Adding an extra solar panel .

[Greg & Jax]

Hi all .

Looking for a little advice please .

Currently I have a epever tracer AN 60a  controller with 80a breaker and two 295 panels .

I'm looking to ad another 295 panel and wanted to know if I would need to change the controller to 100a and up the breaker or would these cope with the extra panel . 

Any thoughts would be great .

Regards Greg. 

 

[Jen-in-Wellies]

What are the open circuit voltages of the two 295(W?) panels? Does the proposed new 295(W?) panel have the same open circuit voltage? Are the existing two panels connected in series, or parallel? From this it should be possible to work out if the AN60 Epever solar controller can work with three and if series, or parallel panel connection is best. According to this, the max open solar voltage the controller can take is 180V at 25C. Maximum charging power is 1000W at 12V. Do you have a 12V boat? Three panels at 295W, assuming the 295 is wattage, will be below 1000W, so parallel connection will work. Series connection might work, depending on panel open circuit voltage.

Edited March 28, 2022 by Jen-in-Wellies

[Greg & Jax]

Hi jen .

Thanks for the reply .

Yes we have a 12v boat .

The two panels are in parallel with open circuit voltage of 37.18 each .

The new panel will be exactly the same .

 

[Jen-in-Wellies]

Excellent. Looks like three panels will be fine wired either in series, or parallel in to your current controller.

[Greg & Jax]

Thankyou jen .

I'm quite new to solar so its been a bit of a learning curve. 

Much appreciated. 

[David Mack]

A 60 Amp controller at 12 volts can only put out a maximum of 720 Watts, and you will have an installed power of notionally 885W. But since the panels will never produce their full rated output in the UK, it isn't a problem.

[Alan de Enfield]

4 minutes ago, David Mack said:

But since the panels will never produce their full rated output in the UK, it isn't a problem.

 

I have experienced 100% output in February.

Bright Sun and cold environment and it is achieveable.

[Richard10002]

42 minutes ago, David Mack said:

A 60 Amp controller at 12 volts can only put out a maximum of 720 Watts, and you will have an installed power of notionally 885W. But since the panels will never produce their full rated output in the UK, it isn't a problem.

and even if they do provide full power on some unusual day in February, the controller will merely pass on its max power, and dissipate the extra.

 

So the 60A Tracer will cope fine.

[reg]

It is highly unlikely that you will ever reach 60A and even if you did the Epever Tracer is very good at handling the siutuation in that it has an automatic cut-out mode. The Epever will cut-out at 60A and cut back in when below 60A.

I basically run the same setup but with a 20A Epever, have had no problems.

 

[Greg & Jax]

Thankyou  for the replies guys .

 

[PineappleGuy]

On 29/03/2022 at 19:04, Alan de Enfield said:

 

I have experienced 100% output in February.

Bright Sun and cold environment and it is achieveable.

At what angle were your panels tilted to achieve this?

[Alan de Enfield]

9 minutes ago, PineappleGuy said:

At what angle were your panels tilted to achieve this?

 

Flat-ish on the roof.

I have the triangular mounts that allow you to get a couple of inches of 'slope' but it is not a great deal.

 

Stainless Steel Narrow Boat Solar Panel Flip Standard Mounting Brackets - Low Energy Supermarket

 

 

They are 'special' low light panels originally designed for use in the North of Scandinavia - NOT, low light as in late evening / dusk, but 'low light' as in low angles of incidence as found at higher latitudes, and the UK in Autumn / Winter / Spring

They were sold by Bimble Solar a few years ago. (170 watt and 120 volt)

 

It is the combination of low temperatures and bright sunlight that produce the highest outputs which is why hot Summer days are very bad for panels, and the reason why the stick-down panels fail so quickly. Always mount your panels so you have a free-flow of air beneath them to keep them cooler.

Edited March 31, 2022 by Alan de Enfield

[IanD]

30 minutes ago, Alan de Enfield said:

 

Flat-ish on the roof.

I have the triangular mounts that allow you to get a couple of inches of 'slope' but it is not a great deal.

 

Stainless Steel Narrow Boat Solar Panel Flip Standard Mounting Brackets - Low Energy Supermarket

 

 

They are 'special' low light panels originally designed for use in the North of Scandinavia - NOT, low light as in late evening / dusk, but 'low light' as in low angles of incidence as found at higher latitudes, and the UK in Autumn / Winter / Spring

They were sold by Bimble Solar a few years ago. (170 watt and 120 volt)

 

It is the combination of low temperatures and bright sunlight that produce the highest outputs which is why hot Summer days are very bad for panels, and the reason why the stick-down panels fail so quickly. Always mount your panels so you have a free-flow of air beneath them to keep them cooler.

 

Sorry Alan but the numbers don't back up your assertions.

 

Solar yield is considerably higher in summer than in spring and autumn, see attached plot for optimally angled panels. Solar panel output typically drops by about 1% for 3C increase in temperature, so less than 10% when they get hot in the sun even in midsummer in the UK -- which is a lot less than the dropoff in spring and autumn. Keeping them cool is good but the effect is quite small -- adding airflow underneath is unlikely (and this is being optimistic!) to make them run more than 15C cooler which is 5% extra output.

 

The reason stick-down panels fail quickly is nothing to do with them getting hot, it's to do with manufacturing quality, damage when they bend, and poor quality/fragile connections.

