useful. Homepower (RIP) had a cool article on DIY biogas. All their issues are free online to download but I can't remember which one had the article and there isn't a search tool. Google knows of may other examples though. Stink it up!

-Kurt
Kurt Lundquist
Renewable Energy Project Engineer
http://alphaenergy.us/
User avatar
Kurt Lundquist
Alpha Energy Engineering
 
Posts: 1324
Joined: Tue May 31, 2011 7:23 am
Location: Arlington, WA
My RE system: VFX3524, Mate3, 200Ah 24V AGM Battery Bank

Re: Normal output in hot days?

Postby raysun on Wed Jun 12, 2019 3:51 pm

Heh! You goat hearder types!

I'm sticking with PV quanta. Y'all can have that analog gas stuff!
raysun
Forum Czar
 
Posts: 623
Joined: Tue Jul 26, 2016 5:57 am
My RE system: Flexpower One: FX3048T, (2) FM80, MATE3s, FlexNetDC
Outback 200NC batteries (8 @ 48v)
Outback IBR3 battery enclosure
Suniva 330 watt panels (12 - 6 Strings @ 2 Series)
Hyundai 355 watt panels (6 - 3 strings @ 2 series)


Return to Grid Tie Applications

Who is online

Users browsing this forum: No registered users and 4 guests