Solar panels and battery - any real world reccomendations?

[reef]

Panels pick up far more reflected solar now I think than they once could
My highest morning numbers are hit when its foggy.
Sounds unbelievable, but they are West facing, so no direct sun. When we have fog (not heavy) its reflecting solar radiation all over the place and hence my array picks up more solar than even a sunny day.

I am still considering an east array. The tree situation out front (I class front as East as thats where my front door faces) even though we are side on to the road which is due south).
Some of the trees have been removed, but we ahev been told people paid for it, even though its a shared area. Anyway, the tress block due NE right round to SE solar for me. But only from April - Oct.
I am fairly sure I would probably pick up at 1kw or so from a 5kw array. In winter I would be pretty happy to double my solar gain, since thats when I end up having to buy expensive units.

Would mean I would need to ditch the wall mounted S array I was considering, but that would be half the size so E facing would probably add more annually, just be not effective in the very depths of winter.

This is very true, the newer panels are much improved with reflected solar. In January I never had a day when my NW facing 4.62kW array produced less than 1.0kWh. The bigger SE 4.8kW array had three such days.

PVGIS predicts 1.1kWh/day for January on the NW array, but only two days were at or below this and it averaged 1.7kWh despite no direct sunshine at all.

Now we're in May, the SE array is averaging 16.9kWh/day and the NW array 13.6kWh/day (1st to 5th), so they're pretty effective.

 

[Oh Ed not again.]

Are you sure you gain any benefit from increasing the inverter?

My logic is, as your export capped the times when you have very high generation your going to hit export cap, full batteries and full hot water very quickly anyway.
Then your back to the same position, what can you do with it.
When generation is low, your not going to be limited by the clipping anyway.
Plus inverters are more efficient at high % so in winter etc a larger inverter would in theory reduce your output. (Probably, you would need to take account of spikes in winter, but probably the odd spike you miss now would be more than offset by a slightly higher % generation for much longer periods)

IMO your number one should be looking to increase the potential to use/store more (cost effectively) before trying to generate more thats quite likely to be unused.

These are fair points. As I type the inverter has been pinned at 5kW since 9:30am this morning, I've got the car on charge at 2.7kW and the battery is almost finished charging at 2kW. Once the car is charged, I'll flip the immersion on. Days like today, the excess 2kW would be sent out to export if I was able to take advantage of the 7kW on the roof. Only in this case would a bigger inverter would make sense - whilst I'm able to use what's being generated.

Additional storage would be an answer, and easy to implement as I can just hang another GivEnergy battery off of our existing 9kW job. Only problem is price, but at least they're VAT subsidised at the moment.

Like you say in winter/less sunnier periods I'll be lucky if I'm generating 2kW between 12-2pm after then it drops off massively. I think in this case the additional generation capacity on the west facing roof would help keep the levels up for longer.

WRT exporting, I've just noticed our BMS is reporting a 4.6kWh export. Our DNO was the Fast Track 3.6kWh limited jobber, what gives? (Not that I'm complaining!)

So probably battery -> west facing panels -> inverter would make most sense?

 

[Mercenary Keyboard Warrior]

These are fair points. As I type the inverter has been pinned at 5kW since 9:30am this morning, I've got the car on charge at 2.7kW and the battery is almost finished charging at 2kW. Once the car is charged, I'll flip the immersion on. Days like today, the excess 2kW would be sent out to export if I was able to take advantage of the 7kW on the roof. Only in this case would a bigger inverter would make sense - whilst I'm able to use what's being generated.

Additional storage would be an answer, and easy to implement as I can just hang another GivEnergy battery off of our existing 9kW job. Only problem is price, but at least they're VAT subsidised at the moment.

Like you say in winter/less sunnier periods I'll be lucky if I'm generating 2kW between 12-2pm after then it drops off massively. I think in this case the additional generation capacity on the west facing roof would help keep the levels up for longer.

WRT exporting, I've just noticed our BMS is reporting a 4.6kWh export. Our DNO was the Fast Track 3.6kWh limited jobber, what gives? (Not that I'm complaining!)

So probably battery -> west facing panels -> inverter would make most sense?

