Is north facing solar a complete waste

Snugbugrug28

https://www.boards.ie/discussion/comment/118424716#Comment_118424716

Fwiw I think you're absolutely right not to move forward. Too much risk, little reward. Points for considering it though.

bullit_dodger

Yeah, kudos for giving it a lash. I think you -could- get it to work, but it would be a pyrrhic victory. Blocked by vents, lack of ground mounting ability, north facing incline, high slope. There's a lot going against you.

The only thing that I'd swing back to is 5-6 panels mounted vertically facing due south could be aesthetically done, but would very much depend on your available surface area and what your tastes are like. Some of those jet black panels would effectively look like a horizontal band across the wall. I don't think I'd mind them, but sure not to everyones taste. Certainly not an eye sore like a satellite dish.

Manion

Yeah, I think It moves from being a sensible, practical measure to being a vanity project just to be able to say "I've solar". With the north facing aspect I was already looking into 25+ years for payback which was OK because, as mentioned, the Carbon death of the planet. Add onto it additional complexity from external and internal works it's just not feasible, I'm extremely weary of doing anything structural to a house that is only 5 years old. What I have learnt though is that Solar is definitely viable in Ireland if you roof is facing in the right direction. A south facing 9Kw system would have provider for 70% - 80% of our yearly usage and with a smaller system we could have simply worked around the vents. Payback period was coming out at about 10 years.

Regarding vertical mounting, it's just not a runner, aesthetically I don't think I'd like it but more importantly the agreement with the estate management company expressly forbids any modification to the front of the house without prior agreement, it's not really a fight I'd take on as I agree with the policy.

Long and Short - Is north facing solar viable? Maybe depending on your specific circumstances.

Thanks everyone for the advice.

bullit_dodger

Yeah - not for everyone. But at least you know it's possible anyway and have ruled it out. Would hate for you to not be at least aware of the potential.

I would think that should you want to do it that political motivation would be there with your estate management company. it's VERY hard to argue against someone wanting to do something environmentally friendly - as long as your not making some monstrosity, but you know your situation better than we do. Some of those jet black panels (not the ones above) look quite slick.

Markcheese

Even if you put solar on a south facing wall ,you're extremely limited to what power you'll get on a given day , and more importantly when you'll get it -

South facing on a verticle wall it's going to be middle of the day or nothing ...

bullit_dodger

https://www.boards.ie/discussion/comment/118426816#Comment_118426816

It's not as bad as you think. In winter it's quite beneficial as you've a great slant angle to the sun which is only really to the south anyway. It's summer where you suffer most ironically. Spring and Autumn are "ok". Yeah, of course if you want the best production you should be angled appropriately on the roof, but a few days ago we were contemplating north facing panels on a 30 deg roof.

Just saying.... :-)

unkel

Just came upon this thread again via one of the stickies. I'm up to about 11kwp now (small semi D house with a small garden in a Dublin suburb). Next phase is my virgin north facing roof, probably next year. Could probably fit about 4-5kwp on that too.

SD_DRACULA

https://www.boards.ie/discussion/comment/119159674#Comment_119159674

If only N would be worth a damn in winter when we actually need it 😂

celtic_oz

https://www.boards.ie/discussion/comment/119159674#Comment_119159674

Love to know how you are connecting or would connect all the panels to (multiple ?) grid tied inverters ?

the_amazing_raisin

https://www.boards.ie/discussion/comment/119159674#Comment_119159674

I'm guessing that only makes sense if there's a decent FIT or some way of making money off the North panel (like those crypto rig space heaters 😉)?

The issue with North facing panels is they only make sense if you've maxed out all the other roof space. At that point you're probably already overproducing in summer, in which case North panels won't help

If your garden is South facing then might be better to build a man cave out there and cover it with panels 😁

unkel

I've done all that already, @the_amazing_raisin 😂The only space I have left for panels is my north facing roof

Manion

OK, So an Update a year on. I've an installation booked for November.

It's been a weird ride, every supplier I contacted has tried not to take my money.

Spec

• 20 x 405 watt Longi hiMo panels

• 1 x 6kw solis hybrid inverter RHI-6K-48ES-5G

• 1 x WeCo 4kw battery 100% DOD

14K before grant - 11.6K After.

I calculated a payback range of 7-11 years at 90% consumption.

