My 9kWp Photovoltaik Anlage

[Gambatte 897]

Just for fun, I share some recent data from my own Photovoltaik Anlage.

Interesting measured quantities are the following:

 

production

consumption

own use

bought from the grid

sold to the grid

 

Fig 1: each of the above, vs time of the day, vs day of the year, all quantities in W

[Gambatte 897]

 

Fig.2: Next I separate the days into 3 sets: summer, autumn and spring, and winter. "Summer" is defined as the 25% of the overall days with most production, "Winter" as the 25% days with least production, "autumn and spring" no need to explain.

Then I average the daily production, so a set of 24hr charts, for each season. 

[Gambatte 897]

Fig.3: How much would a battery, of whatever size, reduce my yearly grid reliance? Here we go...

Calculated like this: sum over the 365 days of the following MIN(AkkuCapacity, Grid reliance, Feed-in).

Anything more than 4kWh would be useless. The smallest Akku I could get a quote for was 10kWh.

Of course this does not look at the cost of the Akku.

 

 

 

[Gambatte 897]

Some observations from the data:

Consumption is the same in summer and winter. So having the lights on consumes very little electricity.

Difference in production between summer and winter is very huge. Both for peak production and day duration.

The 24hr charts shows my wife making early morning tea at 500, breakfast at 630, lunch at 1230, dinner at 1900, evening cup of tea at 2130.

Evening cup of tea moves to a later time in the summer, maybe because of long days?

Own production covers most of summer daytime electricity (excluding preparing evening meal).

Night consumption at 140W is much higher than I would have guessed.

 

Comments? Questions? Anyting...?

[YoRambo 117]

Very Interesting Gambatte...How big is the area of your PV Anlage?

We are also looking for one , keep us posted with these stats .Thanks

[Gambatte 897]

The system is overall 29 modules, 315Wp each, so 9135Wp, and it's split almost exactly 50/50 East/West.

East/West is of course less good for overall production, but better for using the electricity it produces because the day-peak is more distributed in the morning and late afternoon, which is when you need it most. Having said that, I think if you could chose the roof orientation (most folks can't, and we couldn't although we built the house) South would be overall better.

[fraufruit 41,944]

17 minutes ago, Gambatte said:

The 24hr charts shows my wife making early morning tea at 500, breakfast at 630, lunch at 1230, dinner at 1900, evening cup of tea at 2130.

My, what a good wife you have.

[Gambatte 897]

4 minutes ago, fraufruit said:

My, what a good wife you have.

[Gambatte 897]

Fig.4: Here 2021 data on a monthly basis.

If you think photovoltaik helps a heat pump look at this chart and think again...

 

[mtbiking 1,883]

Very good analysis! Thanks! I'm going to accept an offer I currently have on the table for the installation of a PV. There were some points in the contract which I needed clarified or modified, but now we reached an agreement. There's one last company coming this Wednesday from which I expect another offer, but I've had some rounds now and barring a surprise the decision is taken.

 

Core data, which I computed on my own, they just had to implement the system:

-> West-East orientation, Spz. Jahresertrag 968 kWh/kWp

-> almost all available roof used: 35 modules, 400 W each ->14 kWp

-> Battery 7.7 kWh

-> theoretical PV Production 13550 kWh/year

 

I'm calculating with a consumption of 8000 kWh/year - house and electrical car

 

In my computations the amortization comes after 11 years. My computations also show that the batttery doesn't make economic sense. I still want one because 1) we can easily afford it 2) I'm a bit of a prepper -> I also hoarded around 14 cubic meters of firewood in preparation for this winter, and candles, and food.. mostly everything except toilet paper.

[kiplette 8,676]

9 minutes ago, mtbiking said:

I also hoarded around 14 cubic meters wood in preparation for this winter

 

That's impressive.

[mtbiking 1,883]

7 minutes ago, kiplette said:

 

That's impressive.

 

thanks, I guess . we are lucky to have the storage place, even though I had to get creative for the last 6 m3 or so. 

[Dembo 495]

2 hours ago, Gambatte said:

Fig.4: Here 2021 data on a monthly basis.

If you think photovoltaik helps a heat pump look at this chart and think again...

 

 

Very interesting. I assume this one actually is the calendar months and not your 25% best days calculation? I was surprised from the first set how poor autumn/spring was but here spring at least seems pretty good.

On TV the other day was something about a family that had invested in a hydrogen storage system for storing the surplus solar from summer and using it in winter. It meant having a load of hydrogen tanks and a shed's worth of equipment in the garden and it would only provide about 25% of what they needed over the winter and I can't imagine it was cheap. 

