Advanced PV calculator anyone? Or how to..

[puntloos]

My situation:

 

I have a crown roof design, so flat on top and SSE facing roof side (45 degree angle or so)

So I also have a 45 degree E-facing and 45 degree W facing roof.

 

Have some windows in the roof as well. 

 

- How can I maximise (without going nuts), so not N-facing side etc..) the output

- How many panels can I fit around the windows, or should I reconsider the windows

- flat panels on top, or no panels, or panels on stands at an angle (10 deg maybe?)

 

Would love an advanced calculator that would let me play with these features? Or is there a professional who can help me with this?

[kommando]

Use the SMA design website, it will recommend one of their inverters but that's easy to find alternatives, it will take your choice of panels and the location, orientation and angles to give you the predicted outputs. You can do as many reiterations as you like until you find the best combo.

 

https://www.sunnydesignweb.com/sdweb

[JohnMo]

You could actually have two arrays, one east one west, optimisers and two string inverter.  Would increase your winter yields as it would give a longer solar day.

[SteamyTea]

56 minutes ago, kommando said:

Use the SMA design website,

Not used the SMA estimator/chooser for a decade, but it used to tell you how unbalanced the two strings could be and still work with their inverters.

I always liked SMAs kit as an installer, customers could not fiddle with it.

[kommando]

28 minutes ago, SteamyTea said:

Not used the SMA estimator/chooser for a decade, but it used to tell you how unbalanced the two strings could be and still work with their inverters.

I always liked SMAs kit as an installer, customers could not fiddle with it.

I must be working under an illusion then when changing the settings on mine then. No Grid Guard-code needed for my old Sunny Boys.

[SteamyTea]

3 minutes ago, kommando said:

No Grid Guard-code needed for my old Sunny Boys.

Did the installer disable it then.

Had an electrician not set up the country code on a number of installs.  Took weeks to get a code of SMA.  Now spinning of the wheel would change it.

[kommando]

There is a rolling code that changes with the date on your connecting PC, as long as you know the formula of date to code then you can log on as installer. I have one that still wants to be in Germany with that stupid 10 mins average AC voltage rule but the expected DNO AC voltage on it can still be modified so its not an issue, odd that every other setting but the country can be modified on that one. On the others I can change the country including making them Windy Boys or even turn off anti islanding completely.

[SteamyTea]

22 minutes ago, kommando said:

that every other setting but the country can be modified on that one

Yes it did seem an odd method.

SMA sold inverters that were rebranded, can't remember the name now, they were totally unlocked, and cheaper.

[Adrian Walker]

2 hours ago, puntloos said:

Would love an advanced calculator that would let me play with these features? Or is there a professional who can help me with this?

 

 

I use this one - https://re.jrc.ec.europa.eu/pvg_tools/en/

 

[puntloos]

What's the deal with SMA (and others, then?) where you can't fiddle with things yourself? Not sure I'd want to I suppose but why are they locking you out of your own equipment?

[SteamyTea]

1 minute ago, puntloos said:

where you can't fiddle with things yourself

The voltage is closely controlled. So cuts out if it is over generating in the local grid. The voltage can be tinkered with to make it go higher, so not cut out. Very common fiddle to keep supplying power, and therefore FiT payments.

Trouble is, if too many people do it locally, the voltages goes way over the maximum of 230 +10%, so 253 V. Same can be done to the lower voltage which is -6%, 216 V.

[Dillsue]

21 minutes ago, puntloos said:

What's the deal with SMA (and others, then?) where you can't fiddle with things yourself? Not sure I'd want to I suppose but why are they locking you out of your own equipment?

For this reason

2 hours ago, kommando said:

or even turn off anti islanding completely.

DNOs linesmen might not be too happy with you

[puntloos]

Doing some advanced 3D sculpting I figure i could theoretically fit 38 panels of 400W on my roof, not taking into account many practicalities such as that I'd want to sink the panels into the roof rather than bolt them on top etc. 

https://www.zerohomebills.com/product/tsc-powerxt-400r-pm-400w-solar-panel/

38 panels at 216 ex = 8200 quid, total rating of about 15.2kW (400w panels)

 

Of course that would be achieved if all panels face directly south, and in fact none of the panels face south, rear faces SSE.. not likely, but perhaps I can achieve 12kW? Still pretty hefty. Am I right that that's overkill unless I buy tons of batteries?

 

When is it 'too much'? 

 

 

Edited July 25, 2022 by puntloos

[SteamyTea]

5 hours ago, puntloos said:

When is it 'too much'? 

In the summer.

[JohnMo]

You will generate loads of excess power in the summer, but you load limit that if you want, or export if allowed.  In the winter when production is rubbish, you will still have your base loads covered and plenty of hot water by driving your heat pump.

[Dillsue]

9 hours ago, puntloos said:

Of course that would be achieved if all panels face directly south, and in fact none of the panels face south, rear faces SSE.. not likely, but perhaps I can achieve 12kW? Still pretty hefty. Am I right that that's overkill unless I buy tons of batteries?

 

When is it 'too much'? 

 

Having your panels facing different directions gives a longer spread of generation which could be more useful than a massive peak depending on your motivation for installing PV

 

Whether 15kwp is "too much" depends on your motives and set up. In the summer youll likely have too much for self use but in the winter you could cover much of your usage if you have a battery bank. Batteries come with a big environmental footprint, so a consideration if one of your motives is environmental. A long spread of generation may negate the need for batteries or allow a smaller battery pack.

 

If youre happy for excess to go to the grid, and the grid can handle it, then youll never have too much and a gas power station can throttle back a bit on sunny days. On the flip side, if you want to keep everything yourself youll likely need batteries, PV diverters, an EV etc to grab as much as you can

[puntloos]

1 hour ago, Dillsue said:

Having your panels facing different directions gives a longer spread of generation which could be more useful than a massive peak depending on your motivation for installing PV

 

Whether 15kwp is "too much" depends on your motives and set up. In the summer youll likely have too much for self use but in the winter you could cover much of your usage if you have a battery bank. Batteries come with a big environmental footprint, so a consideration if one of your motives is environmental. A long spread of generation may negate the need for batteries or allow a smaller battery pack.

 

If youre happy for excess to go to the grid, and the grid can handle it, then youll never have too much and a gas power station can throttle back a bit on sunny days. On the flip side, if you want to keep everything yourself youll likely need batteries, PV diverters, an EV etc to grab as much as you can

 

I haven't really done storage math yet but I am expecting that I will at least be able to use my car's battery - which is 62kwh - https://eepower.com/news/nissan-to-leaf-could-power-your-home-with-power-control-system/# - and only leave like 20kwh for my driving trips (unless I am truly planning something meaningful)

 

Surprisingly, tesla powerwall are quite wimpy in comparison 13.5kwh.. 

[Dillsue]

I think the latest Leafs support V2H but I understand its a bit of a niche just now so probably worth doing youre homework as to your V2H options.

 

If youve already got big battery capacity then it changes your options somewhat and 15kwp is unlikely to be "to much"