Every installer I contacted started out that because the system will only generate ~50% the power of a south facing system, it wasn't feasible/financially viable. But the sticking point for me is that I was quoted nearly 15K for a 6KwH system a year ago they all would have installed that no problem on an east/west or west/east aspect which has a much worse payback (Cost per unit 19Cent versus 14Cent for North). The power generation distribution is much more tightly packaged around the summer months compared to an east/west aspect but given our lifestyle it doesn't really matter when the power is generated as central heating isn't the big cost.

In the end my thinking was that if I would install a 6KwH system east/west then it makes perfect sense to install an 8 KwH system facing north that's coming in 3 grand cheaper. It's funny, all the suppliers the minute they saw the install would operate at 50% of potential wanted to walk away, people's thinking can very much so be path dependant.

So what about those vents you might ask? I'm unsure they where ever a problem tbh. After getting the mock drawings of where the panels would sit on the roof 3 of the 4 are just avoided and the forth is in the middle and there is plenty of space to leave a gap between the two arrays to not cover it.

Anyway, I'm over the moon with the prospect of actually getting this done. I'll post actual generation and consumption figures once it's up and running awhile. Thank you to the folks that provided feedback. It looks like the policy of "Just lash a few extra panels up there" is going to pay off.

unkel

What's your payback calculation? 90% self consumption is simply not possible with just a 4kWh battery, unless you divert to immersion with a large tank and EV(s) and have them always plugged in. But that's ok, we are getting a generous FIT now

Manion

Some figures based on consumption and generation. Only really have to worry about May, June and July. Shortfall is the amount I would produce from Solar and not consume. Assuming no battery or other sink that leaves 91.35% consumption.

Now, these are monthly averages and as we all know there can be serious fluctuations within the month. I don't know the standard deviation from one day to the next for my area so I cannot do a proper statistical analysis but assuming a normal distribution I decided arbitrarily that for 95% of days, production in a month will be within 40% of the average.

Based on that, in June (My best month) I could have a peak day of ~ 37.5 KwH and a peak shortfall of ~ 12.7. As you can see above my consumption is high generally, I'm trending towards 13K by year end. Now I have an EV with a 77.8 KwH battery that sits in the drive way every weekday and it's not a real issue to have it plugged in and charging off solar only (It's a Smart Charger with CT clamp etc). My conclusion is that with a battery capacity of somewhere between 8-12KwH and the EV, I'd probably never put anything back to the grid. I have asked for a price on another 4KwH battery, bringing me up to 8KwH and the beauty of the WeCo is that they are stackable. I need to strike a balance in terms of battery utilisation but running the numbers for the 8KwH versus 4KwH doesn't really add any years to the payback given the extra benefit of consumption shifting from the night rate.

I won't get an Eddie because I have a heatpump and DWH system and every time I look at it, it costs me two grand to get the one lad in Ireland who knows how the service the system out.

Now, the obvious flaw in this is what If I have several days of peak or near peak generation in a row. I've maxed out the battery in the house and the car is full charged or just not plugged in because I'm off living life. That's the bit I cannot really factor in at this point in time.

Maybe that's all mad though? I'll need to tune this a bit over time to get an optimal set up.

bullit_dodger

I'd think hard about that 2nd battery. One battery sure - makes sense to me to have a battery for "smoothing" output on cloudy days etc. but with FIT now giving you €0.13-0.14 / Kwhr for unit's that you export, you'll get some money for every unit that you don't consume in your EV and or house. So exporting is not the boogie man it was 6 months ago.

Agreed also with the Eddi. Doesn't make sense with a battery/heat pump. It would never pay for itself. Although that said, I do like the "free" hot water for 6-7 months of the year.

slave1

https://www.boards.ie/discussion/comment/119572986#Comment_119572986

If you are serious on battery I'd look to sell your current battery and put together a DIY battery from Aliexpress, you'll have lots of cash left over after doing this, just read through the DIY Battery thread, some learnings but if you are in any way DIY capable you can 100% put together a DIY battery....

EDDI is rarely economically viable but comes into it's own from a convivence factor and if coupled with other MyEnergi compatible products like Zappi or AC Battery Inverter

unkel

If you reckon you will self consume 90% with one 4kWh battery, surely there is no financial point at all to buy another one? 😂

As for an immersion diverter, it is cheaper to export any excess to FIT and then heat your water with night rate electricity or even with gas. So it will never pay for itself

Manion

Agreed FIT is an added factor though unfortunately it comes with the added sting in the tail of having to have a Smart Meter, and I'm sure someday being forced onto Smart Tariffs. I'm on a day/night meter currently which seems to offer great value and have shifted from about 20% night usage to 33% of power usage at night. I need to be more conscious of the fact during the winter months I'll not be generating enough power to be off Grid at the very high rate peak times. The main benefit from the system will be the consumption shifting.