[murphaph 9,650]

I think the roof orientation and overall system size makes a massive difference as to whether or not a PV system can assist a heat pump in a meaningful way, or not. You get more power from a larger system, obvious enough, so if your PV system is big enough, it will be able to make a meaningful contribution even in winter (not every single day of course, clear days much more than overcast days which will remain fairly poor) but with most "normal houses" you're going to be limited as to how much space you have for panels so "system size" is less relevant. That's where the roof orientation and pitch makes a much bigger difference. An east-west orientation produces less power during the whole year than a pure south facing roof but it can mean an increase in Eigenverbrauch (but this really depends on your lifestyle. If you are a pair of home office people and are typically eating your warm meals in the afternoon and your cold meals in the evening, as we do, you and you are able to run your heavy appliances like the washing machine, dishwasher and heat pump in the afternoon sun, then you can use a lot more energy from a south facing roof than a couple that work 9-5 outside the home and are forced to feed most of that energy into the grid). If you have a straight south facing roof then the pitch angle and horizontal shading will then be major factors  in deciding if a heat pump can be meaningfully assisted by the PV in winter. If you have a steep roof of 45° or more and no shading on the horizon, you are in a very different position to someone with an east-west orientation where virtually no power is being produced, even on a clear winter's day at midday (the sun is low and the angle of incidence is very shallow). Such a roof will capture significantly more energy as the suns irradiation will be hitting it at close to 90°. I would say nobody should assume that a PV system is going to be of much use in conjunction with a heat pump BUT I would caution against blanket statements that it cannot also. It is so specific to the installation that there's no way to give general advice IMO. I believe on completely overcast days the best roof is a flat one as the little UV light that comes through the clouds is completely diffuse and comes "straight down". A mix of pitched and flat roofs seems to make sense to me, if you have a suitable flat roof available.

[murphaph 9,650]

8 minutes ago, Dembo said:

 

Very interesting. I assume this one actually is the calendar months and not your 25% best days calculation? I was surprised from the first set how poor autumn/spring was but here spring at least seems pretty good.

On TV the other day was something about a family that had invested in a hydrogen storage system for storing the surplus solar from summer and using it in winter. It meant having a load of hydrogen tanks and a shed's worth of equipment in the garden and it would only provide about 25% of what they needed over the winter and I can't imagine it was cheap. 

That's the kind of thing best left to bigger operators IMO. There's a network already existing that PV can feed in to in summer and I suspect larger systems are much more efficient than extremely decentralised ones. The hydrogen can then be used in hydrogen based power stations to generate electricity in winter. Each to their own but I don't know if I'd feel entirely comfortable with hydrogen storage in or near my house.

[vivanco 173]

2 hours ago, Gambatte said:

Fig.4: Here 2021 data on a monthly basis.

If you think photovoltaik helps a heat pump look at this chart and think again...

 

In above curve, Does self use + grid reliance + consumption = energy that you used?? 

[Gambatte 897]

36 minutes ago, murphaph said:

I think the roof orientation and overall system size makes a massive difference as to whether or not a PV system can assist a heat pump in a meaningful way, or not. 

Can you please attach a number to the word "massive"? And evidence please.

 

Plus, our E W roof is fully covered with modules. If we had a S side we would also have a N one, meaning the possible number of modules is halved, so at best a 4.5kWp system. Keep the garden free please, that's where I grow the strawby and veggies. 

 

Oh, and on a sunny Xmas day (after all every Xmas is sunny here in Germany) the optimum S modules produce zero outside 9am-3pm.

[Gambatte 897]

19 minutes ago, murphaph said:

Such a roof will capture significantly more energy as the 

How much is significantly?

[Gambatte 897]

14 minutes ago, vivanco said:

In above curve, Does self use + grid reliance + consumption = energy that you used?? 

Good question.

No, rather this:

selfuse + gridereliance = consumption 

 

Of course could well be that I made mistake in my python script. If so, please:

1) my apologies, and

2) please inform me and i will amend ASAP 

 

 

[Gambatte 897]

1 hour ago, mtbiking said:

My computations also show that the batttery doesn't make economic sense. I still want one 

You know my conclusion on the financial aspect of a battery and I won't repeat it. Still friends.

But one more point point against battery, not yet discussed here, is the environmental one. Like everything, they need to be manufactured transported disposed etc etc. This of course has its own impact on the environment.

 

If I buy a new car and never use, my purchase still impacts the environment.