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Solar PV Hints, Tips & Troubleshooting

DrPhilG

Well I've reached the point of driving everyone nuts on the PV quotes thread, and since I now have my system installed and running my endless questions no longer belong there.

So I figured I'd ask here, and also provide a home for others in the same boat, with general questions and advice on managing post-install.

My first question (of many) is how do people best manage their production in order to reduce grid export? Despite being overcast and miserable a fair bit of the day, I've produced 24kWh so far today, but ended up exporting 11.

Not too bad when we're home, as the wife did a few loads of washing and drying, put on the dishwasher etc.

But we're both at work tomorrow so other than a timed or remotely activated washer/dryer run we would end up exporting a lot more.

Extra battery capacity or a water diverter would help, but they don't tend to justify their costs in the long term.

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mp3guy

jkforde wrote: »

Apologies for my ignorance and if this has been covered many times elsewhere but boards search functionality is cat. \
I've a new 6.7kW solar up and running (future BEV proofing) and still have the rotating disk 24hr meter.... since I am not consuming the majority at the moment (diverter, battery & BEV imminent ), is the surplus being dumped into the grid? (have observed the disc stops rotating)

I believe this is the golden goose, have you seen it go backwards?

jkforde

mp3guy wrote: »

I believe this is the golden goose, have you seen it go backwards?

thanks for the quick reply.
no, it stays static - the 'red' numbers quiver slightly, like they can't make up their mind!

irishchris

Looking to add hybrid inverter with battery over the coming weeks. Just wondering about the meter with clamp for the hybrid. Is this powered and if so where it its power wired from?

A later project is to relocate the inverter and battery to a shed which would be about 15-20 meters away from house. What size swa AC cable would people here recommend for that run?

MAULBROOK

irishchris wrote: »

Looking to add hybrid inverter with battery over the coming weeks. Just wondering about the meter with clamp for the hybrid. Is this powered and if so where it its power wired from?

A later project is to relocate the inverter and battery to a shed which would be about 15-20 meters away from house. What size swa AC cable would people here recommend for that run?

6sq should be ok

championc

irishchris wrote: »

Looking to add hybrid inverter with battery over the coming weeks. Just wondering about the meter with clamp for the hybrid. Is this powered and if so where it its power wired from?

A later project is to relocate the inverter and battery to a shed which would be about 15-20 meters away from house. What size swa AC cable would people here recommend for that run?

My sparks mate suggested I run 10sq armoured

The clamp gains it's power from inverter that it's connected to I think. So if the run is long, it's important not to use cheap alarm or phone cable

KCross

jkforde wrote: »

no, it stays static - the 'red' numbers quiver slightly, like they can't make up their mind!

If it ain’t going backward you are dumping to the grid for free.

jkforde

KCross wrote: »

If it ain’t going backward you are dumping to the grid for free.

cheers, that's what I suspected. I don't mind in the short term but going to hound ESBN for a smart meter, a campaign of persistence a la Andy's books campaign in Shawshank Redemption! 😂

KCross

jkforde wrote: »

cheers, that's what I suspected. I don't mind in the short term but going to hound ESBN for a smart meter, a campaign of persistence a la Andy's books campaign in Shawshank Redemption! ðŸ˜‚

You won’t get paid for it until FiT comes in (Jul 2021+) regardless of your meter.

You will then have to pick a provider, you don’t just “get paid”.

A provider can, for instance, give you 5c/kWh for your export but give you a crap day rate so effectively taking the money back off you. So you’ll have to weigh it all up at the time.

DrPhilG

So for those currently under contract, we'll have to see it out before we get paid for anything anyway? Energia and their famed 4.7c night rate for example, doesn't include a fit so anyone signing up to it now won't see a cent for Amy export until this time next year.

Or will providers be likely to offer any kind of fit to existing customers?

graememk

DrPhilG wrote: »

So for those currently under contract, we'll have to see it out before we get paid for anything anyway? Energia and their famed 4.7c night rate for example, doesn't include a fit so anyone signing up to it now won't see a cent for Amy export until this time next year.

Or will providers be likely to offer any kind of fit to existing customers?

