Self consumption percentage?

the_amazing_raisin

I was wondering what kind of self consumption amount people are getting and whether they're using a battery or not.

Seems to me with a battery sized around 10-15kWh and a 6kW inverter you could probably self consume close to 100% of your solar, assuming you've enough panels to feed it.

If anyone would like to post what they're getting and whether they're using a battery or not that would be great, thanks!

SD_DRACULA

Here's a few values 6kwh hybrid with 7kwp of panels S facing (live since 05/2021)

Up until April 2022 I had 5kwh battery and 20kwh after that so you get some decent values.

My average monthly usage is about 600-700kwh

Not sure if these figures are skewed when night charging in the Solis app as that looks like it's counted as generation but even so I only put about 200kwh into the batteries since start of October so it won't be massive.

2021

2022

DC999

Very good Q and will be interested myself to see replies. Only live 3 months so still learning myself and we’ve no battery. Some interesting numbers from @SD_DRACULA with a large battery - I've battery envy now :)

We’ve 4.9kWp in Dublin 12 so we’ve a small setup relative to others here. Split is: E 55%, S 25%, NW 20%. Which gives us a decent spread over the day (but the NW dies on it’s backside this time of year and E/W suffer from low sun too). And we’ve less output than a South.

I’m WFH. We’re a low energy usage house and have been for years. So our average is about 350kWh a month (for house and EV, excluding gas cooking and heating)

Self-use (no battery so always a challenge): 36% Aug (just setup so not making the best use of it and lot of sun), 44% Sept (less output so easier to increase % used), 47% Oct.

Am running some low-watt electric heaters to keep boiler off and they run from solar mostly. That helps self-consumption and heating will kick in more as it gets cooler.  Bear in mind as output drops this time of year, it’s easier to increase the % of self use. I’ve no automation and if I stay without a battery (which is likely), I’ll go down that route (to start / stop devices when there is excess). Automation from what I’ve seen takes a lot of time, but will save me the cost of a loan for a battery. Or I'd go DIY battery route possibly. Goal would be to reduce the usage on the peak TOU tariffs when we do get a smart meter.

For us, the only time we can get a high % of self-use (like 60%+) is when the EV is in the driveway in sunnier months. Our EV only has 25+kWh battery (which is small) so it fills quickly as it's not used much (so doesn't need much to fill). But it was charging mostly from solar to maybe mid-Sept. Not a change it can charge from it now. A large EV that is used more would ‘soak’ a lot more (if in the driveway when the sun shines). But that won't be your 'battery' until we get more sunshine in spring.

the_amazing_raisin

Thanks guys, looks like a well sized battery can really help out with the self consumption percentage

My main goal is to balance the battery size so that my self consumption is over 80% and most of the import from the grid is on the night rate

I think for me the sweet spot is around 20kWh but that seems like overkill for now. I'm probably going to get the system installed with a 13kWh DIY battery for now and ask the electrician to leave space on the busbars for another battery pack or two (hopefully I'll never need more than 39kWh or storage but you never know 😅)

I'm still chasing people for quotes but at the moment I'm thinking of 6kWp of South facing panels, 8kVA Victron inverter and 13kWh DIY battery. We'll see how it goes with that

ELM327

I don't have the specific software to monitor but with 8.2kWp and 20kWh of storage (and my determination not to export) we're likely exporting almost zero

graememk

Heres my numbers.

Some notes. 8.6kwp, NE/SW. Low slope. 10kwh battery in 21, 20kwh in 22

Discharged battery most nights this summer. stopped in sept. (counted in the %, I could remove that...)

Also the upcoming months, Im charging the battery to 100% now every night and letting the excess go to the tank. That started in sept too, hence the lower self consumption.

Some allowance has been made also in the summer months for the auto immersion boost.

I'll do up another list with diverts included.

(was in holiday in May)

the_amazing_raisin

I'm guessing the lower consumption in summer is because you're exporting more to the grid?