 

There is no such thing as "low light panels that work at low angles of incidence" regardless of what manufacturers claim, output always falls off as sin(theta) due to the laws of optics -- 100% output at 90 degrees, 70% at 45 degrees, 50% at 30 degrees, zero at 0 degrees. No amount of making the surface lumpy can change this, all they do is scatter the light a bit and replace specular reflection with diffuse reflection. You might notice that these "low-light" claims have largely disappeared nowadays since they broke the trade descriptions laws i.e. weren't true.

Edited March 31, 2022 by IanD

[PineappleGuy]

11 minutes ago, Alan de Enfield said:

 

Flat-ish on the roof.

I have the triangular mounts that allow you to get a couple of inches of 'slope' but it is not a great deal.

 

We've been thinking about getting solar but it makes me wonder whether it's actually worth having tiltable panels if they can only tilt a few degrees and the wider the panels the less they will tilt I guess.

[IanD]

5 minutes ago, PineappleGuy said:

We've been thinking about getting solar but it makes me wonder whether it's actually worth having tiltable panels if they can only tilt a few degrees and the wider the panels the less they will tilt I guess.

The maximum gain if you can tilt the panels by 35 degrees *and* they face south (depends on direction the boat points!) is 19% compared to flat mounting, see attached table.

Edited March 31, 2022 by IanD

[Jen-in-Wellies]

2 minutes ago, IanD said:

 

Sorry Alan but the numbers don't back up your assertions.

 

Solar yield is considerably higher in summer than in spring and autumn, see attached plot for optimally angled panels. Solar panel output typically drops by about 1% for 3C increase in temperature, so less than 10% when they get hot in the sun even in midsummer in the UK -- which is a lot less than the dropoff in spring and autumn. Keeping them cool is good but the effect is quite small.

 

The reason stick-down panels fail quickly is nothing to do with them getting hot, it's to do with manufacturing quality and damage when they bend.

 

There is no such thing as "low light panels that work at low angles of incidence" regardless of what manufacturers claim, output always falls off as sin(theta) due to the laws of optics -- 100% output at 90 degrees, 70% at 45 degrees, 50% at 30 degrees, zero at 0 degrees. No amount of making the surface lumpy can change this, all they do is scatter the light a bit and replace specular reflection with diffuse reflection. You might notice that these "low-light" claims have largely disappeared nowadays since they broke the trade descriptions laws i.e. weren't true.

The other big influence on the monthly energy output is going to be the length of the days. Angle of the sun to the horizon will have an effect too, but not as much as the sun being under the horizon for 16 hours a day! 😀

 

[IanD]

2 minutes ago, Jen-in-Wellies said:

The other big influence on the monthly energy output is going to be the length of the days. Angle of the sun to the horizon will have an effect too, but not as much as the sun being under the horizon for 16 hours a day! 😀

 

That's exactly what the picture I posted shows... 😉

[Greg & Jax]

We fitted ours panels  with the normal flat to roof type abs brackets and glued them on rather than drill holes .

Ordered my extra panel from bimble .

 

[GUMPY]

So far in March I have had 430kWh from my house 4.38kW panels facing South at 25deg.

The maximum I have seen 4.731kW at 13.05 on the 18th, mostly it peaks just below 4k.

 

The Panels  on the boat, 480W are laid flat, its better to add  20% extra wattage rather than mess about tilting them.

 

[David Mack]

37 minutes ago, IanD said:

 

That table also shows that if you lay the panels flat, then the performance is the same whatever the orientation of the boat. But if you tilt them then the output drops the further you are from facing south, and you don't have to tilt them very much for the performance of panels facing east or west to be worse than flat panels.

[Alan de Enfield]

14 minutes ago, Loddon said:

The maximum I have seen 4.731kW at 13.05 on the 18th, mostly it peaks just below 4k.

 

No you didn't you cannot get 4.731 Kw from 4.38Kw of panels - IanD has quoted the science to prove it.

The fact I have also had over 100% output (for a short time) makes us both liars.

[GUMPY]

2 hours ago, Alan de Enfield said:

 

No you didn't you cannot get 4.731 Kw from 4.38Kw of panels - IanD has quoted the science to prove it.

The fact I have also had over 100% output (for a short time) makes us both liars.

My monitoring system must be lying to me 

 

 

Edited March 31, 2022 by Loddon
Spill chucker

[PineappleGuy]

1 hour ago, Loddon said:

 

The Panels  on the boat, 480W are laid flat, its better to add  20% extra wattage rather than mess about tilting them.

 

That makes sense to me and would also seem preferable to having a row of brackets interrupting the view along the roof.

[IanD]

3 hours ago, Alan de Enfield said:

 

No you didn't you cannot get 4.731 Kw from 4.38Kw of panels - IanD has quoted the science to prove it.

The fact I have also had over 100% output (for a short time) makes us both liars.

Nope, never said that, please don't put words into my mouth.

 

Panels are rated at a standard incident sunlight intensity, IIRC 1kW/m2 which is representative of noon on a typical sunny day. Nothing says that the sun can't be brighter than this sometimes.

 

The average yield numbers I posted are calculated using actual records of average sunlight over the year -- and they are averages, some days will be better, some will be worse. If you don't like them, suggest you take it up with the various sources who came up with them... 😉

Edited March 31, 2022 by IanD

[Alan de Enfield]

6 minutes ago, IanD said:

The average yield numbers I posted are calculated using actual records of average sunlight over the year -- and they are averages, some days will be better, some will be worse. If you don't like them, suggest you take it up with the various sources who came up with them..

 

 

If you don't like folk saying that they have obtained figures higher than your googling can find why not just accept them.