Would someone please check my calculations?

[growly_bear]

Hello All
I'm in the process of researching additional solar panels. I have space for 1x200W and 2x120W which will have different voltages and currents, and am trying to see if the loss calculations are correct for parallel and series connections. I aways try to learn before posting, but would really appreciate your feedback on my calculations.

The panels are the Renogy Shadowflux and the figures used are from their website specs.

I've attached a link to show the formulas used

Has anyone any experience of these panels? This is the only space I have on my 6m Hymer so want to maximise the available solar.

Many thanks for your help!

 

[Dargish]

I'm no expert on these calculations but they seem OK. I do question the cost of the panels though. These small panels are ludicrously priced compared to "normal" residential sized panels. For example I paid £56 each, delivered for two 430w panels. If there is any way you can fit one of these then you'd save a lot of money and with no power loss.

https://www.cityplumbing.co.uk/c/pr...-pv/solar-pv-panels/c/1870007/?sort=price-asc

 

[frwjd]

I think you can use separate mppt's for the different power outputs to gain more power overall

 

[growly_bear]

I'm no expert on these calculations but they seem OK. I do question the cost of the panels though. These small panels are ludicrously priced compared to "normal" residential sized panels. For example I paid £56 each, delivered fit two 430w panels. If there is any way you can for one of these then you'd save a lot of money and with no power loss.

Now £60 but free delivery:

JA Solar 430WP Full Black N-Type Bi-Facial PV Module JAM54D41-430/GB

Full Black 430w n-type bifacial module. As a photovoltaic power generation solution platform, JA Solar Technology Co., Ltd. continues to advance its "One Body, Two Wings" strategy. The "One Body" refers to our main industry chain integrating silicon wafers, cells, and modules, while the "Two...

www.cityplumbing.co.uk

Thanks for checking. Much appreciated.
I don't understand how the max power output using working V and I figures gives more than the rating of the panel though!
My Hymer Exsis is narrower at 2m wide and only 6m long. There are vents for 4 sky lights, an extractor fan, an aerial and 2 cupboard vents! I'd post a pic but the roof needs a clean and I'd be ashamed to post it

 

[growly_bear]

I think you can use separate mppt's for the different power outputs to gain more power overall

Yes you're right. I'm trying to see what the power losses are to help me decide. At 5% I might just use the single one on my dcdcmppt controller. It's rated at 600w and Vmax of 50v

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[Raul]

Your calculations are correct, and you would have two options:
-Parallel with a 30A controller min
-Two controllers 20A for the small panels and one 15A for the larger one.
It will be more cabling on the two controllers, and maybe more dosh, but, marginally better results.

 

[growly_bear]

Your calculations are correct, and you would have two options:
-Parallel with a 30A controller min
-Two controllers 20A for the small panels and one 15A for the larger one.
It will be more cabling on the two controllers, and maybe more dosh, but, marginally better results.

Thank you for taking the trouble to check. I am in the process of looking for panels of a size that fits with similar operating voltages.

It was interested to notice the operating voltages of these Renogy panels as they seem relatively high for their size.

Now I have a working model I'll be able to do some more digging...

 

[Lenny HB]

Still being new to motorhoming....is CCP just another britstops,P4N... But for Europe?

I am planning on taking my first trip to France this year, but currently overloaded with apps like the above, as well as campercontact, search for sites. Looking at the website, I take they are a corporate company just buying up the land the aire was on? Have any of you needed CCP on European travels?

Thanks.

I can't see any link to your calculation just a pdf of the spreadsheet you have posted.

You only show off load voltage the calculations need to be based on under load voltages.
I'll have a look when I'm back home later.

 

[Raul]

A high voltage panel is a good thing and often comes from half cut cells, or shingled panels. The advantage of half cut is more area covered by the full corners, and cell count increases the voltage.
Shingled panels are with overlapped cells, giving no space unused= better efficiency for a given area.
Have a look at Craig solar as well, the panels are high quality

 

[Raul]

I can't see any link to your calculation just a pdf of the spreadsheet you have posted.

You only show off load voltage the calculations need to be based on under load voltages.
I'll have a look when I'm back home later.

I'm pretty sure the operating voltage is the VMP and included in calculation.
The other higher voltage is the VOC.

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[growly_bear]

I'm pretty sure the operating voltage is the VMP and included in calculation.
The other higher voltage is the VOC.

Glad I got that right!