I heard someone say recently that you can't consume everything you produce, but with my usage I feel like I can get close to 100%

I recently updated my figures for getting solar and the payback period came out at 5 years. That'd be pretty awesome, but it's probably also a tad optimistic.

The basic assumptions to make that happen are self consumption of close to 100% and shifting 85% of consumption to night rates.

Still chasing people for quotes though, too many people interested in solar at the moment 😭

Manion

Of course you can consume 100% of what you produce, that doesn't mean it's a good idea. Getting that last few percentages is likely not to be cost effective depending on your circumstances.

the_amazing_raisin

https://www.boards.ie/discussion/comment/119819797#Comment_119819797

Yes, absolutely true. I feel like I'm coming from a position of high consumption (10,500kWh last year) and I can probably only generate 6,000kWh per year.

I've also got 2 EVs in the driveway to soak up excess. So while 100% self consumption is probably not worthwhile, I feel like high 90% should be feasible in my case

yankinlk

My Solis gives me these numbers:

My system is 6.5Kw East/West with a 5Kw battery. If I add in the Eddi usage this year (not full year) of 454Kw then my self-usage goes up to 83% on the generation side (i subtracted the export for eddi from energy exported). On thw consupmption side it adds another 3% so total 59%.

For the energy imported - I have to estimate what percentage is going to night rate... im showing 61% since last year on the total units - but I have noticed the numbers are improving with better habits lately (not just mine - everyone in the house). October for example is at 75% night usage.

If i look at where i was BEFORE solar - i was consuming 8500Kw per year on a STANDARD RATE - never switching suppliers either. Now im down to paying standard rate on a little over 1Kw per year.

yankinlk

I am ruthelss btw with using sunshine - and I have help with multiple poeple working from home to turn things on. I have also invested in some smart plugs so I can turn stuff on when i am not at home if i want. But i still think i wont get lose to 100% self use.

idc

Before I quote just confirming the equation to calculate self-consumption (1 - FeedIn/Generation)*100 ?

the_amazing_raisin

https://www.boards.ie/discussion/comment/119819903#Comment_119819903

Thanks for that, are you charging the battery overnight with the night rate to supplement it in winter? Or are you still filling the battery from solar at the moment?

https://www.boards.ie/discussion/comment/119819944#Comment_119819944

I think having someone in the house during the day definitely helps. You can set the washing machine and dryer to some on when the sun is shining and cook some dinners around lunchtime to make full use of solar

yankinlk

https://www.boards.ie/discussion/comment/119820093#Comment_119820093

Yes to both comments. I started October trying to manage battery charging - somedays 50% other days 70% or even 100%. BUt I give up now = 100% every night... there were not a lot of great sunny days in October and im sure there will be LESS in Nov. :P

bullit_dodger

12 months ago, a high self-consumption % was a good thing. Now I think with FIT..... it's sort of a moot point. In some respects, even the stuff you export is self-consumed as in your getting "value" for it....sort of the same way as a unit of energy that you use during the day at day rate or put into the battery to consume at night rate even.

In that respect we're all at 100% every month now. (if you look at it that way)

DC999

https://www.boards.ie/discussion/comment/119820235#Comment_119820235

Yeah, and with 2 EVs in the driveway I'd suggest don't get a battery now. Wait until your solar is setup (think you're still waiting on the install OP). I'm glad I didn't get a battery at the start as I can find my way with it (only live 3 months).

Ok, EVs won't help at this time of year as there is no excess to send to them to get the self consumption up.

yankinlk

https://www.boards.ie/discussion/comment/119820235#Comment_119820235

the only reason i disagree... is that im still waiting to hear from Electric Ireland about ANY payment... so I assume nothing. I switch in March - and I will be certainly taking into account the companies that make it easy to receive the FIT that is owed. (that rules out BG for definte - and so far with a total lack of transparency in my case - EI for sure as well.)