Won't know until we see the tariffs, also will need to examine if it's actually cheaper to go onto a smart tariff with fit opposed to the standard day/night tariff.

Would you give up the low 4.7c night rate for a fit and a night rate of 10.5c?
Daytime use is covered mainly by solar/maybe overnight charging.

Haven't done the math on this, so this is just theorising
If the fit is say 5c, the amount you would need to export needs to match your night rate use to break even.. .. well that's me out..

slave1

Those last posts have FIT bang on, just have to wait and see and for those of us heavy night rate users e.g. EV it may very well be worthless.
I just hope the price plans are straightforward and not like health insurance plans

SD_DRACULA

KCross wrote: »

If it ain’t going backward you are dumping to the grid for free.

I was wondering about this, if you are maximizing your usage during the day, charging EV or battery and then still some left and going into the grid, can't we just set up a mining raspberry pi cluster that can use all the excess power?

MAULBROOK

SD_DRACULA wrote: »

I was wondering about this, if you are maximizing your usage during the day, charging EV or battery and then still some left and going into the grid, can't we just set up a mining raspberry pi cluster that can use all the excess power?

Are you over thinking things again:D

mp3guy

SD_DRACULA wrote: »

I was wondering about this, if you are maximizing your usage during the day, charging EV or battery and then still some left and going into the grid, can't we just set up a mining raspberry pi cluster that can use all the excess power?

I literally do this. Mining on full blown day rate is very profitable right now, so doing it on excess is not only the most profitable, but also carbon neutral.

SD_DRACULA

MAULBROOK wrote: »

Are you over thinking things again:D

I want to give nothing back to the grid for free, since the grid isn't giving me anything for free

MAULBROOK

20 panels washed and cleaned, the things ya do out of boredom. Also helps living in a bungalow.
When you get up close they do look bad. Will it help, who the hell knows.

jkforde

MAULBROOK wrote: »

20 panels washed and cleaned, the things ya do out of boredom. Also helps living in a bungalow.
When you get up close they do look bad. Will it help, who the hell knows.

was thinking about regular cleaning of bird poo, algae etc, will it be even necessary with wind, rain, UV?!

Deagol

jkforde wrote: »

was thinking about regular cleaning of bird poo, algae etc, will it be even necessary with wind, rain, UV?!

Dunno, I found that a 20mm layer of snow barely changed the amount my panels where producing there a few weeks ago!

ParkRunner

Just out of interest have people with solar PV systems without a battery seen a significant drop in electricity bills? I got my first bill in which is a slight drop on the previous one but am not sure how much of that is seasonal. I only have the panels in place about 3 weeks so it’s still too early to assess this for me so am curious how other peoples bills have been impacted

mp3guy

ParkRunner wrote: »

Just out of interest have people with solar PV systems without a battery seen a significant drop in electricity bills? I got my first bill in which is a slight drop on the previous one but am not sure how much of that is seasonal. I only have the panels in place about 3 weeks so it’s still too early to assess this for me so am curious how other peoples bills have been impacted

All depends on your usage patterns. If like me you use most of the energy in the evening after the sun is gone down, without a battery your bills won't change. Of course a battery has a cost which you have to take into account.

Sure FIT is coming, but it's likely to be fairly poor (~5c/kWh) so you'll make pennies from it most days.

SD_DRACULA

I'm still fighting myself whether to get the battery or not but I am afraid that without it, a 6kw system would probably go mostly to the grid and as you said FIT won't make any real difference.

Coltrane

ParkRunner wrote: »

Just out of interest have people with solar PV systems without a battery seen a significant drop in electricity bills? I got my first bill in which is a slight drop on the previous one but am not sure how much of that is seasonal. I only have the panels in place about 3 weeks so it’s still too early to assess this for me so am curious how other peoples bills have been impacted

Yes in my case. In my original setup which was a 5.2kWp array without battery, I managed about 70% self-consumption over 3 years without too much manual intervention.

My EV and heat pump are good consumers of sunbeams.

Even if you don't have either, you can still change habits eg run the dishwasher and washing machine, heat your hot water, around noon, turn on your oven further ahead of dinnertime and slowcook, to increase your usage.

