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etienne

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Managing PV + battery system
« on: September 20, 2017, 01:43:01 PM »
Hello,
At work, we just started a PV (20 kWp) + Battery (15kWh) system on a building with 4 appartments  that have heatpump heating (well, appartments are only half full yet), and I have to say that it works better than what I expected. Even now mid September, on rainy days, we have enough electricity until like midnight (heating is only needed for sanitary water yet).
A lot of sun doesn't help much because batteries are full around noon, so we start to use extra tips to use PV electricity in excess.
I started the "what to do with PV electricity in excess topics http://forum.arctic-sea-ice.net/index.php/topic,2076.0.html when the conception of the regulation was underway. It seems to work fine.
Since most ways of using excess PV electricity are not so efficient or mean higher energy loss (an overheated boiler has over average heat loss), I decided to stop any not needed electricity use during peak hours (around noon and after 16h) in order to support the local electricity network. The idea is also to have some experiences for future smart meters and regulations that might come with them.
Does any body has experiences in that area, some good tips...
Thanks,
Etienne

etienne

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Re: Managing PV + battery system
« Reply #1 on: September 20, 2017, 06:37:52 PM »
Maybe I should add that the systems installed to use PV power in excess aim to anticipate needs of energy during the time where there is no sun. For example when I overheat sanitary water with PV power, I anticipate the next heating process that might happen when no PV power is available. It's not a waste of energy, the waste comes only from the increasing losses due to higher temperature in the storage tank.

We will have a winter and a summer configuration, because for example during the winter, it could be interesting to heat sanitary water at night when electricity is abundant on the network.

oren

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Re: Managing PV + battery system
« Reply #2 on: September 21, 2017, 10:49:18 PM »
Nice project etienne. I envy you. Nothing like real life experience with these things.

Zythryn

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Re: Managing PV + battery system
« Reply #3 on: September 22, 2017, 02:19:37 AM »
We have a net-zero setup using PV power.  No battery backup yet, but we are planning to have that installed within two months.
One thought would be to charge an electric car when you have a surplus.  Not sure if you have one available during the afternoon, but that will allow for a good chunk of storage.

GeoffBeacon

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Re: Managing PV + battery system
« Reply #4 on: September 22, 2017, 12:50:55 PM »
Etienne

The thinking in your project sounds excellent - I hope the practice is too. Looking forward to results if you monitor the real life situation.

However when you say "appartments are only half full yet" and "charge an electric car" suggests to me that the embodied carbon in building and cars have been ignored.

Do look at Embodied carbon recognised at last.

The Embodied Carbon Task Force of the The Alliance for Sustainable Building Products reported
–Even before a building is occupied, between 30% – 70% of its lifetime carbon emissions have already been accounted for.
–Embodied carbon makes up the largest proportion of the carbon emissions of a building through its lifetime.
Have I go the carbon impact of building new conventional buildings and making new electric cars wrong?

Green thinking with conventional planning can easily fail.

Perhaps your system could work with low rise wooden buildings with bike transport?
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etienne

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Re: Managing PV + battery system
« Reply #5 on: September 22, 2017, 02:18:41 PM »
The building was finished in July. From 4 owners, only one has fully moved. Two owners are still between their old and new appartment, and the 4th owner is looking for a tenant. So I can't give real conclusions yet.

None of the owners/tenant has an electrical car. Probably in the future. Infrastructure will be easy to install, but is not required yet. The problem with EV and PV is that cars are on professional parking lot during the day.

Carbon calculation is not an issue in this project. Our part of the work is energy management, so we don't have a choice regarding the other aspects. It's nice for us when people are ready to buy batteries because with the actual regulations in Luxembourg, it is a "just for fun" investment. I believe that it will change in the future, but not before 2-3 years.

