solar panel predicted vs actual generation / efficiency

selsdon101

zeupater wrote: »

thin film panels (the type you're looking at) are usually much less efficient in collecting energy per unit area,

Yes, but the point i'm trying to explore is that less efficient per unit area is ok if it allows you to get double the overall area to install onto. if thin film works 27% better in low light then installing on a north facing side as well as the south might not lead to that much of a power drop, especially in a very cloudy country such as the uk.

Its also worth looking at how the two technologies compare in sunny weather as well - typically panels don't work very efficiently when they're too hot, so on a hot summers day efficiency is actually worse than on a cooler sunny day, but how much worse?

Hybrid systems aren't something i've considered, without real world stats its just guesswork...

selsdon101

zeupater wrote: »

Hi

Here's a direct comparison (PVOutput) between a 2.5kWp Hanergy system facing SW and a standard 4kWp system a few miles from it facing W .... don't look at the relative efficiencies, just energy ...

HTH
Z

Its not too useful to compare just one system with another as theres too many variables - different tilt, shade, wether all the panels are oriented the same way...

Averaging out many different systems would give a better comparison but its hard to do with this website.


in the end i might decide against hanergy because of the company rather than their panel's effectiveness, but it would still be useful to see.

Cardew

selsdon101 wrote: »

This seems to be the general opinion here, but we really need to get stats from people who have installed the panels to see. I doubt a 2.5kW low-light optimised panel will give more yield than a 4kW one, but a 3kW one might give more than a similar priced 2kW one, even if half of it is facing the wrong way. Thats whats relevant to my situation.

What would any stats tell you unless 'Panel A' could be compared with 'Panel B' in installations with identical orientation, roof pitch, latitude, shading etc. Even then to be meaningful you would need several years of data.

zeupater

selsdon101 wrote: »

Yes, but the point i'm trying to explore is that less efficient per unit area is ok if it allows you to get double the overall area to install onto. if thin film works 27% better in low light then installing on a north facing side as well as the south might not lead to that much of a power drop, especially in a very cloudy country such as the uk.

Its also worth looking at how the two technologies compare in sunny weather as well - typically panels don't work very efficiently when they're too hot, so on a hot summers day efficiency is actually worse than on a cooler sunny day, but how much worse?

Hybrid systems aren't something i've considered, without real world stats its just guesswork...

Hi

Real world example provided in example above ... stop overanalysing, compare prices, understand what everyone is saying and make the right decision ... or believe the salesman ...

HTH
Z

zeupater

selsdon101 wrote: »

Its not too useful to compare just one system with another as theres too many variables - different tilt, shade, wether all the panels are oriented the same way...

Averaging out many different systems would give a better comparison but its hard to do with this website.


in the end i might decide against hanergy because of the company rather than their panel's effectiveness, but it would still be useful to see.

Hi

Couldn't find many Hanergy systems within the database, however, you have 2 systems just 24km apart, both single aspect, both complete datasets with the Hanergy system having a theoretical advantage being both closer to southerly and having no declared shading .... if the issue is efficiency in terms of kWh/kWp, the Hanergy system is showing to be marginally more efficient whilst in pure generation it falls well short ...

"you pays your money and you takes your choice" ...

HTH
Z

selsdon101

zeupater wrote: »

Hi

Couldn't find many Hanergy systems within the database, however, you have 2 systems just 24km apart, both single aspect, both complete datasets with the Hanergy system having a theoretical advantage being both closer to southerly and having no declared shading .... if the issue is efficiency in terms of kWh/kWp, the Hanergy system is showing to be marginally more efficient whilst in pure generation it falls well short ...

"you pays your money and you takes your choice" ...

HTH
Z

the hanergy sytem has a tilt of 1 degree, which is pretty far from optimal, while the other is 38 degrees, closer to optimal. so whether the hanergy has the theoretical advantage i'm not sure.

look at the period oct14-august15 (the maximum time period with full months data), the 2.5kW hanergy system has 2070kWh output vs 2729kWh for the 4kW Jetion.