 

[growly_bear]

A high voltage panel is a good thing and often comes from half cut cells, or shingled panels. The advantage of half cut is more area covered by the full corners, and cell count increases the voltage.
Shingled panels are with overlapped cells, giving no space unused= better efficiency for a given area.
Have a look at Craig solar as well, the panels are high quality

I've not come across Craig solar so will do that this afternoon.
I did read about shingled ones. They do a slim version too at 505mm wide which is interesting, but 100W is £130
Are these half cut cells? Is that what N type are?

 

[growly_bear]

I've not come across Craig solar so will do that this afternoon.
I did read about shingled ones. They do a slim version too at 505mm wide which is interesting, but 100W is £130
Are these half cut cells? Is that what N type are?

Renogy 16BB N-Type 175 Watt 12V Solar Panel

Explore Renogy's trusted solar panels, lithium batteries, inverters, and off-grid solutions for home backup, RVs, outdoor activities, and sustainable energy in the UK. Achieve energy independence with premium products and expert guidance.

uk.renogy.com

 

[Raul]

N type are a different cell doping, boron doping =N type; it's meant to be more efficient compared to P type= phosphorous doping.
The N type cells are more expensive too.

The best cells are multilayered with heteronumction HTC. Those are silica and amorphous cell wafer stacked to capture a wider light band. Mayer Burger, Eurener, and a couple more manufacturers do those cells. It was invented by Sanyo, later became Panasonic, but, Panasonic pulled out of Europe. LG do a version as well with the buss bar lattice at the back of the cell, giving bypass option for shade at cell level.

 

[growly_bear]

giving bypass option for shade at cell level

Wow!!

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[growly_bear]

Your calculations are correct, and you would have two options:
-Parallel with a 30A controller min
-Two controllers 20A for the small panels and one 15A for the larger one.
It will be more cabling on the two controllers, and maybe more dosh, but, marginally better results.

I've got a Victron 100/20 wired for a portable set up. Wouldn't this be enough (delete the portable) and fit the above in parallel with 36.5 Voc, 16A short circuit and 14.8A working current?

 

[barryd]

A high voltage panel is a good thing and often comes from half cut cells, or shingled panels. The advantage of half cut is more area covered by the full corners, and cell count increases the voltage.
Shingled panels are with overlapped cells, giving no space unused= better efficiency for a given area.
Have a look at Craig solar as well, the panels are high quality

I just installed a Craig Solar panel as part of a solar upgrade. My pal and solar installer expert thought he was being funny when he put it together. I can now see it on the van roof every time I look out the window.

What I liked about it was that it was the smallest 100w size panel I could find to fit the small space it need to go. All the other 100w panels were larger. Seems good but its early days.

 

[RogerIvy]

The calculations are correct.
Based on the panel specs, my suggestion would be to use two separate controllers for the panels if you want max solar yield. I’d use Victron Smartsolar and create a network.

 

[growly_bear]

The calculations are correct.
Based on the panel specs, my suggestion would be to use two separate controllers for the panels if you want max solar yield. I’d use Victron Smartsolar and create a network.

Thanks Roger. More for me to learn about!

 

[Stevie-b]

What about the weight question? Ive been going back and forth if i should get residential panel's like the ones linked from city plumb or flexible. The flexible are less than half the weight.. also i feel more easy to bond down.

I don't have a huge amount of payload to play with.. but the big cheap panels are tempting

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[gus-lopez]

On my solar sheet here it says series= Voc which is the short circuit voltage which is higher than the operating voltage , which is lower?

Whereas parallel is the actual operating current , Imp, of all the panels.

 

[CAB96]

What about the weight question? Ive been going back and forth if i should get residential panel's like the ones linked from city plumb or flexible. The flexible are less than half the weight.. also i feel more easy to bond down.

I don't have a huge amount of payload to play with.. but the big cheap panels are tempting

Flexible are also more prone to heat damage. Generally likely to be shorter lifespan.

 

[Stevie-b]

Flexible are also more prone to heat damage. Generally likely to be shorter lifespan.

I was reading that the lifespan is about the same on the latest ones.. im up in Scotland so i guess heat is unlikely to be a huge problem for me

 

[growly_bear]

What about the weight question? Ive been going back and forth if i should get residential panel's like the ones linked from city plumb or flexible. The flexible are less than half the weight.. also i feel more easy to bond down.

I don't have a huge amount of payload to play with.. but the big cheap panels are tempting

Being a 6m Exsis, payload isn't a huge consideration for me. I just can't get the domestic ones on the roof!

 

[growly_bear]

On my solar sheet here it says series= Voc which is the short circuit voltage which is higher than the operating voltage , which is lower?

Whereas parallel is the actual operating current , Imp, of all the panels.