I would say that export is no waste! You're contributing relatively clean energy to the grid. If you help cut emissions in even that small way that has a value to us all, probably much greater than 5c/kWh!

The cryptominers on here have taken it to the next level, heating their homes and turning a profit (at least while crypto is as valuable as it is!) from their PV!

For me, the main point is to reduce emissions and from that perspective I'm happy to export for free.

slave1

SD_DRACULA wrote: »

I'm still fighting myself whether to get the battery or not but I am afraid that without it, a 6kw system would probably go mostly to the grid and as you said FIT won't make any real difference.

If you're talking about a battery setup to cover a few hours of darkness then it will never pay back.
Not only is there a battery cost but also the inverter is twice as expensive.
We all know they will need to be replaced eventually.
I'd much rather know I've a ~€700 inverter to be replaced versus a ~€2.5k hybrid inverter/single battery.
Maths just don't stack.

KCross

SD_DRACULA wrote: »

I'm still fighting myself whether to get the battery or not but I am afraid that without it, a 6kw system would probably go mostly to the grid and as you said FIT won't make any real difference.

I think you are looking at it the wrong way.

Yes, FiT wont make you rich, but it costs you nothing to install.... its effectively there for free and its money coming in.

On the flip side if you decide you want to consume it all and you put in a battery to stop export happening you are having to spend money up front that may never pay for itself. It might make you feel happy that you are not exporting but you paid for that!

Whats better...
no capital cost and money coming in day 1
or
Up front capital costs that may or may not pay for itself over a 10-15yr period

And the typical battery systems you see quoted for on this forum are tiny in nature 2.4-5kWh.... a 6kWp system will fill those up several times a day anyway so you will still be exporting!... just let it go to the grid and take the FiT!

SD_DRACULA

If no grant then wouldn't bother for sure.
Also wondering how well the battery will perform in the cold months, it is in the attic after all and most (if not all) love temps around 20c and when it goes to 10 or less?

garo

Yes the grant makes the economics slightly less favourable. I'd say close to break even. I estimated that I saved about 150 euro with my 2.4kWh Pylontech last year. YMMV. With the additional grant that 2500 becomes 1300 and your payback comes down to 8-9 years.

Re winter temps, when cold the battery charges more slowly though the discharge rate remains the same. If under 0 - which shouldn't happen in an attic - the battery should stop working altogether. Under 10C my battery only charges at 10A instead of 25A which means March and April I export unnecessarily. For instance today I exported about 2kWh because the battery was cold. But I put in 2.9kWh though a lot of it was used by the oven for lunch when the clouds rolled in.

Deagol

garo wrote: »

Yes the grant makes the economics slightly less favourable. I'd say close to break even. I estimated that I saved about 150 euro with my 2.4kWh Pylontech last year. YMMV. With the additional grant that 2500 becomes 1300 and your payback comes down to 8-9 years.

Re winter temps, when cold the battery charges more slowly though the discharge rate remains the same. If under 0 - which shouldn't happen in an attic - the battery should stop working altogether. Under 10C my battery only charges at 10A instead of 25A which means March and April I export unnecessarily. For instance today I exported about 2kWh because the battery was cold. But I put in 2.9kWh though a lot of it was used by the oven for lunch when the clouds rolled in.

Compelling reason to put the battery in the attic? I have mine in the upstairs of the garage and it loves it up there (it's insulated).

If it's going in the attic, would it be with the inverter? Could you use the inverter heatsink to heat an enclosure with the battery in it?

garo

I'd be more worried about heat in the attic. Solar gain can be substantial even in Ireland and keeping the battery at 40C is one way to reduce its life.

SD_DRACULA

garo wrote: »

I'd be more worried about heat in the attic. Solar gain can be substantial even in Ireland and keeping the battery at 40C is one way to reduce its life.

If it's the pylontechs should be easy enough to slap a few fans on the network rack they sit in for cooling and maybe throw the inverter in there too for heating during winter?

Deagol

SD_DRACULA wrote: »

If it's the pylontechs should be easy enough to slap a few fans on the network rack they sit in for cooling and maybe throw the inverter in there too for heating during winter?

You could put the battery at the end of a hallway and cover it with something so it looks like a table