What make inverter is it?
Can you access the export controls section?
If your installer installed an inverter capable of exporting above the DNO agreed level they should have limited the export. All inverters sold in the UK have to have this functionality. Its also required to be behind an installer only menu.
Some of us on here however know the Solax installer password. I think most of the inverter manufacturers you can find by googling, as long as your installer has not changed it.

I suspect the installer has forgotten/not bothered to set this up.

I would be careful on more battery being export capped, although you could theorycraft forcing some export earlier in the day if you are carrying energy forwards from the previous day.
Giving you a larger store and meaning you can export more just at different times.

No perfect solution and gambling a little on export rates!

 

[Oh Ed not again.]

What make inverter is it?
Can you access the export controls section?
If your installer installed an inverter capable of exporting above the DNO agreed level they should have limited the export. All inverters sold in the UK have to have this functionality. Its also required to be behind an installer only menu.
Some of us on here however know the Solax installer password. I think most of the inverter manufacturers you can find by googling, as long as your installer has not changed it.

I suspect the installer has forgotten/not bothered to set this up.

I would be careful on more battery being export capped, although you could theorycraft forcing some export earlier in the day if you are carrying energy forwards from the previous day.
Giving you a larger store and meaning you can export more just at different times.

No perfect solution and gambling a little on export rates!

SolarEdge SE5000H I believe. No, all locked down. I can't fondle with it, only use the "mySolarEdge" app to get stats and things and API access into Home Assistant. setApp needs the installer password which I don't have (or haven't bothered to obtain/bruteforce )

I mean I'm not complaining, sure I might if I end up melting a cable in the street but hey...

"Today was a good day" well up until around 2pm when we went into "Old Man Yells at Cloud" territory, but clipping yo...

 

[Oh Ed not again.]

@Mercenary Keyboard Warrior yeaaaaah, export limit control is disabled.

 

[Ron-ski]

@Mercenary Keyboard Warrior yeaaaaah, export limit control is disabled.

You have two choices:

1. Call them back to set it up correctly.
2. Setup an automated system to monitor your voltage and if it gets up to 250v slow down the export, and make hay while the sun shines Although this options assumes you have control of your export, which I expect you don't.

Note, I may well be wrong, but I think if you're pushing out too much power than is being used locally then the line voltage will rise too high. UK electric should range between 216v and 253v (is it sad I know that from memory!).

Although this seems to back up my understanding.

I did find this, but not sure if an end user can do it - but enter a different value other than zero.

 

[Oh Ed not again.]

You have two choices:

1. Call them back to set it up correctly.
2. Setup an automated system to monitor your voltage and if it gets up to 250v slow down the export, and make hay while the sun shines Although this options assumes you have control of your export, which I expect you don't.

Note, I may well be wrong, but I think if you're pushing out too much power than is being used locally then the line voltage will rise too high. UK electric should range between 216v and 253v (is it sad I know that from memory!).

Although this seems to back up my understanding.

I did find this, but not sure if an end user can do it - but enter a different value other than zero.

Thanks chap. I'll have a word with the installer, I have no access to the inverter other than view mode. Unless the local password is default still. Will try that later.

I think I saw some settings related to voltage high and low whilst poking about, they had a millisecond value attached to each. I think that was in the Grid Protection section though.

 

[Ron-ski]

Yes there will likely be a point where the inverter shuts down.

Maximum acceptable grid voltage for the installed inverters.When selecting Vgrid Max. rows 1 to 4: V - maximum voltage [V] ms - trip time, in milliseconds. The trip time indicates the time after which the inverter should disconnectfrom the grid if the grid voltage is out of range.The row “Vgrid Max 5” is a special protection setting that tracks the running mean value of the grid voltagemeasurements. The time (in milliseconds) defines the time window over which the measurements areaveraged. If the averaged value exceeds the voltage threshold, the inverter shall trip in less than 100milliseconds.

https://knowledge-center.solaredge.com/sites/kc/files/viewing_grid_protection_values.pdf

.

 

[Oh Ed not again.]

I think I've settled on another 9kw battery, and then a second string on the west facing roof. Reckon I can get 8 panels comfortably which will help massively for the PM generation and winter months.