Some quick Math at 10% export and Fit Payment of 18Cent I get 72 Euro a year. 4K Battery @90% utilisation through consumption shifting I get 198 euro a year (Though Obviously I have to buy the battery). However smart tariffs shift all this as the per unit cost is just straight up higher, what they give you on the FIT they offset against higher day, peak and night rates.

FIT is something I'll make a decision on once I have the system and can see actual consumption patterns. My goal is to see if the system makes sense while locking down as many variables as possible. I'lll not make a 25 year investment decision that was predicated on a high FIT.

‹Some more maths - Assuming an inflation rate of 4% for Electricity (Optimistic I think we would all agree). I get a pay back in roughly 7.5 Years at 90% consumption versus 9 years with a 60% consumption and FIT. All based on a baseline marginal unit cost of 27Cent in year 1. Payback looks basically the same for 8KwH Battery at 7.5 and I'm more likely to be at that idle 90% consumption.

Manion

https://www.boards.ie/discussion/comment/119573581#Comment_119573581

Sorry my sentence structure was a bit rough, I think I would hit 100% self consume at somewhere between 8-12KwH battery provided I'm smart about the EV during summer months.

As you say, absolutely, not going with the Eddie, the Heatpump does DWH and I've it timed to kick in just before the night rate ends, when it draws most power in the shortest time.

https://www.boards.ie/discussion/comment/119573560#Comment_119573560

There is a confidence things about it. I totally get there are ways to do DIY and get a much better battery set up, and I may tinker around with it down the line.

slave1

FIT is admittedly a lot better than we anticipated but hard to judge exactly due to Energy Crisis's impact on pricing.

Disadvantages of FIT versus Battery (for me)

Brings Smart Meter into play

No EPS backup

I will remain on the fence on FIT, I also have a battery already so a sunk cost, let's see how this plays out over the next year or so

Will FIT stay as high as it is or drop after a few years like other countries? I wouldn't be confident of them not dropping, so a battery pack is essential imo.

I'm also skeptical about FIT as the energy companies are offering a decent FIT on one hand, but gouging on unit prices on the other.

Also regarding an Eddi. With the price of oil and gas, the Eddi is a decent investment. It's not too expensive. I've barely used oil to heat water since the end of March. If you use immersion to heat water then even better.

unkel

@6 - "the Eddi is a decent investment"

It really isn't. Unless the FIT falls below the night rate price, you actually lose on every single unit you send to the Eddi. Never mind never recouping your investment.

And I hear you say: we don't have any FIT yet. True, but you are not entitled to deemed export if you have hot water diversion. So you are losing out there too

I was planning to install an Eddi too a few months ago. The only reason I didn't is because I couldn't get one new. I bid on second hand ones, but I under bid. Then the FIT rates were announced and I dropped that plan like a brick. Makes far more sense to just export your excess and get FIT and then heat your hot water with night rate (which is lower)

I agree with your concern about what will happen to the (current) high rate of FIT...

DC999

And on the Eddi, there're several 'losses'

• PV is way less efficient heating water than other sources. So costs more 'PV' to heat it
• Can't self consume that juice (home, EV, battery, or get paid from FIT for those units) once in tank
• Pumped showers (instead of electric ones) use heaps more water per minute than electric ones (some places I've read said 3-4 times, so 20+ liters a min v 5-6 from electric). So the energy used is 3-4 times more (for that hot water). Not best use of water either. Granted you can get the shower head to reduce the flow rate
• Water tanks lose heat that you've 'paid' for in PV to heat. Ok, the new, good (very expensive ones) can be like 1C heat loss a day some here suggest. But they cost a lot to supply + fit. And larger ones to better hold the heat need a lot of space (we're in a small house)

I was gonna get an Eddi and new htw tank + pumped shower but cancelled at last minute. I totally get we still pay for electric showers (have no battery). But it's 'on demand' heating. So only pay for what we use. In an ideal world I'd have heated water from solar. And I totally get the convenience of hot water when needed (we don't have that now bar electric shower). But with a small roof (so small PV setup) and small house and small budget (post solar and 2nd hand EV), the Eddi isn't best bank for our buck.

