How about a solar car port on a budget?

[Sophon]

On 7/23/2024 at 9:21 AM, Crossy said:

 

Did you get anything back from Luyuan?

 

Our packs are behaving well and staying well in-balance (we do have the optional active-balancers).

 

 

They claim it's a problem with the JK BMS balancing function and not the cell, and have forwarded data to JK for analysis. So far no further update. Unless you push Luyuan daily they don't follow up on their own, I am not impressed at all with their customer service.

 

Despite the cloudy days we are have had lately our battery stays above 70-75%, so I haven't had the new battery pack shut down because of low voltage protection again. I topped up the "bad" cell when discussing the problem with Luyuan, and on advice from them also flipped the bus bar between cell 9 and 10 and added some contact paste before reattaching it.

[Crossy]

20 minutes ago, Sophon said:

 

They claim it's a problem with the JK BMS balancing function and not the cell, and have forwarded data to JK for analysis. So far no further update. Unless you push Luyuan daily they don't follow up on their own, I am not impressed at all with their customer service.

 

Despite the cloudy days we are have had lately our battery stays above 70-75%, so I haven't had the new battery pack shut down because of low voltage protection again. I topped up the "bad" cell when discussing the problem with Luyuan, and on advice from them also flipped the bus bar between cell 9 and 10 and added some contact paste before reattaching it.

 

We have the Seplos BMS (well known for its chronic balancing system) along with the optional flying-capacitor balancer.

 

It's definitely worth sanding the cell terminals and bus-bars before assembling and the zinc-loaded paste can't hurt.

[Sophon]

2 minutes ago, Crossy said:

 

We have the Seplos BMS (well known for its chronic balancing system) along with the optional flying-capacitor balancer.

 

It's definitely worth sanding the cell terminals and bus-bars before assembling and the zinc-loaded paste can't hurt.

 

My battery pack came fully assembled, so you would expect the seller to put it together in a professional manner.

[Crossy]

Numbers for July.

 

That "big" PEA import (about 160 Baht) was coz the grandkids were visiting and running all the A/C set to "arctic" coupled with some rather dull days running our batteries down.

 

There's still about 6,900 Baht we didn't pay to PEA 🙂 

 

 

[Crossy]

Despite my best will, I'm afraid I was weakened by a 15% Lazada voucher and bought another Deye inverter.

 

[degrub]

Cold spare for the inevitable 😉

[Crossy]

The chickens have been electrified.

 

Currently only 6 x 340W panels since we ran out of mounting hardware, will expand to 9.

 

Large hole in the roof was caused by my step-son standing in the wrong place (hyper-cheap tiles), the smaller hole was caused by my grandson.

 

The roof on the far side of the panels is actually the next-door place.

 

[Pink7]

On 8/8/2024 at 5:10 PM, Crossy said:

Despite my best will, I'm afraid I was weakened by a 15% Lazada voucher and bought another Deye inverter.

 

How do you like your Deye inverters Crossy? You look to have built up some great solar capasity.

 

Pink

[Crossy]

20 minutes ago, Pink7 said:

How do you like your Deye inverters Crossy? You look to have built up some great solar capacity.

 

Pretty happy at present, they have some nice functionality like being able to AC-couple grid-tie inverters on the "Gen" terminals.

 

If you have more than one inverter paralleled each can have its own Gen settings, so one can be AC-coupled whilst another is actually a generator or a Smart-Load (not tried this yet).

 

There are, as always, a few quirks with the initial setup and the online application, but that's what internet forums are for 🙂 

 

LVtopsun do a re-branded version with different firmware for slightly less $$$ but I've not tried these.

 

We currently have 20kWP of panels which makes us waaay over-paneled for our normal weekday load so our batteries are full mid-afternoon even on overcast days. When the grandkids are here at the weekend all bets are off!!

 

[Pink7]

13 minutes ago, Crossy said:

 

There are, as always, a few quirks with the initial setup and the online application, but that's what internet forums are for 🙂

 

I must agree on that..I had some issues with charge not started and sometimes stopped before completed but seems to be solved now after some googling and also got some help.  I also managed see over current protection in BMS log as over Voltage Protection ( who I know did not happened) 

 

Look like Deye is the brand to buy now for who want value for the money.