SD_DRACULA

Don't forget if you are on deemed export you want to be exporting close to 0 and still get paid for it - sorry Greta 🤣

the_amazing_raisin

https://www.boards.ie/discussion/comment/119820235#Comment_119820235

At the moment I disagree, since I don't have a smart meter so any FIT will be estimated. I get the same amount regardless of whether I export 1000kWh or 0kWh

So to me, it's better to self consume the max amount that's reasonable and take the FIT as free money

Where we're all on smart meters and export is metered then I think the case for not having a battery will be much more clear cut

the_amazing_raisin

https://www.boards.ie/discussion/comment/119820281#Comment_119820281

I'll be getting a battery anyway because I want some sort of backup power supply. I use electricity for everything so consequently I need some security of supply.

Had a power cut recently and the house is basically reduced to preindustrial times (actually worse because a 19th century house would have a fireplace)

But there's definitely a case for getting a smaller battery at first and then seeing how it goes

the_amazing_raisin

https://www.boards.ie/discussion/comment/119820376#Comment_119820376

I don't think self consumption is necessarily worse for the environment, unless you're using a diesel generator to generate your power

The difference is that if you're exporting you're giving solar power to your neighbours. If you're self consuming then you're using it yourself. Either way the same number of kWh gets displaced from the grid

Okay there's still the evening peak, but I don't think export is going to fix that. If anything more self consumption is better for removing the peak

idc

With FIT as high as it is then self consumption doesn't make as much sense as it did before. For me 2022 jan/feb is worse as i was load shifting hence i probably filled battery too much and then exported during the day. Later months i doubled battery to 10.9 kWh and also got an EV which most of the time is on minimum charge thus my export is kept low. when i end up on smart meter and if FIT stays as high as is relative to night rate then likely I will export by day and charge only at night! hence self consumption will not matter so much

bullit_dodger

I get the arguments @yankinlk , @the_amazing_raisin , @SD_DRACULA and I agree with you all. I'm actually on deemed export myself, but with the move from SSE -> Energia (outlined in the FIT thread) SSE are saying they won't pay me for feb -> Sept for the deemed export that I would have had with them without me getting a smart meter going forward - even though I'm not with them anymore.

It's horsehite if you ask me (excuse the language), but my point was more in general that with FIT in place and you were getting (properly) paid for it, then yeah, every unit you generate from your panels is effectively "self-consumed", but if your on deemed export, then you want to be as high as you can % wise and get "double paid" for every unit :-)

Personally, I am 95-100% every month self-consumption. When I put in the Shed expansion of 2.3Kwp there in August I started to export a little for July, Aug and Sept, but now that we're in the darker months.....I'll be 100% until April I reckon what with the mining for heating etc.

spose

4.7 kw on east/west split with water diverter and no battery. Total self use over the year 82%. 36% of it went in to the water tank

silver_sky

My install/upgrade took place in June but I only have good complete full month data from August. For August and September I'm at 71% and then 67% for October. I've 4.5kWp~, 5kWh battery, Eddi, and an EV. October is lower as I had issues with communication on the Eddi so it has skipped a bit of diversion.

I've also got a Solis inverter like others but on my system at least, their reporting for import and export is way out. I use their generation figures with myenergi data for import and export and pull it together in the homeassistant energy dashboard.

I'm also aiming for 80%+ and I think that would be possible but I'm battling some configuration issues on my system. It's importing & exporting when it shouldn't. Without that I could get pretty high self-use and low import... but it's not to be.

slave1

Two years of PV, am at 88%

DC999

https://www.boards.ie/discussion/comment/119824764#Comment_119824764

Wow, what setup do you have to get to that? Good for us newbies to know what to aim for :)

slave1

No battery (yet), just shift a lot of night time to days (washing machine, dishwasher etc) and EDDI to divert to water, EVs to soak up the higher output days