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Old 14-06-2024, 10:32   #1
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Solar -- some real world data

We hear a lot about various engineering systems. Sometimes rules of thumb, sometimes opinions, but facts are sometimes scarce. I've just done a solar upgrade and want to share the results.

We have just finished a 2-week cruise on the Chesapeake in June. A few days we motored more than we'd like, but these last two days we have a total of less than an hour on the engine. So some real world results.

First, our ship systems. We have a fridge and a freezer on separate compressors. Our freezer is having some minor problems, so has been running 24/7. We have a 3kW inverter that we are not afraid to use, but turn it off when we are not using it. It does include coffee brewed in a Mr. Coffee every morning, toast most mornings, the occasional microwave, and the admiral fries her hair every other day. Our lights are LED, and we occasionally run some hella 12 volt fans. Most instrument loads are low, but our chart plotter draws 5 amps- we only run it when underway. Our batteries are 800 ah of AGM, so reaching absorption is rarely possible.

Coupled with a complete Arch replacement (see other threads regarding the accident and insurance), we upgraded to two 400W solar panels. These are bifacial panels made by JJN obtained off Amazon for about $700 for the pair. Despite strong advice from Jedi, I wired them in parallel. I wrestled with controller size, and decided not to risk 30A and went with two 50A controllers. Existing wiring was 10 gauge, more than ample.

So results?

First, quite surprising, I have yet to break 30A on any controller. In fact, my old 15A controllers would have met my needs over 90% of the time. No regrets on the 50, but they're not providing a lot of value.

My AGM are resetting the Link 2000 battery monitor everyday. This is a huge improvement over my prior life, where getting to 100% was a constant concern.

Most nights, I am still at 100% charge around 6:00 p.m..

I wake up each morning down 100 Ah, and slam another 30 on to it with morning chores.

I am typically seeing over 20A of charge by 8:00 in the morning, and don't drop below 20 before 6:00 p.m.. according to the controllers, daily harvest has been over 800 Wh per day, with a peak of 2kWh. Pmax has often been over 380 w on any given day. I suspect the daily harvest has been limited not by available power, but by required power. I am quite surprised to see a daily harvest at four times panel capacity!

I should mention that I spent a lot of design time. Minimizing shading. Antennas have been pushed low, radar is moving to the mast, the wind generator has been dispensed with.

Much of this is stuff you've seen before, but just wanted to share some experiences with others who might be doing design.
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Old 14-06-2024, 10:53   #2
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Re: Solar -- some real world data

That's good data! As another data point, we have 2x 410W monofacial panels each with its own 30A charge controller (which we've almost maxed out at times). In mid-summer and good weather our typical daily harvest is between 3 and 3.2 kwh, often limited by demand. The highest I've seen in a day was 3.7 kwh. Unless there's something near the boat to provide shading or the sun is low in the sky behind us, we get zero shading in most conditions. In poor weather especially early and late in the season I've seen days where we don't even manage 1 kwh.

I'm not understanding why you have 2 panels wired in parallel and are using 2 controllers. Normally you'd either have the panels in parallel connected to a single controller or the 2 panels each wired separately to its own controller.
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Old 14-06-2024, 11:00   #3
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Re: Solar -- some real world data

Quote:
decided not to risk 30A
For anyone else weighing such choices there is no risk. If you exceed the input VOLTAGE limit on a controller that is a problem. If your panels produce more power than the output CURRENT limit it simply caps your output.

Still not sure why you expected >30A. The panels are 400W max under ideal theoretical conditions. If charging at 14V then 30A is 420W which is more than your panel peak output. Maybe something got lost in translation. If you had wired the panels together (series or parallel) and were using only one controller then you would need 50A.

Lastly how do you have the panels wired in parallel if you have 2 panels and 2 controllers?
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Old 14-06-2024, 11:01   #4
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Re: Solar -- some real world data

Quote:
Originally Posted by rslifkin View Post
That's good data! As another data point, we have 2x 410W monofacial panels each with its own 30A charge controller (which we've almost maxed out at times). In mid-summer and good weather our typical daily harvest is between 3 and 3.2 kwh, often limited by demand. The highest I've seen in a day was 3.7 kwh. Unless there's something near the boat to provide shading or the sun is low in the sky behind us, we get zero shading in most conditions. In poor weather especially early and late in the season I've seen days where we don't even manage 1 kwh.

I'm not understanding why you have 2 panels wired in parallel and are using 2 controllers. Normally you'd either have the panels in parallel connected to a single controller or the 2 panels each wired separately to its own controller.