 

 

Pink

[Crossy]

1 minute ago, Pink7 said:

Look like Deye is the brand to buy now for who want value for the money.

 

They are certainly very popular on the Aussie forums.

[Pink7]

17 minutes ago, Crossy said:

 

They are certainly very popular on the Aussie forums.

I respect everyone to choose to buy what they want and to what price they want. But i must say im happy i not go cheaper than i did and did end up buy something  with lots of  user, so easy to find info online. I see some buy off brand posting for help online with zero reply because no one with knowledge and interest for solar have  same units.

 

In the end in a whole solar setup a few thousand bath +/- on the inverter will not do much on the total. If i should try share any experience to any planing a new setup..Do research and not be cheap on the inverter(s).

 

Regarding your over paneling, means even on cloudy days you probably be ok.

 

Pink

Edited August 20 by Pink7

[Crossy]

Our numbers for August.

Note that with 23kWP of solar we are way over-panelled for our normal daily usage, so production matches consumption fairly closely.

Of course, we have dull days, they always occur when we have family staying and we've actually had to use PEA energy on a couple of occasions to meet their insatiable appetite for A/C.

 

The chicken house / tool shed is now fully loaded with 14 x 340W panels, not ideally located with some shading but they generate useful energy.

 

There really is no more available roof space, well not until I expand the car-port (again) that is

 

 

 

[UWEB]

Why not just cut the big Tree?

[Crossy]

6 minutes ago, UWEB said:

Why not just cut the big Tree?

 

I value my life! 

 

It's not actually a problem coz the house is also in the way early in the day. Those panels only really get going after about 10.30AM.

 

[BritManToo]

Are you combining strings?

If so how,

1. do you match the voltage of the strings then just connect together in parallel?

2. just connect the different voltage strings in parallel?

3. or something different.

 

One of my strings would be in shade early mornings, the other in shade early afternoons.

So although I could match the string panel voltages, the string output voltages would mostly be different. Looked in Google, but they all seem to answer this same question asked many times by changing the original question. Others answering are clearly fools.

 

Edited September 2 by BritManToo

[Crossy]

8 minutes ago, BritManToo said:

Are you combining strings?

If so how,

1. do you match the voltage of the strings then just connect together in parallel?

2. just connect the different voltage strings in parallel?

3. or something different.

 

If you want to parallel strings you need to ensure that the Vmp of each string matches pretty closely or the higher-voltage string will be restricted to the voltage from the lower voltage string.

 

We're not combining strings. We have 8 strings of 9-11 panels in series plus a couple of shorter ones (P1 & T2, these have the worst of the shading).

 

Each string goes to a 500V MPPT input on one of our 4 x 2-input inverters.

 

Note that these are all series strings, the interconnects on the drawing are just to show how the panels are grouped.

 

 

[Muhendis]

39 minutes ago, BritManToo said:

3. or something different.

 

There are things called combiner boxes which allow safe connection of multiple, parallel strings.

These boxes also have lightning protection and fuses for each string. Otherwise it can be regarded as a junction box.

The output goes to the solar input of the inverter.

If you do this using the combiner box there is no need to worry about different outputs from each string as they are effectively isolated from each other.

The output from the combiner box will be a balance of the panels best outputs and none will be dragged down by it's less capable pals.

 

[Crossy]

33 minutes ago, Muhendis said:

There are things called combiner boxes which allow safe connection of multiple, parallel strings.

These boxes also have lightning protection and fuses for each string. Otherwise it can be regarded as a junction box.

The output goes to the solar input of the inverter.

If you do this using the combiner box there is no need to worry about different outputs from each string as they are effectively isolated from each other.

The output from the combiner box will be a balance of the panels best outputs and none will be dragged down by it's less capable pals.

 

This is true provided that your combiner box includes blocking-diodes (not all do), which will prevent the higher voltage string from feeding back into the lower voltage string (which it really won't like).

 

You still need your string voltages to be at least approximately the same for best performance. 

[Muhendis]

1 hour ago, Crossy said:

provided that your combiner box includes blocking-diodes (not all do)

I have never heard of any that don't have blocking diodes. Why would anyone build a combiner box without diodes?

