Solar PV Hints, Tips & Troubleshooting

bullit_dodger · 18-03-2022 8:56pm

Good questions cloughy. Not really the right thread for it, more of a "PV Tips and Troubleshooting" but hopefully one of the mods will move this.

So first off, I'd be very slow to get rid of your evacuated tubes. You can think of it as a "sunk cost" and it's doing it's job (i.e. heating water). A little bit of a side point, but evacuated tubes capture ~50% of the suns energy which falls on a sq meter, while even new solar PV panels capture about 20-21%. So in terms of pure efficiency the evacuated tubes are pretty good.

That said as you say, it's old tech and while the PV panels aren't as efficient in terms of energy capture they have substantially reduced in cost over the past decade to the point that I'd say there are few and far between evacuated tube installations anymore. You'd just bang up more PV panels on your roof and you have the flexibility of powering you house as well as heating your water. So if you were starting with a blank roof I'd just go PV panels and forget about the tubes.

Since you have tubes already, I'd look at what space you have left. How many sq meters you have on that roof, and of course if you have east/west roofs they will also work for PV, doesn't have to be south facing (although obviously that's preferrable). Even north facing can be beneficial too (esp if the slope of the roof is fairly flat)

System · 18-03-2022 10:57pm

Moved from quotes page.

Jonathan · 18-03-2022 11:45pm

https://www.boards.ie/discussion/comment/118803260#Comment_118803260

I have both PV and thermal and my advice would be to keep your evac tubes if they are working well. Heating 1000L water from 20C to 60C requires over 46kWh of energy. You'd need a big PV array and lots of sunshine to heat that; Remember that thermal is considerably more efficient per m2 of collector area compared to PV. How much space do you have remaining on the south facing roof for PV?

See my reply to someone else last week in similar situation: https://www.boards.ie/discussion/comment/118734925/#Comment_118734925

Also: is there any reason why you aren't using the 1000L tank as a thermal store to offset your heating requirements during spring/autumn?

cloughy · 19-03-2022 11:03am

thanks Jonathan for the reply, regarding the last point we dont have the heating on during those months, as no real need due to the levels of insulation, but the tank does feed underfloor heating as far as I am aware, but 100% sure on how it all works together.

I dont know how much space is available on the south facing roof, but as starting to think about PV wanted to get some thoughts before unleashing Solar sales reps on us.

When you put the PV panels did you also get the eddi to top up your hot water in addition to your solar tubes, so are you just generating electricity/battery storage.

For a 4 person house, consuming circ 5000kWh a year at the moment, what size system would be required, as I know its better to go bigger if possible due to reduced panel costs and doing it at the one time.

If you or someone could give some advise so we know what to consider when we get quotes, and obviously we will post them on the other discussion to see how they stack up. We are in South Dublin

THE ALM · 19-03-2022 11:16am

https://www.boards.ie/discussion/comment/118796318#Comment_118796318

bit of noise of it alright at the highest fan speed setting but once lowered it is not too bad.

Jonathan · 19-03-2022 11:40am

https://www.boards.ie/discussion/comment/118804848#Comment_118804848

I have an Eddi as well. During the dull months, the thermal acts as a preheat for the immersion which is half way up the tank. During the summer months I'll turn off the Eddi and let the thermal heat the entire tank.

I guess the decision to get an Eddi depends on where exactly in your cylinder the immersion is located. If you have two, all the better; the Eddi can heat the top to temperature and then switch to the lower element.

I had to relocate my tubes to a different south facing roof in order to accommodate the PV as I couldn't fit enough around them. If I could have left them in situ I would have.

paulbok · 19-03-2022 11:46am

On the other discussion, throw up a photo of your roof showing what's already up there, will help to gauge what can then go up. The tubes will probably determine/limit the size of PV can go on.

From there the rest of the system (inverter size, if battery is wothwhile) can be worked out.

Mention again the direction that roof faces and general electricity usage pattern, e.g. Working from home, high in mornings for showers. Anything that might throw shadows on the roof such as trees, neighbours chimneys etc.