Sorry, I wasn't clear. They are not wired in parallel, they function in parallel. Each solar panel is connected to its own dedicated controller. So maybe parallel doesn't belong in the discussion at all!
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Old 14-06-2024, 11:03   #5
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Re: Solar -- some real world data

Quote:
Originally Posted by sailingharry View Post
Sorry, I wasn't clear. They are not wired in parallel, they function in parallel. Each solar panel is connected to its own dedicated controller. So maybe parallel doesn't belong in the discussion at all!
That makes more sense. Other than cost that is the ideal scenario.
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Old 14-06-2024, 11:05   #6
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Re: Solar -- some real world data

Quote:
Originally Posted by sailingharry View Post
Sorry, I wasn't clear. They are not wired in parallel, they function in parallel. Each solar panel is connected to its own dedicated controller. So maybe parallel doesn't belong in the discussion at all!
Gotcha! Same way mine are configured then. 1 controller per panel is pretty much the ideal way to do it if the panels have a high enough open circuit voltage. Especially if they're angled slightly differently like mine are (they're arched to follow the deck camber).
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Old 15-06-2024, 03:55   #7
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Re: Solar -- some real world data

My set up is pretty modest in comparison but the main thing I did differently is to wire my 2 - 100w panels in series. They are run through a Victron MPPT 75/15 controller with a Bluetooth app.

What really gives me a kick is when I see the input voltage up in the high 30's and the current just a few amps but the output at 13-14v and the current maxed out at around 11 amps. And it will do this even on cloudy days or when the sun is not at a good angle or even when partially shaded.

I'm essentially getting all the power my panels can produce.

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Old 15-06-2024, 07:33   #8
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Re: Solar -- some real world data

Quote:
Originally Posted by OldManMirage View Post
My set up is pretty modest in comparison but the main thing I did differently is to wire my 2 - 100w panels in series. They are run through a Victron MPPT 75/15 controller with a Bluetooth app.

What really gives me a kick is when I see the input voltage up in the high 30's and the current just a few amps but the output at 13-14v and the current maxed out at around 11 amps. And it will do this even on cloudy days or when the sun is not at a good angle or even when partially shaded.

I'm essentially getting all the power my panels can produce.

With smaller, lower voltage panels, that's the right way to do it in my mind.

My big panels are much higher voltage. Rated Vmpp is 41.7, Voc is 51.2. Those numbers come down a bit in hot weather when the panels heat up, of course. Right now the boat is on shore power with full batteries, so the panels are just keeping up with some DC loads. One panel is doing nothing and showing 46.4V, the other is putting out 84W and showing 45.4V. Current conditions are 10:32 AM, crystal clear blue skies with full sun. Boat is facing NE, which is sub-optimal for solar output (facing S is better) as the panels are angled slightly forward on the boat and slightly outboard to the sides.
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Old 15-06-2024, 09:29   #9
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Re: Solar -- some real world data

Quote:
Originally Posted by sailingharry View Post

I am typically seeing over 20A of charge by 8:00 in the morning, and don't drop below 20 before 6:00 p.m.. according to the controllers, daily harvest has been over 800 Wh per day, with a peak of 2kWh. Pmax has often been over 380 w on any given day. I suspect the daily harvest has been limited not by available power, but by required power. I am quite surprised to see a daily harvest at four times panel capacity!

.
Is that 20A per panel/controller, or 20A total?
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Old 15-06-2024, 10:06   #10
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Re: Solar -- some real world data

Quote:
Originally Posted by sailingharry View Post
We hear a lot about various engineering systems. Sometimes rules of thumb, sometimes opinions, but facts are sometimes scarce. I've just done a solar upgrade and want to share the results.

We have just finished a 2-week cruise on the Chesapeake in June. A few days we motored more than we'd like, but these last two days we have a total of less than an hour on the engine. So some real world results.

First, our ship systems. We have a fridge and a freezer on separate compressors. Our freezer is having some minor problems, so has been running 24/7. We have a 3kW inverter that we are not afraid to use, but turn it off when we are not using it. It does include coffee brewed in a Mr. Coffee every morning, toast most mornings, the occasional microwave, and the admiral fries her hair every other day. Our lights are LED, and we occasionally run some hella 12 volt fans. Most instrument loads are low, but our chart plotter draws 5 amps- we only run it when underway. Our batteries are 800 ah of AGM, so reaching absorption is rarely possible.

Coupled with a complete Arch replacement (see other threads regarding the accident and insurance), we upgraded to two 400W solar panels. These are bifacial panels made by JJN obtained off Amazon for about $700 for the pair. Despite strong advice from Jedi, I wired them in parallel. I wrestled with controller size, and decided not to risk 30A and went with two 50A controllers. Existing wiring was 10 gauge, more than ample.

So results?

First, quite surprising, I have yet to break 30A on any controller. In fact, my old 15A controllers would have met my needs over 90% of the time. No regrets on the 50, but they're not providing a lot of value.

