Free solar panel discussion

grahamc2003

furndire wrote: »

Any shading effects the sunlight reaching the panels, and lowers their performance.
QUOTE]

I don't fully understand the effects of shading, but I've been told that even a little shading can pull the output of the whole array to zero, by unbalancing it.

Because of this, the system proposed to me on my se and sw roofs, with panels on both, would have 2 invertors. The se would be in shade for some of the time the sw was getting sun, and vice versa. With a single invertor apparently, I'd only get output when both were getting the sun, so I was told.

If anyone has further info on the effects of the shading of one panel pulling down the rest for some reason, I'd certainly like to know more details.

Nang

grahamc2003 wrote: »

furndire wrote: »

Any shading effects the sunlight reaching the panels, and lowers their performance.
QUOTE]

I don't fully understand the effects of shading, but I've been told that even a little shading can pull the output of the whole array to zero, by unbalancing it.

Because of this, the system proposed to me on my se and sw roofs, with panels on both, would have 2 invertors. The se would be in shade for some of the time the sw was getting sun, and vice versa. With a single invertor apparently, I'd only get output when both were getting the sun, so I was told.

If anyone has further info on the effects of the shading of one panel pulling down the rest for some reason, I'd certainly like to know more details.

Our inverter has two inputs (one for each string). A string consist of a number of panels wired in series. From what I have observed, it seems that each string is only as good for power gen, as the worst panel in the string.

So for instance in a 20 x panel system with 2 strings of 200w panels, if one panel is heavily shaded and only generating 20 w out of it's max of 200w then they will all be generating 20w in that string. So your 2 kw on that string drops to 200w. The string that isn't effected by the shading (the other input to the inverter) seems unaffected and so still generating the 2 kw its rated at.

I think that if the inverter you used was like ours with 2 inputs you might get away with the fact that one string was shaded whist the other was in the direct sunlight.

Also, I had this chap email me about panels that have their own inverters (micro inverters he called them). I don't think these would suffer in the same way as they wouldn't be wired in a string. I would of course want to check the warranty on the panels is the normal 10 years though as I always considered the inverter to be the weak link in the chain.

The only thing I would say though is I am not too convinced that it is cost effective to have a system that is only capable of generating 1/2 of its peak capacity at any point in time.

Gizmosmum_2

grahamc2003 wrote: »

furndire wrote: »

Any shading effects the sunlight reaching the panels, and lowers their performance.
QUOTE]

I don't fully understand the effects of shading, but I've been told that even a little shading can pull the output of the whole array to zero, by unbalancing it.

Because of this, the system proposed to me on my se and sw roofs, with panels on both, would have 2 invertors. The se would be in shade for some of the time the sw was getting sun, and vice versa. With a single invertor apparently, I'd only get output when both were getting the sun, so I was told.



If anyone has further info on the effects of the shading of one panel pulling down the rest for some reason, I'd certainly like to know more details.

You don't need 2 inverters just 2 strings running into 1 inverter. One string will cover the areas of potential shading meaning that instead of knocking all of the panels off it will just knock off the panels in that string. The strings don't even have to be the same size ie you could have 4 on one string and 8 on another it just makes matching the inverter a bit more difficult but it's a lot cheaper than having 2 inverters.

Nang

furndire wrote: »

Thanks Nang. Looks like Max is well up with his panels. Who would have thought it "come to sunny Oldham"
.

Yes I thought that too, but you need to keep in mind that Max bought more expensive panels than us (reflected in his installation cost). If we are going to get the money back in ten years we need to average £1560 (you) and £1580 (me) a year. He on the other hand needs to average £1722 a year.

So I guess its swings and roundabouts.

In conclusion to the 6 months of data captured so far, I think the sales chap who told me "the published yearly generation estimates were conservative and the system had a good chance of paying for itself in 8 years", was talking from his underpants. At this stage I think more likely to be 11 - 12. But who knows Killamarsh or Scunny could become the sunshine capital of the UK (with the weird weather we have had recently).

But I am still happy enough providing it proves to be reliable, but that still remains to be seen.

zeupater

Gizmosmum wrote: »

grahamc2003 wrote: »

You don't need 2 inverters just 2 strings running into 1 inverter. One string will cover the areas of potential shading meaning that instead of knocking all of the panels off it will just knock off the panels in that string. The strings don't even have to be the same size ie you could have 4 on one string and 8 on another it just makes matching the inverter a bit more difficult but it's a lot cheaper than having 2 inverters.

Hi

They are specifying two inverters in order to provide 2xMPPT ..... a single tracker controlling strings on different orientation roofs will not be efficient ...... something like a SB4000TL has two trackers in one unit and should be cheaper than two separate inverters.

HTH
Z

Gizmosmum_2

zeupater wrote: »

Hi

They are specifying two inverters in order to provide 2xMPPT ..... a single tracker controlling strings on different orientation roofs will not be efficient ...... something like a SB4000TL has two trackers in one unit and should be cheaper than two separate inverters.

HTH
Z

Yea the only thing you have to watch with Sunnyboy is they aren't keen on different string lengths so you need to distribute them evenly. It doesn't even really like odd numbers say a 9 and an 8 string - apparently Diehl cope better with different string lengths.

zeupater

Gizmosmum wrote: »

Yea the only thing you have to watch with Sunnyboy is they aren't keen on different string lengths so you need to distribute them evenly. It doesn't even really like odd numbers say a 9 and an 8 string - apparently Diehl cope better with different string lengths.