In the "policy and solution/renewable energy" trend is a nice link from ghoti about what could be done anywhere if the network regulator would be ready (its in the Orkney Islands):
https://www.youtube.com/watch?v=VEh7V9_uIqM&feature=youtu.be
but it requires a lot of work on the network regulator side.
Imagine what would happen if the regulator just says he has too much electricity so it is now 20% cheaper. On the building I manage, I can start 12 kW load just on water and buiding heating, but in each appartment is a washmachine, a dryer... It would create a total breakdown of the electrical network.
The PV/battery management system we have allows us to define different loads that can be started with different priorities. So I guess the network regulator could do the same thing, homes could enroll in a project, define what their extra load could be, and the regulator should be able to start them.
In the Orkney project, they solve that problem using the batteries as variable load. I guess that the end users pay always the same price for electricity, so they won't start all the systems together at the minute where it becomes cheaper. Since the utility company knows the load curve of the house, it is able to fill the batteries whenever network and electricity are available and can empty them when there is no load in the house and electricity is expensive. I guess that there are some additional requirements like heating sanitary water at night.
With the renewable/storage revolution, I believe that utility companies won't make so much money on electricity anymore, but on energy management. It's a new business case.

etienne

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Re: Managing PV + battery system
« Reply #6 on: September 27, 2017, 03:10:00 AM »
We are now preparing the concepts for new houses and it's unbelievable how things have change on the last years. It is now possible to find plug and play solutions for PV electricity use optimisation with a heat pump. And is is cheap (like around 500 EUR). Since suppliers have full control of their systems, the plug and play solutions might be more efficient than what can be done with the normal public interface. Configuration is more complicated, but Microsoft has developped the installation wizard concept, I guess this also works here.
With the batteries dropping costs, I wonder if PV optimisation will be an issue in the future. It will be possible to increase the battery size and optimize energy use, not just PV energy use.
Furthermore, heat pumps are also improving quite a lot, and I guess it will soon be interesting to use them for normal houses (not only highly insulated) if you add a pellet stove to bring enough heat for the winter months.

Jim Hunt

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Re: Managing PV + battery system
« Reply #7 on: November 22, 2017, 02:40:12 PM »
Hi Etienne,

I think I just asked my "smart meter" question in the wrong thread!

You may wish to peruse this recent article of mine?

http://www.V2G.co.uk/2017/09/evangelising-v2g-in-south-west-england/

The MyEnergi Eddi/Zappi combination may well be of interest in here? Also we're currently attempting to raise funding for a (hopefully!) novel hybrid PV inverter project. Perhaps we should compare notes at some point?
Reality is merely an illusion, albeit a very persistent one - Albert Einstein

etienne

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Re: Managing PV + battery system
« Reply #8 on: November 22, 2017, 07:00:41 PM »
Hi Jim,

It's an interesting article. The main problem I see right now is that optimisation is tried on a building level, but a wider area should be considered, at least all the users of the 20kV line that supplies them.
Electricity need at night is lower than during the day, which means that I wouldn't use the battery to load the car at night, but to support house consumption in the morning before the sun goes up. On the building I manage, the absolute peaks are in the morning when coffee machines and water heaters are working. Water heater are related to showers and coffee machines to breakfast. There is also a peak in the evening, but wider and lower (probably higher total consumption, but during more time). Maybe we should have had a bigger warm water storage.
The second point is that the general load curve is higher during the day, so on a global level, PV related batteries could only be loaded when global supply is insured without CO2.
I wonder how smart grid will be able to manage a fair sharing of the incomes related to discharging batteries in the network when electricity demand is high. Same question about who will be able to load his battery with cheap electricity when supply is higher than demand.

Regarding MyEnergi Eddi/Zappi, I have to read more about it. I can't give you an answer yet.

Etienne

Jim Hunt

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Re: Managing PV + battery system
« Reply #9 on: November 22, 2017, 09:09:41 PM »
A wider area should be considered, at least all the users of the 20kV line that supplies them.

It's funny you should mention that! Agreed, except that here in the UK it's 11 kV.

Electricity need at night is lower than during the day, which means that I wouldn't use the battery to load the car at night, but to support house consumption in the morning before the sun goes up. On the building I manage, the absolute peaks are in the morning when coffee machines and water heaters are working. Water heater are related to showers and coffee machines to breakfast. There is also a peak in the evening, but wider and lower (probably higher total consumption, but during more time). Maybe we should have had a bigger warm water storage.