Ultimately you'll need to make your own decusions on what you get, but you'll get plenty of good advice on here. I am very happy with the direction I was steered, installer recommendations and ongoing support to make the best of your system.

Jonathan · 19-03-2022 11:52am

In other news, it appears that myEnergi are releasing a WiFi/Ethernet capable Zappi. Little information yet on their website other than the banner on the homepage.

THE ALM · 19-03-2022 12:20pm

https://www.boards.ie/discussion/comment/118805004#Comment_118805004

would make sense to integrate the hub into the zappi and take out an additional piece of equipment.

jobbr · 19-03-2022 7:21pm

Hi all

New-comer here, hoping for some advice.

I currently have a Solis RHI3.6K-48ES invertor connected to 3 x Pylontech batteries (2 x US2000B and 1 x US2000C). It was installed when I bought the house (I added the US2000C in summer last year) but our installer is London based and struggling to find somebody local who knows our the Solis gear. We don't export anything to the grid.

We're on Octopus Go paying 15p/5p, but this is jumping up to 28p/7.5p in April.

I want to try adjust our system so that it will fill the batteries from the grid overnight to last us between 0430 and 1100 when the sun typically hits the panels & generates enough to cover the house's use.

Is there any guides on this around the forum? I've been Googling, but everybody seems to have different menu options etc. Our HMI version is 12 which seems a little out of date, but not sure on best way of getting that updated.

Any tips / pointers appreciated!

Cheers

JB

The devils · 20-03-2022 10:52am

Guys

Can anyone tell me what DC voltage you would expect to get from a 12x370w panel ?

Should it be less when dull and more when sunny ?

I'm currently reading 337 volts for sunny side

And 411 for dullish side

Thanks

graememk · 20-03-2022 11:32am

https://www.boards.ie/discussion/comment/118808632#Comment_118808632

Usually the opposite. The less load on the panels the higher the voltage, voltage and current that is power

The inverter is mppt or maximum power point tracking. It balances the voltage and current for maximum power out of the panels

cloughy · 20-03-2022 9:10pm

hi all, I attach some photos, one of the south facing roof that has the 7.5sqm tubers, and also the water tank, its 500L I think, and it has 2 coils in it, S4 and S6, S6 at the top, and S4 the bottom section, and today the tubes were circ 55c and the temp in S4 and S6 was over 50c so lots of hot water for showers, washing etc.

You can see the remaining roof, not sure how much is left on the south facing, but appreciate peoples thoughts on if its a runner. We are 4 in total, one at home all the time, and I work from home 3 days a week, we have a pumped water system so hard to use DW/WM overnight as the pump runs and is noisey, but we use about 5000 units of electricity a year, but may replace boiler with a Heat Pump and may add an EV in the next 12 monts.

Here is ariel view of the house.docx

controller S6 zone.jpg

How watertank picture.jpg

Hotwater tank drawings s.jpg

Hotwater tank drawings.jpg

bullit_dodger · 20-03-2022 9:28pm

Your pictures and info really help.

Well, you've massive east/west roofs. You are well suited to use those for PV panels, and I'd leave the existing solar thermal alone. Assuming it's working away and heating the water, then it's "doing exactly what it says on the tin".

East/west roofs typically generate 80-85% of the capacity of a south facing roof, but while the capacity is lower, East/west roofs have certain advantages over pure south facing roofs. Instead of having one large peak at noon (with a south facing roof) if you have your panels split over east/west, you get two lower peaks. One in the morning about 10am-11am, and the other in the afternoon about 2-3pm. Your generation is more stable for day, albeit at a lower level. This generally isn't a problem as most of the production you generate goes into a battery anyway. Infact it can be advantageous as you tend to get power production earlier in the morning (breadfast) and later into the evening (dinnertime) - which can be useful if there's no on in the house at lunchtime.

With the house using 5000 units of electricity I'd be inclined to get 6Kwp in panels.

10 panels (380 watts each) on the east roof amounting to 3.8Kwp and
6 panels (380 watts each) on the west roof amount to 2.28Kwp

Why the disparity? Well according to your ariel view, assuming it's orientated north at the top your east roof (slightly) faces south by 10 degree or so, so it would make some minor advantage to have the bulk of your panels on that roof, but really 10 degree ain't going to matter much. You could equally split them 50-50 too.