Hi

I don't really understand the post above when relating to a SB4000TL ....... The inverter mentioned has two MPP trackers, each of which can have two separate strings, therefore on each tracker you can have differently configured arrays, of different size, facing in different directions, resulting in a better efficiency than any single MPPT system could possibly achieve on a multi-plane/uneven string size installation. Add to this the added efficiency of a transformerless (TL) inverter and you have a far higher specification solution for grahamc2003's installation, that is assuming that it's around a 4kWp total installation over the two arrays (note 2 arrays, not 2 strings).

HTH
Z

Gizmosmum_2

zeupater wrote: »

Hi

I don't really understand the post above when relating to a SB4000TL ....... The inverter mentioned has two MPP trackers, each of which can have two separate strings, therefore on each tracker you can have differently configured arrays, of different size, facing in different directions, resulting in a better efficiency than any single MPPT system could possibly achieve on a multi-plane/uneven string size installation. Add to this the added efficiency of a transformerless (TL) inverter and you have a far higher specification solution for grahamc2003's installation, that is assuming that it's around a 4kWp total installation over the two arrays (note 2 arrays, not 2 strings).

HTH
Z

I could be wrong but when I was installing my system I originally wanted 3 rows of 7 panels with 3 strings but couldn't get the SMA software to provide a good match with 3 rows of 7. At the time I took the easy option and installed the extra panel and went for 2 strings of 11 with the SB400TL, but if I was doing it again I'd look at a Diehl inverter which is a bit more flexible. Whichever you use one inverter is definitely better than 2.

BrummyGit

I've struggled through a lot of this thread, but it's so long I may well have missed some points.

I'm getting frustrated with HomeSun and it seems that I'm not alone. My story in short is:

• I live in the West Midlands
• My roof faces approx 5 degrees off South to the east
• My house measures approx 10m x 10m so I have at least 50 sq metres of south facing roof
• Last year I applied to HomeSun and had the survery carried out (no charge)
• There is one tree that 'could' be a risk of afternoon shade in future as it currently shades my garden, but my local farmer has already offered to cut it down in the spring and this has been explained to the surveyor and HomeSun contact "Ian"

In early December Ian from HomeSun called me to say that my home had passed the survey, but that they needed to charge me £5 a month which would be linked to the Retail Price Index after year 1. I was not happy to hear that and demanded to know why they were changing their offer as a monthly charge was never mentioned previously.


Ian explained that there standard offer didn't anticipate 2 things which meant that they had an additional cost around £500 for installation:

1. My house needed scaffolding for the installation
2. My electricity consumer unit didn't have a spare breaker

I told him I thought that this was a load of rubbish, and indeed even the HomeSun brochures show scaffolding for the installation. Also my consumer unit does have a surplus breaker installed - clearly labelled "Re-Use" so the surveyor didn't spot that.

I told Ian that I was prepared to go forward with the original "free" system, but that the £5 per month charge put me off and asked what he could do. He promised to speak to his manager as he knew there was some flexibility and get back to me in a couple of days.

My last contact with Ian was more than a week before Christmas and I've heard nothing since and can't reach him on his mobile.

I am not aware that there is any real reason why my home won't qualify for the full free installation, and my perception is that HomeSun are just trying it on. The lack of contact since is also very frustrating.

Would anyone from HomeSun care to comment of take a look at my case?

HomeSun_company_representative

BrummyGit wrote: »

I've struggled through a lot of this thread, but it's so long I may well have missed some points.

I'm getting frustrated with HomeSun and it seems that I'm not alone. My story in short is:

• I live in the West Midlands
• My roof faces approx 5 degrees off South to the east
• My house measures approx 10m x 10m so I have at least 50 sq metres of south facing roof
• Last year I applied to HomeSun and had the survery carried out (no charge)
• There is one tree that 'could' be a risk of afternoon shade in future as it currently shades my garden, but my local farmer has already offered to cut it down in the spring and this has been explained to the surveyor and HomeSun contact "Ian"

In early December Ian from HomeSun called me to say that my home had passed the survey, but that they needed to charge me £5 a month which would be linked to the Retail Price Index after year 1. I was not happy to hear that and demanded to know why they were changing their offer as a monthly charge was never mentioned previously.




Ian explained that there standard offer didn't anticipate 2 things which meant that they had an additional cost around £500 for installation:

1. My house needed scaffolding for the installation
2. My electricity consumer unit didn't have a spare breaker

I told him I thought that this was a load of rubbish, and indeed even the HomeSun brochures show scaffolding for the installation. Also my consumer unit does have a surplus breaker installed - clearly labelled "Re-Use" so the surveyor didn't spot that.

I told Ian that I was prepared to go forward with the original "free" system, but that the £5 per month charge put me off and asked what he could do. He promised to speak to his manager as he knew there was some flexibility and get back to me in a couple of days.

My last contact with Ian was more than a week before Christmas and I've heard nothing since and can't reach him on his mobile.

I am not aware that there is any real reason why my home won't qualify for the full free installation, and my perception is that HomeSun are just trying it on. The lack of contact since is also very frustrating.

Would anyone from HomeSun care to comment of take a look at my case?

Dear BrummyGit,

I'm sorry that you have not been satisfied with our service.

Just to reiterate, our whole business is built on installing free and low cost solar systems. We receive the Feed-in Tariff, and homeowners receive free electricity. So, if you have the right roof for solar, it is not in our interests to turn you away - both HomeSun and you would benefit from a positive outcome.

In order for me to expedite this matter can you please email me your full address and contact details (including your MSE user name) to [EMAIL="customerservices@homesun.com"]customerservices@homesun.com[/EMAIL]. Please refer to this post when emailing. This will help me track your email in our inbox.

I look forward to hearing from you in due course.

Krish Patel