I've used the operating currents in my calcs for parallel.

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[Montezuma]

Personally, I wouldn't bother with solar panels of any description.

Despite Mr Milliband's obsession with net zero, and his ambition to cover the green belt with solar panels, he is, simultaneously, funding a massive project, with taxpayer's money, which will block the sunlight, and save the planet.

It sound like it's April 1st all over again, but it isn't.

What could possibly go wrong ?

The project will be funded by the Advanced Research and Invention Agency, known as ARIA. The government has set aside £50 million for the controversial experiment, but in total it has been given £800 million of taxpayers' money to use over the next four years.

Experiments to 'dim the Sun' to be given green light by UK government

Britain is set to approve funding of up to £50 million for experiments to dim sunlight in a bid to limit climate change

www.manchestereveningnews.co.uk

Yeah, I know, I know; it ain't going to happen tomorrow, or even next week, next month, or next year, but with the mad obsession with saving the planet, I suppose it will happen eventually.

Which begs the question, is it just a sneaky way of damping down the market for Chinese solar panels.

 

[growly_bear]

Personally, I wouldn't bother with solar panels of any description.

Despite Mr Milliband's obsession with net zero, and his ambition to cover the green belt with solar panels, he is, simultaneously, funding a massive project, with taxpayer's money, which will block the sunlight, and save the planet.

It sound like it's April 1st all over again, but it isn't.

What could possibly go wrong ?

The project will be funded by the Advanced Research and Invention Agency, known as ARIA. The government has set aside £50 million for the controversial experiment, but in total it has been given £800 million of taxpayers' money to use over the next four years.

Experiments to 'dim the Sun' to be given green light by UK government

Britain is set to approve funding of up to £50 million for experiments to dim sunlight in a bid to limit climate change

www.manchestereveningnews.co.uk

Yeah, I know, I know; it ain't going to happen tomorrow, or even next week, next month, or next year, but with the mad obsession with saving the planet, I suppose it will happen eventually.

Which begs the question, is it just a sneaky way of damping down the market for Chinese solar panels.

The world is going insane...

 

[Raul]

Personally, I wouldn't bother with solar panels of any description.

Despite Mr Milliband's obsession with net zero, and his ambition to cover the green belt with solar panels, he is, simultaneously, funding a massive project, with taxpayer's money, which will block the sunlight, and save the planet.

It sound like it's April 1st all over again, but it isn't.

What could possibly go wrong ?

The project will be funded by the Advanced Research and Invention Agency, known as ARIA. The government has set aside £50 million for the controversial experiment, but in total it has been given £800 million of taxpayers' money to use over the next four years.

Experiments to 'dim the Sun' to be given green light by UK government

Britain is set to approve funding of up to £50 million for experiments to dim sunlight in a bid to limit climate change

www.manchestereveningnews.co.uk

Yeah, I know, I know; it ain't going to happen tomorrow, or even next week, next month, or next year, but with the mad obsession with saving the planet, I suppose it will happen eventually.

Which begs the question, is it just a sneaky way of damping down the market for Chinese solar panels.

That experiment has nothing to do with solar panels, it's about reflectors to divert the sun back.
Solar panels are using the solar, not reflecting it. In fact, solar panels glass is made purposely NOT to reflect any photons.

 

[Montezuma]

Wow !!

Taking life a little seriously aren't we ?

Just out of interest, what use will solar panels be, regardless of what they are manufactured from, if there is no solar, of any description, falling upon them, . . . . . or am I missing something ?

 

[herald_400rl]

Personally, I wouldn't bother with solar panels of any description.

Despite Mr Milliband's obsession with net zero, and his ambition to cover the green belt with solar panels, he is, simultaneously, funding a massive project, with taxpayer's money, which will block the sunlight, and save the planet.

It sound like it's April 1st all over again, but it isn't.

What could possibly go wrong ?

The project will be funded by the Advanced Research and Invention Agency, known as ARIA. The government has set aside £50 million for the controversial experiment, but in total it has been given £800 million of taxpayers' money to use over the next four years.

Experiments to 'dim the Sun' to be given green light by UK government

Britain is set to approve funding of up to £50 million for experiments to dim sunlight in a bid to limit climate change

www.manchestereveningnews.co.uk

Yeah, I know, I know; it ain't going to happen tomorrow, or even next week, next month, or next year, but with the mad obsession with saving the planet, I suppose it will happen eventually.

Which begs the question, is it just a sneaky way of damping down the market for Chinese solar panels.

This is the plot to a film/series "Snowpiercer". They even started HS2 for the train element...

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