Redlim

"And I hear you say: we don't have any FIT yet. True, but you are not entitled to deemed export if you have hot water diversion. So you are losing out there too"

@unkel - Am I reading the above correctly? If I get a solar PV installation done that includes an Eddi then I wouldn't be entitled to any FIT repayment? If so, is this for everyone or just those without smart meters? I'm on a day/night meter so this really could make a big difference.

I'm guessing "deemed export" applies to non-smart meters where it's just an estimate of what you are exporting?

slave1

Heating water at night rate is all well and good but when two daughters decide to have a hair wash they drain the 240L tank. I'm not waiting for the night for more hot water so for me it's a "convenience" investment as arrived home today with tank maxed again.

Horses for courses

graememk

https://www.boards.ie/discussion/comment/119590635#Comment_119590635

"PV is way less efficient heating water than other sources. So costs more 'PV' to heat it"

Hmm.

Pv is way less efficient than solar tubes.

But once it's electric it's the most efficient way. 100%. (Well maybe 99, nothing is perfect)

Heating dhw with oil or gas hopefully should be in the 80-90% range. But as the water gets hotter, the lower the % is.

Can't consume.. well a eddi (other hw diverters are available) is last on the pecking chain for power before export.

If on a day night, well your exports not measured.

If your on oil, at the present prices. An eddi becomes a whole lot more appealing.. but every house is different

my house doesn't have any electric showers. Both are run from a single boost pump. I shower in the evening, because farm.

Present price of oil is about 1.40, divide that by 8.5 (85% efficiency) get you 16.4

So every kwh you put in via an eddi is saving 16c. Eddi costs 500, you would need to pass 3000 odd kwh through the eddi. That's the payback period for it.

I wouldn't be ripping out showers etc just for the eddi though.

That all being said. I don't have an eddi on my DWH - lol I have a 20 euro smart immersion switch that comes on at 12pm every day if the tank is cold via home assistant and knocks off when the tank gets hot. Sure some might come from the batteries but I'll live with that.

.. and my oil isn't plumbed into my dhw either, just the stove so I'm an edge case there.

Just want to clear up, having an eddi doesn't effect a fit at all. Except if your on a smart meter.. you will just have less export.

Day night your getting a flat "deemed" export

@unkel

@unkel Heating water at cheap 6c night rate is great, but what if it's 20c? Some smart plans probably aren't far from that.

Plus when you've a bunch of kids having showers at different times of the day and evening it's priceless.

Btw, that's the first I heard of no FIT for people who have an Eddi, or am I reading that correctly? It wouldn't be bother me too much, but it might others. How do they police that? Edit, this is explained above.

bullit_dodger

https://www.boards.ie/discussion/comment/119591670#Comment_119591670

It's not that it's "No FIT you have an Eddi", but you don't get to reap the FIT export for those specific units because you consumed them in the immersion if you follow. As in you can't get paid for electricity which you otherwise consume in the tank :-)

https://www.boards.ie/discussion/comment/119592006#Comment_119592006

That only applies to a smart meters though? Plus, you'd be paying more for units so how much you'd actually be making net is minimal. In my case anyway.

unkel

@graememk - "Day night your getting a flat "deemed" export"

With Airtricity SSE, the letter specifically said you were excluded from deemed export if you had an immersion diverter. I presume it is in the small print of some or all the others too. So you get nothing, not a cent in deemed export. Of course you could lie about this, chances are they'll never find out. But that's fraud all the same.

@graememk - "So every kwh you put in via an eddi is saving 16c."

Every kWh you put into your hot water is saving only 7.9c if your night rate electricity is only 7.9c. Same for an EV diverter

How wouid Airtricity know you have a diverter if it was installed post solar installation for example?

slave1

They won't, no difference between it an an immersion, or oven, or kettle or toaster etc

slave1

https://www.boards.ie/discussion/comment/119592116#Comment_119592116

Jesus, that's unbelievable!!!

idc

https://www.boards.ie/discussion/comment/119592116#Comment_119592116

Thats crazy sure you could fill your car with all your export instead? Are they excluding Zappi or similar car chargers as well??

slave1

Or Miners

graememk

https://www.boards.ie/discussion/comment/119592116#Comment_119592116

That's mad with sse, they have no way of knowing if you have a diverter or not.

Re savings, vs oil.