Then maybe an inverter upgrade if I still have the itch.

 

[Ron-ski]

@94JDH Are you using micro inverters for all these additional panels dotted around your house?

 

[94JDH]

@94JDH Are you using micro inverters for all these additional panels dotted around your house?

No, just Tigo optimisers, I try and balance the string with same direction where possible though.

 

[Ron-ski]

Even with optimises it's far from ideal to have panels pointing in different directions on the same string. At least the strings will be high voltage so cable losses shouldn't be a problem - you must have some long string lengths.

 

[94JDH]

Even with optimises it's far from ideal to have panels pointing in different directions on the same string. At least the strings will be high voltage so cable losses shouldn't be a problem - you must have some long string lengths.

It's more angle than direction - I have 4 strings split across two inverters:
Inverter 1
West on string 1 (9 @ 10 degrees).
South on string 2 (6 @ 90 degrees).
Inverter 2
East on string 1 (9 @ 10 degrees, 2 @ 20 deg).
South on string 2 (9@ 10 degrees, 4 @ 30 deg).

 

[Ron-ski]

Not too bad then. I was going to say you could have two parallel strings per MPPT input, but I see it's limited to 15 amps, so basically one string.

I've been having fun working out my new configuration, cable voltage drop, physical size of the MPPT, maximum voltage of the MPPT etc but I think I've got it sussed now.

 

[SBo]

I have 4 east and 4 west on the same string with Tigos. Each E/W panel produces about 25% less on a sunny day than my south facing panels, but how much this is due to the split string vs the different orientation (and neighbouring houses E/W) I can’t account for.

The Tigos do massively buck the voltage through the day, I’ll upload a screenshot later.

 

[94JDH]

Not too bad then. I was going to say you could have two parallel strings per MPPT input, but I see it's limited to 15 amps, so basically one string.

I've been having fun working out my new configuration, cable voltage drop, physical size of the MPPT, maximum voltage of the MPPT etc but I think I've got it sussed now.

No, works quite well - all 39 panels have Tigos so I can keep an eye on each panel.
Now, just to finalise those 6 extra panels.....

 

[Ron-ski]

My elderly neighbours just got a quote from a company called Evergen, I'm not sure of the specifics as it was a brief phone call to me and they weren't sure on what they were being advised to fit.

From what I could make out, it is 10 panels, 3.6kW inverter and possibly a 3.1kWh battery, first price £16k when queried they came down to £10k. I told them that was far too expensive.

Just done a quick check on Easy PV and they could actually fit 28 panels on their SE and NW roofs.

Why are companies still pushing bog standard 3.6kW very lacking systems for ridiculous sums of money!

I'm also sure they will get as much export as they want within reason, for the very same reason I was able to (mine won't affect them).

 

[94JDH]

My elderly neighbours just got a quote from a company called Evergen, I'm not sure of the specifics as it was a brief phone call to me and they weren't sure on what they were being advised to fit.

From what I could make out, it is 10 panels, 3.6kW inverter and possibly a 3.1kWh battery, first price £16k when queried they came down to £10k. I told them that was far too expensive.

Just done a quick check on Easy PV and they could actually fit 28 panels on their SE and NW roofs.

Why are companies still pushing bog standard 3.6kW very lacking systems for ridiculous sums of money!

I'm also sure they will get as much export as they want within reason, for the very same reason I was able to (mine won't affect them).

Preying on the elderly and vulnerable seems to be the normal for a number of industries - it shouldn't be allowed to happen anymore and sadly no real punishment for it either.
Fortunately you've stepped in at the right time.

 

[Journey]

Why are companies still pushing bog standard 3.6kW very lacking systems for ridiculous sums of money!

It's called scumbaggery and greed, and people who think making a few quid from people who don't know any better is legal theft IMO.

 

[reef]

It's always a 3.6kW inverter aswell. There's a guy around the corner from us who came for a chat as he was getting nearly 8kW of panels and out of the 5 quotes he got, four quoted with a 3.6kW inverter. A lot of installers just won't do a G99 unless asked it seems. Some won't even do it then!

It's still a bit wild west when it comes to solar at times.