Mine has 25A Schottky bridge rectifiers cunningly connected to accept two inputs each. 

[BritManToo]

2 hours ago, Crossy said:

 

This is true provided that your combiner box includes blocking-diodes (not all do), which will prevent the higher voltage string from feeding back into the lower voltage string (which it really won't like).

 

You still need your string voltages to be at least approximately the same for best performance. 

Thought the solar panels had blocking diodes in them.

The combiner boxes I've seen only had fuses in them.

[Muhendis]

1 hour ago, BritManToo said:

Thought the solar panels had blocking diodes in them.

All solar panels that I know of have diodes in their junction boxes on the back. These are bypass diodes.

They are there so that if a string of three panels has a failure of one cell on e.g. the middle panel, there is a current path through this diode to allow the remaining panels to continue functioning after a fashion. the solar panel itself is little more than a whopping great big diode. This is why, on the face of it, you don't need blocking diodes. But solar panels are not designed to be blocking diodes and so additional protection of diodes in the combiner box is considered to be necessary.

[carlyai]

@Muhendis wrote: '..the solar panel itself is little more than a whopping great big diode.'

Can you explain this a bit more please, with respect to 0.7 V forward bias.

[Crossy]

10 minutes ago, carlyai said:

@Muhendis wrote: '..the solar panel itself is little more than a whopping great big diode.'

Can you explain this a bit more please, with respect to 0.7 V forward bias.

 

Yellow wire (panel +ve) is pin-2, this panel has no bypass diode and is in the dark (ok, face down).

 

 

[Muhendis]

14 minutes ago, carlyai said:

@Muhendis wrote: '..the solar panel itself is little more than a whopping great big diode.'

Can you explain this a bit more please, with respect to 0.7 V forward bias.

Simply put.

A solar cell is made from a reasonably pure silicone sheet. 

Each cell is "doped" in a vacuum during manufacture with different gases which will modify the silicone into 'N' type on one side and 'P' type on the other.

Thus an NP junction is formed similar to a diode. It is this junction which is termed 'P' type that has a forward bias of ≈0.5 to 0.6v. However the solar cell is sensitive to light and it's this sensitivity which gives us the ≈0.5 to 0.6v when light shines on it. This is the open circuit voltage with no current flowing. There are panels on the market now which have a higher junction voltage of ≈0.63v and also a better temp. co. 

 

The silicon diode has a junction which, although made the same way, is slightly different and designed to carry a specific amount of current in one direction. There are many different types of silicon diode the small ones (1Amp 'ish) will have a forward voltage drop of about 0.7v. Larger beasties can be ads much as 1.1v. This is why schottky diodes are better for higher currents because their Vfwd is considerably less than a bog standard 1Amp 1N4007 for example.

 

As an aside, transistor radios used to be made with not silicon but germanium transistors. The OC45 comes to mind. If one were to scrape the paint off 'em they would make excellent light sensors but at a fraction of the price of purpose made devices. After a while the plastic encapsulation was made opaque which put a stop to that cheap trickery. 

[Muhendis]

52 minutes ago, carlyai said:

Can you explain this a bit more please, with respect to 0.7 V forward bias.

For further reading and because I'm way too lazy to write so many words, have a look at this.

https://www.alternative-energy-tutorials.com/photovoltaics/photovoltaic-panel.html

[Crossy]

23 minutes ago, Muhendis said:

As an aside, transistor radios used to be made with not silicon but germanium transistors. The OC45 comes to mind. If one were to scrape the paint off 'em they would make excellent light sensors but at a fraction of the price of purpose made devices. After a while the plastic encapsulation was made opaque which put a stop to that cheap trickery. 

 

Yeah, we used OC71 transistors, scrape of the paint and it became an OCP71. Opaque goop inside replacing the originally used clear goop put a stop to that for us apprentices.

 

As a related aside, our apprentice training school were given several large sacks of "reject" AC128 PNP germanium transistors which went into many of our projects. Get a handful, find ones that actually had two junctions, stick on the curve tracer to check they had at least some gain. Build your audio amp or whatever.