AndyBoBandy · 20-03-2022 10:11pm

https://www.boards.ie/discussion/comment/118792600#Comment_118792600

Yeah, I picked up one of these today, grand job altogether… and will see a lot of use given the production levels from here on…

Jonathan · 20-03-2022 10:26pm

https://www.boards.ie/discussion/comment/118811304#Comment_118811304

As @bullit_dodger says, leave the thermal system alone. From the aerial photo supplied, it doesn't look like you'd get many panels up in place of the collectors anyway once you factor in the SEAI roof edge clearances. Fill your roof with PV E/W and you'll be sorted.

It isn't clear from the cylinder diagram if it has an immersion or not. I suspect it doesn't, and in that case, that is the decision made on the eddi for you.

cloughy · 20-03-2022 10:32pm

yes thats what I think E/W array is the only real option, so not sure what I could put up, or what should think size wise, so any suggestions please let me know.

Regarding the cylinder, I dont know it if has an emersion, but I am able to heat the water from the boiler, via the Motorised valves, but from what you are saying, are you suggesting that the Eddi is or is not an option, assume not since it is boiler driven to hear the water rather than electric.

Jonathan · 20-03-2022 10:40pm

https://www.boards.ie/discussion/comment/118811605#Comment_118811605

We swapped out our gas hob for induction when we were replacing kitchen a few years ago. Was the time to do it as the induction hob is rated at 7.4 kW and needed a new 6mm2 feed from CU. Solar PV wasn't on the radar at that stage, but glad we did. You get very accustomed to boiling a kettle at 3.7kW. 😎

I actually need to get a cheap kettle for the EPS socket in the event of a power cut.

Jonathan · 20-03-2022 10:58pm

https://www.boards.ie/discussion/comment/118811692#Comment_118811692

No immersion = no eddi. Unless you want to get some sort of Willis (external) immersion, but that is a bit messy and would require a plumber. You'd also need a 16A circuit from CU to cylinder. Not worth it.

bullit_dodger · 20-03-2022 10:58pm

https://www.boards.ie/discussion/comment/118811692#Comment_118811692

The question of an Eddi is somewhat made redundant if your hanging onto your existing thermal solar (which I think you very much should). You've got a good working system there, doesn't make any sense to remove it as mentioned and the Eddi would, at best, only equal what you have......and in reality would probably not equal it in terms of heating water.

No, drop the Eddi out of the equation for the PV installation. Considering your 5000 units per year, 6Kwp in panels, coupled to a 5Kwhr battery would be a good shout out. Should be in about the order of €8500-€9000 (assuming you qualify for the grant of €2400), if not then you'd be talking about €11K.

Good solar forecaster that people use here is.....

https://re.jrc.ec.europa.eu/pvg_tools/en/#PVP%20that's%20the%20calculator%20for%20Europe,

You can select your location on the map and input your details (you'll have to do it twice as you have an east west layout) and it will give you the expected yield per month.

connesha · 21-03-2022 1:00am

@Jonathan , about the storage heater linked to Eddi from the other thread:

I installed it mid last week, purely for the purpose of Solar excess. Like a lot of people here, it was killing me seeing 10 or 15 kwh exported lots of days, and then paying for oil 2 hour later.

In my case, I got lucky in that a family member had taken down a used one in good condition a few years back, and they had kept it since. And I had half a roll of leftover 2.5 NYM in the shed, so the sum to total of cost was the 7 euro for the isolator switch/fuse (and half a day of my own time), so it was worth as an experiment at least.

Cost wise, yea, they are very expensive. Can be 1k new, and some of the newer ones have additional (fancy) controls in them so may not be 100% resistive load. If I didn't have that one, I'd definitely have bought second hand from adverts/donedeal. I was watching them before i got solar even, and saw some go for 100/200 euro, which seems in the reasonable ballpark for this purpose.