So thats 31% higher actual output for the Jetion which has a 60% higher kW rating. But I doubt you could fit a 4kW standard panel onto the same area of roof as a 2.5kW hanergy panel, the kW per area difference isn't that big. a 3.3kW standard panel would be realistic, and scaling down the 2729kWh accordingly we get 2251kWh, which is isn't much better than the hanergy system. So then it comes down to how much of a difference the tilt/orientation/shade makes.

It is interesting to note that 4 months of the year the 2.5kW thin film system output more electricity than the 4kW standard system.

I may be over analysing but I can't sleep so sue me

tunnel

My experience of Hanergy from the many posts on these forums is that the company are trying to sell you something that will cost between 50 and 100% more than a standard install on the promise that they are "better". Even if they do work better than "normal" panels I'm pretty damn sure they don't work 50-100% better.


How much was the quote for the 1.5kWp system?


If they are quite a bit more expensive then why not look at higher Wp panels like benQ's or something similar, at least if you have only a small roof you could get a larger system on it this way!!

Martyn1981

selsdon101 wrote: »

I may be over analysing but I can't sleep so sue me

I also think you are overanalysing a bit, but that's not a bad thing.

First, why ..... well, it all comes down to roof space. If you are short of roof space, then you can pay extra for high efficiency/hybrid panels to squeeze more Wp onto your roof. If you have loads of space, and no hope of being allowed to exceed the 3.68kW DNO limit, then you might opt to go for cheaper low efficiency/thin film panels, to save a few quid.

What I can't get my head around though, is that the Hanergy systems don't appear to be any cheaper. They seem to cost roughly the same kWp v's kWp. Also, they are being offered to folk like yourself, with limited roof space. So you get a smaller system, that generates less.

You may well find that the thin-film panels generate slightly more, but I seem to recall that they have slightly higher degradation rates too. So if in the end, you don't generate much more size for size, have a smaller system reducing overall generation, and have paid roughly the same (Wp v's Wp) then what's the point.

If you're really keen on thin-film, then consider doing both of your rooves, to try to improve the costs, as a 1.2-1.5kWp system is going to be very expensive (proportionately).

Have a play with PVGIS and explore a 2.5kWp SW + 1.5kWp NE system using 'normal panels'. Installing a 'tiny' system on the basis that it'll generate slightly more efficiently doesn't sound sensible to me. At the end of the day you want as big as system as you can fit, whilst considering overall cost and relative ROI.

Back in my American muscle car days when I learned that torque is more important than bhp, there was a simple saying (or two) - 'there's no substitute for cubes', or 'there's no replacement for displacement'.

Mart.

Martyn1981

selsdon101 wrote: »

But I doubt you could fit a 4kW standard panel onto the same area of roof as a 2.5kW hanergy panel, the kW per area difference isn't that big. a 3.3kW standard panel would be realistic,

You're probably right. The Hanergy panels are about 125Wp/m2, whilst regular panels are around 156Wp/m2. However, if space is limited, then you'd look to over options, in which case we have the 285Wp panels, that are roughly the same price per Wp, giving you 178Wp/m2. That lifts you from 2.5kWp (thin film) to 3.56kWp 'normal' panels.

Also, and it's probably not that big a concern, but the Hanergy panels weigh about the same as regular panels, despite being smaller, and having about half the output. For some properties, this might mean a small amount of reinforcing on the inside of the roof, but now I'm probably the one that's overanalysing.

Mart.

selsdon101

tunnel wrote: »

My experience of Hanergy from the many posts on these forums is that the company are trying to sell you something that will cost between 50 and 100% more than a standard install on the promise that they are "better". Even if they do work better than "normal" panels I'm pretty damn sure they don't work 50-100% better.


How much was the quote for the 1.5kWp system?


If they are quite a bit more expensive then why not look at higher Wp panels like benQ's or something similar, at least if you have only a small roof you could get a larger system on it this way!!

the 1.5kWp quote was £3800, which seemed ok considering i'm in SE London where prices are going to be higher than elsewhere in the UK. Some of the positive comments about hanergy on here seem to be from people who have only posted once and then left, which puts me off slightly

i've just received a quote from a local company called fusion electrical who say they can fit a 2.2kW £3920 system (suntech 275) to a 2.4kW £4330 system (using LG 300W panels), with a Solis mini inverter. Thats a tempting deal, definitely seems better value than hanergy - 47% higher peak power for just £120 more.