Solar PV, Where Do I Start, HELP!!!

pw22

Just to add more questions - if you are limited on space, can they quote you for panels higher than 250w? There seem to be a number of panels on the market at the moment at between 270-285w (at a reasonable cost)

Goldfinger09

pinnks wrote: »

forgot to add, what do optimisers have to do with how you split your array across your available roof space, shading or 4he other issues you mention?

Was just replying and you posted again.....

pinnks

That is a feature of PV systems in general (unless you use micro inverters or the SolarEdge solution) because the panels are connected in series. So, one panel in shade pulls the whole string down - lowest common denominator and all that.


But this has nothing to do with optimisers. All they do is alter the AC voltage once the inverter has done the DC/AC conversion. Unless I am mistaken, you could add an optimiser to your house without PV or any other micro generation kit.


Sounds like the quoted is either trying to blinds you with science or doesn't understand what they are talking about...

Dave_Fowler

Perhaps we are talking cross-purposes here. There are power optimizers which control the mains supply voltage to the house-hold appliances to be at a constant 230V and power optimizers as used by Solar Edge to optimize the output of each panel to produce the most power output possible under shading / split roof conditions.

Dave F

zeupater

pinnks wrote: »

I am no expert on optimisers but some people who are far more knowledgeable than me have said there is no point in them. The reasoning seems to be that for modern switch mode power supplies (laptops, phones, TVs and so on) they make no difference and for resistive loads you just keep the source on for longer if the voltage is reigned in but the optimiser - to get the energy out you need to put it in...

I think this leaves old-style transformer type power supplies where they might help but how many do you have and is it worth the cost.

now I'll sit back and let the experts tell me why I am wrong, or perhaps right in my non-expert way

Hi

Looking at the posts I think you've got the 'wrong end of the stick'. The optimisers in question will be to enhance performance from the solar pv array through minimising string losses when shading or small string multiple orientations are required - they're similar to micro-inverters but standardise/optimise the DC feed to a central inverter instead of converting directly to AC.

The 'optimisation' I believe you have in mind is voltage optimisation or power factor correction in the domestic mains environment. In this situation, whatever the incoming AC voltage or apparent household power factor, a unit (box on the wall) either reduces the voltage to a fixed nominal level or corrects the capacitive effect of electronic devices to a power factor to as close to 1 as possible, with manufacturers/suppliers claiming tremendous cost benefits .... however, unlike commercial supplies where billing is based on kVAh, domestic billing is true kWh, therefore power factor correction becomes irrelevant and simply reducing (through optimising) voltage just means that resistive loads take longer to complete their cycle (kettles etc) or, in the case of lights, simply dim by a percentage which is close to that of the reduction ... In a normal domestic environment, with domestic billing, there's absolutely no return on investment for either power factor correction or voltage reduction(/optimisation) ....

HTH
Z

pinnks

I stand corrected. I was thinking of the voltage optimisation and trying to explain what you describe far more eloquently.


Power optimisers on the roof are of course as you describe too.

I must make sure I look at which end the handle is before I pick up that stick - lol

tunnel

pw22 wrote: »

Just to add more questions - if you are limited on space, can they quote you for panels higher than 250w? There seem to be a number of panels on the market at the moment at between 270-285w (at a reasonable cost)

I'm with pw22 on this one. If you're squeezed for space(which it sounds you are) then maybe tell the installers to quote on a dual aspect(S & E(for arguments sake)) install using something like benQ 285Wp panels. They're now priced down to the point that 14 of them gives a 3.99kWp system and is only marginally higher in price than "standard" 250Wp panels.( I worked it out at £200 more)
At least with these panels you're only using the 2 main rooves, then no need for micro inverters or solaredge or the porch roof...providing you top that tree.


If they try bluffing, by all means give them the link to this stockist http://www.swithenbanks.co.uk/Solar_Photovoltaic_Equipment/1133430/BenQ_285W_Green_Triplex_Mono_Black_Frame_Panel.html

pw22

As Tunnel says if you could get a quote for 285w panels (for example) then it would save you some of the extra scaffolding costs which the company have quoted for and also possibly the need for solaredge (depending on what happens with the tree).

Martyn1981

Goldfinger09 wrote: »

Just asking regarding the optimisers, as the last 'quoter' said if you don't have them and you have a 'issue' with shading and / or have a split system, the power output will reduce to rate of the panel that's underperforming...

Which I think he means....

Out of all the panels putting out 'around' 250watts, and one maybe only putting out 180watts, all the other panels will then 'reduce' their rate to match that panel, thus you losing any export and FI tariff etc....

Or have I, or they got it wrong...?

Hiya. Yep, you've pretty much nailed the theory, here's a youtube video for full explanation on SolarEdge (SE):

SolarEdge Pt1/3

As others have said, if you can get your set up down to 2 aspects with no shading, then I don't think you need to worry about SE kit.

However, SE does do what it says on the tin, so if you do have some issues, and are also considering a 3 aspect array ....

[Note, those porch panels may have the same orientation as another array, but do they suffer differing shade, are they the same pitch. If there is a difference, then they could cause some drag.]

.... then a SE set up may be worth it.

One other point, and it's a long shot, but if you are looking at 3 arrays/locations, then you may want/need to consider differing types of panels, for aesthetics, sizing etc. eg the porch roof may suit smaller (or larger) panels for a better fit. If that's the case, then the SE system allows for this too, since panels no longer need to match and can be a mix of different powers.

Mart.

ed110220

There are now quite a lot of "intermediate" efficiency panels out there that are reasonably priced. It used to be more a case of standard efficiency of about 250W or high efficiency of about 330W. The high efficiency are still quite a lot more expensive, say 81p/W for the BenQ 330 from Swithenbanks or 84p/W for Panasonic. Probably still the way to go if you're very short on space, 12 panels or fewer.

If you have space for 13-15 panels then one of the intermediate panel types could make more sense. Say 13 LG 300W or 305W panels, or 14 of the BenQ 285W etc.

Always surprises me that many installers don't suggest panels that will enable you to get the full 4kW on your roof.

Ed