My AGM are resetting the Link 2000 battery monitor everyday. This is a huge improvement over my prior life, where getting to 100% was a constant concern.

Most nights, I am still at 100% charge around 6:00 p.m..

I wake up each morning down 100 Ah, and slam another 30 on to it with morning chores.

I am typically seeing over 20A of charge by 8:00 in the morning, and don't drop below 20 before 6:00 p.m.. according to the controllers, daily harvest has been over 800 Wh per day, with a peak of 2kWh. Pmax has often been over 380 w on any given day. I suspect the daily harvest has been limited not by available power, but by required power. I am quite surprised to see a daily harvest at four times panel capacity!

I should mention that I spent a lot of design time. Minimizing shading. Antennas have been pushed low, radar is moving to the mast, the wind generator has been dispensed with.

Much of this is stuff you've seen before, but just wanted to share some experiences with others who might be doing design.
What solar controllers are you using. Are you reading amps before or after the MPPT?
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Old 16-06-2024, 10:16   #11
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Re: Solar -- some real world data

Quote:
Originally Posted by sailingharry View Post
I am typically seeing over 20A of charge by 8:00 in the morning, and don't drop below 20 before 6:00 p.m.. according to the controllers, daily harvest has been over 800 Wh per day, with a peak of 2kWh. Pmax has often been over 380 w on any given day. I suspect the daily harvest has been limited not by available power, but by required power. I am quite surprised to see a daily harvest at four times panel capacity!
This is in line with what we see off our 400 watts, We’re further north, but in the summer months we generally see about 700 Wh/day, but can tip over the 1000 Wh mark.

My system consists of four panels, all run in parallel through a single controller (victron 100/30).
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Old 16-06-2024, 10:55   #12
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Re: Solar -- some real world data

we have 3x 410wp simple ones on one victron 150/70.

here in portugal often hitting the max 70 amps.

record in last weeks is 8.4 kwh in 24 hrs
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Old 17-06-2024, 05:47   #13
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Re: Solar -- some real world data

Quote:
Originally Posted by Mike OReilly View Post
This is in line with what we see off our 400 watts, We’re further north, but in the summer months we generally see about 700 Wh/day, but can tip over the 1000 Wh mark.

My system consists of four panels, all run in parallel through a single controller (victron 100/30).
With 30A output in the 100/30 controller aren’t you trimming your output? Our SunPower Maxeon 395W panels often produce well above 15A at 13.8V out of their controller. What is your output voltage and current?

At 30* south of the sun in June we see 1.5-1.8kWh per 395W panel and up to 6A each at 65V.
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Old 17-06-2024, 06:04   #14
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Re: Solar -- some real world data

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Originally Posted by fxykty View Post
With 30A output in the 100/30 controller aren’t you trimming your output? Our SunPower Maxeon 395W panels often produce well above 15A at 13.8V out of their controller. What is your output voltage and current?

At 30* south of the sun in June we see 1.5-1.8kWh per 395W panel and up to 6A each at 65V.
I'm not sure if I'm limiting things. We regularly see upwards of 18-20 amps coming out of the controller. Very occasionally it has exceeded 25 amps. With 400 watts. Voltage outputs at the panels hover in the 21v range -- my panels are rated ~22v. Output voltage varies with stage of charging: 14.4 to 12.8 (I think... I'd have to check. Lead acid batteries).

With 400 watts I have a theoretical max of 33 amps, which of course would exceed the controller capacity. I don't know if the MPPT ever throttles the output, but I really doubt it. I rarely see more than 320 watts coming off the panels.

I am at the max for this controller. I probably should have got the 100/50 version, and if I ever want to add more panels I'd have to go up, but for what I have now, the 100/30 seems fine.


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Old 17-06-2024, 06:20   #15
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Re: Solar -- some real world data

year 2012-2022 i have germany made 2x 100w solar panel and victron 70/15 mppt not smart my winston cell 400ah 12v be full charged around 12-14.00 depend .by victron average day harvest 1000-1250 wh lot time i see 15a charging ussualy sun and wind condition
but last year buy some brand but made in china 2 x150 w 21v soc series and change to 30a mppt i never see 12A charging yesterday first time i see 15A(i put in conector eletrical greas in conector) charging. first in real world mistake i change mppt from 15A to 30A second evry day i need engine +- 1 hour to work. my frige is end of life becouse now working without stop and cooling is week. i try everthing charging gas,changing gas.
but i must change solar panel for premium 445W but dimension 170x 110 cm and must be high voltage more volt beter over 100 v be perfect.

soon new hanse 505 must have 3 or 4 445-450W maybe Trina Solar Vertex S+ i must order 10 pices for 74-78 € pices rest go to reserve.

amazing how old 200W solar panel harvest more energy from fake biger also in size 150W solar panel.
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