Mine is a Dimplex Unidare 2.4kw. From the past few days usage, that seems like a reasonable rating considering you want it large enough to give some real heat, but may struggle to fill more than that in days you actually need it (Full is approx 7 or 8 hours @ rating)

The heat it gives out is slow-release, and more of a background heat. Over a period, it'll take the chill out of a space, and keep the temperature steady. Its very different to the plug-in ones that give instant heat. I've mine in a corridor between the bedrooms.

In the few days so far, I'm finding it the perfect companion for solar:

It charges during the sunny daytime when you don't need heat, and releases in the evening when you do.
It's as fully set-and-forget as you want it to be when hooked into Eddi.
Since its Eddi-controlled, you're at less risk of going over your inverter output max compared to a plug-in solution (unless you have your own super tight automation). Consider when other appliances are coming on/off, or washing machines/dishwashers which have long cycles and load comes in bursts.
And if you get the daily forecast wrong and over charge your battery at night, at least your excess has somewhere useful to go.

Also, now that its hooked up to the Eddi, I'm thinking of using Boost Timer for charging it next winter on night/EV rate, for morning/daytime release, if night rate electricity is considerable cheaper than oil.

Cons:

I've lost the sink output on Eddi, which I used to boost every once in a while. Could put a bath/sink switch between Eddi and immersion to get this ability back, albeit a little more clunky. Could also do it with relay, especially if wanted for any automation reason later.
They are quite big, and I wasn't allowed to put it where I originally wanted. But around the corner was finally accepted.
Some people may prefer more heat output quicker (but also, slow-release may be preferable for others)

And for a next project...

Its also quite interesting from an automation perspective. It can be treated essentially as another battery (for a different type energy), so most of the logic for battery topup/mgmt logic could apply to it (similar for cylinder+immersion too)

It can be charged
it discharges over time,
it can have an SOC (rough: input brings up, time brings down. Better: install a stat).
You have a certain "usage" need over a day (can be linked to temperature/wind weather forecast).

Thats all probably completely overkill, and a simple "charge at night in winter if electricity cheaper then oil" rule may suffice, but maybe a fun addition to existing automation...

Note to others thinking about it/disclaimer: I'm not an electrician. Be very careful with the heater that's chosen. It needs to be 100% resistive load. If its got anything that looks in any way sophisticated, you don't 100% understand everything inside it, or are not competent to do it, then get a REC. And make sure its got an isolator and appropriate fuse.

paulbok · 21-03-2022 9:39am

If you are considering a heat pump and/or EV in the near future, it would be worth filling both sides of the roof with as many panels as you can.

11 on East, 10 west, would give you a 8kWh array, the max I believe a 6kWh hybrid inverter can take, though as it's an E/W split, each with a lower potential than a purely S facing array, it would be unlikely to ever output that 8kWh.

Others could advise if it'd possible or worthwhile to add even more panels if space permitted. You could possibly go up to 24/25 panels if it is.

Jonathan · 21-03-2022 11:44pm

https://www.boards.ie/discussion/comment/118812237#Comment_118812237

Thanks for this detail. Definitely an interesting project. I don't suppose you have another 16A supply nearby to your Eddi? You could use the relay board to control your storage heater, and free up the second output for your sink element again. Obviously wouldn't be a variable output, but on the days that you'd be using it, you'd likely have generation well in excess of the rating of the storage heater.

The oil radiator working well for us at the moment. The heat loss in the room very manageable so I don't think it warrants the effort/cost right now.

ELCAT2009 · 22-03-2022 11:37pm

https://www.boards.ie/discussion/comment/118806774#Comment_118806774

What times do you want it to start charging from. I have 6kw Solis inverter installed in Nov so could try and post steps I would do on my inverter. Might not be the same for your older inverter🤔

On separate note, was it easy to add the US2000C to the US2000B batteries. I currently have 2 x US2000B and I want to add another. A supplier another boardsie recommended has US2000C batteries in stock. I read somewhere else the CAN cables are different?

THE ALM · 23-03-2022 1:06pm

This fine weather has me looking at everything electrical to use as much as possible and have started down the automower options. Filled the petrol can and now taking €22 to fill it😮 not long ago when it was half that.

Trouble is we have about an acre to cut so getting into pricey mowers at that level.