Debated that cost oil or night rate before posting.. I know we have 8c night rate but a lot of others don't. It's pushing 15c for normal DN plans.. even 20c!

And if the eddi replaced oil directly.. it's 3000kwh.. and done nothing else.

Next step would be to heat it on night rate, great for morning showers.. not great for the evening but should be enough.

I'd be putting it squarely in the nice to have category. Before I got the smart switch in, I just hit the immersion timer button at lunchtime. (Tank is preheated via solar tubes)

unkel

Hot water is the one thing I think I am getting under control (without automation). Enough through the immersion to have roughly enough for the day and the family can top it up where needed through the nest app (through the gas boiler) for when the solar thermal doesn't assist enough during the day and people want a long shower / bath. This changes of course per season. During the 3-4 summer months I get nearly 100% of hot water through solar thermal unless I get a couple of bad days in a row. And we use a lot of hot water

Gerry

Yeah I'm still on the fence re eddi. If I can get a decent night rate ill just time the immersion. electric irelands night boost might work out better than sse current smart tariff.

unkel

@Gerry - have you a smart meter and are you on a smart tariff? Then what are your rates for night / cheapest and what is your FIT? Or are you about to change contract? And how big is your PV array? The answers to those questions will determine what's your best option from a financial point of view

Gerry

yes, smart meter. lets say that the night rate is 30% less than the day rate. so about 24c. FIT is 14c.

4kw pv total.

https://www.boards.ie/discussion/comment/119593299#Comment_119593299

Night rate is 24c? That's mad.

slave1

https://www.boards.ie/discussion/comment/119593299#Comment_119593299

Think about switching to Energia EV package which has much lower night rate, Energia will arrange for your Smart meter to be replaced with a D/N meter

randomname2005

https://www.boards.ie/discussion/comment/119593648#Comment_119593648

As in retrofitting a 'dumb' meter and taking out the smart meter or just using the smart meter capabilities of charging different rates at different times?

Gerry

energia already offer a low night rate via smart meter. I think taking out a smart meter is a bit nuts, when there's nothing stopping smart meter night rates getting more reasonable, and day night meter rates less reasonable. probably this is the wrong thread ill post a comparison on another thread.

unkel

I agree that having the smart meter removed for a day night old skool meter is ridiculous, but it's what the utility companies are forcing on us with those sill smart tariffs. If I were you @Gerry, I would consider doing just that.

Manion

You look away from a thread for 2 minutes :). So I'm not getting an Eddie because on top of getting an Eddie there would a be a plumbing costs. The cylinder is fitted with two emergency mode immersion heaters in the event the heat pump has an issue but all that sounds very dubious to mess with.

My night rate is 11.72 Cent including Vat after discount and my day rate is 24.43 cent. I pay a slightly higher standing charge. The prices you're paying @Gerry are insane, but maybe I just got a good deal at the time. Interestingly I broke out of a contract with Bord Gais to go with Energia and they never charged me the break fee.

bullit_dodger

https://www.boards.ie/discussion/comment/119594456#Comment_119594456

I no expert in HP's, but I believe most of them have a resistive heating element in the tank so that once a week or so it can use that to heat the water up to 60+C to stop legionella? So you should already have an element in place inside the tank which you can use for the Eddi.

Now the financials of an Eddi is another thing, but I think you probably don't need plumbing?

Gerry

Yep, you could most likely wire in there, it needs a competent electrician who is familiar with all of these things.

Just to correct re the rates - I'm currently paying 18.4c night rate. After SSE increases it will be 22.8. They did not hike the night rate by the same amount , it was 24% of course, they should not have hiked it at all ).

Manion

https://www.boards.ie/discussion/comment/119594855#Comment_119594855

Correct, but the Eddie is definitely not going to pay for itself coming on once a week to heat the tank up by 15 degrees from 45 degrees to 60 degrees. Theres two control systems here and the Eddie is just a fancy emersion switch, the DWH tank control unit would need to be convinced somehow to draw power to heat the water as opposed to using the HP to do so. Even if I was inclined to figure out a way to do that, it's even more cost effective to use the night rate to heat using a heat pump. For every unit I put in I get 3 units for "free". So it costs me like 3 cents a unit to heat my water at 7am using the HP. Long and Short an Eddie isn't a smart move for me.

DC999

Hey @Manion, it the north facing setup live now? Curious, in a positive way, on the numbers from it. Ta