The MyEnergi system certainly relies on heating water when all other attempts at self consumption fail.
 
The second point is that the general load curve is higher during the day, so on a global level, PV related batteries could only be loaded when global supply is insured without CO2.

Not that it's a lot of use to you in Luxembourg, but you might be interested in our open source UK grid carbon intensity app?

http://www.V2G.co.uk/projects/national-grid-carbon-intensity-api/

Today's graph is below.

I wonder how smart grid will be able to manage a fair sharing of the incomes related to discharging batteries in the network when electricity demand is high. Same question about who will be able to load his battery with cheap electricity when supply is higher than demand.

The $64,000 question! The conventional answer is a fully functional "local energy market", but we're a million miles away from such a thing in the UK.
« Last Edit: November 23, 2017, 12:40:38 AM by Jim Hunt »
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etienne

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Re: Managing PV + battery system
« Reply #10 on: November 22, 2017, 10:52:52 PM »
When I check the datas of my Smappee, I see that I use between 6 and 12 kWh per day.  I guess that the highest power usage was around 10kW, but we didn't pay attention at limiting total power.
This means that with a 5 kWh battery, I really could cut all the peaks of my consumption. I guess this might be a solution for the future :  a battery that fills itself when power is available, and makes sure that I never take more than 4 kW from the network.

sidd

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Re: Managing PV + battery system
« Reply #11 on: November 23, 2017, 12:27:26 AM »
" a battery that fills itself when power is available, and makes sure that I never take more than 4 kW from the network."

Called "peak shaving"  and being used in industrial and commercial settings. A lot of is is thermal store (supercool freezers or make ice when power is cheap) but some is battery based. This is important for thos (usually) large electric customers whose rates are partially basd on peak load.

sidd

Jim Hunt

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Re: Managing PV + battery system
« Reply #12 on: November 23, 2017, 10:15:21 AM »
For the benefit of Neven (and anybody else who might be interested) this is what my SMETS 1 spec smart meter looks like. Hopefully the SMETS 2 devices due RSN will actually possess some smarts!

The communications module is at the top. WAN is GPRS, when it can get a signal. HAN is ZigBee, which communicates with the mini tablet inside the house, amongst other things.

Thanks in part to the Great British Chancellor of the Exchequer we're currently seeking expressions of interest from anybody in Europe with a suitably smart meter who might be interested in beta testing some novel electric vehicle charging equipment in a few months time.
Reality is merely an illusion, albeit a very persistent one - Albert Einstein

etienne

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Re: Managing PV + battery system
« Reply #13 on: November 23, 2017, 10:45:40 PM »
" a battery that fills itself when power is available, and makes sure that I never take more than 4 kW from the network."

Called "peak shaving"  and being used in industrial and commercial settings. A lot of is is thermal store (supercool freezers or make ice when power is cheap) but some is battery based. This is important for thos (usually) large electric customers whose rates are partially basd on peak load.

sidd

Peak shaving as described is much easier to manage in the context of industrial and commercial settings because they usually have an infrastructure managing system and have a wider choice of load to start and stop.
At home, my peak is in the evening (lights on) when the chicken is in the oven and the potatoes + the vegetables in two different pans. Even if I would stop my refrigerator and would make sure that no laundry appliance works at the same time, this wouldn't solve my problem.
To be very honnest, this is not a problem right now, but next year in Luxembourg we will have a proof of concept on a residential building with self consumption of PV electricity where the network costs will be based on the highest peak of the year. In the 2017 context, self consumed eletricity has the same network cost than bought electricity because the network was available to transport it. The building has batteries with an SMA home manager, so it would be nice to use it for peak shaving. We asked for it and got more specific questions about our needs, so maybe they will offer the functionnality sometimes in the future.

Neven

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Re: Managing PV + battery system
« Reply #14 on: November 24, 2017, 12:10:31 AM »
Jim, does 'intimate communications hub' mean you have to report the numbers without any clothes on via webcam?  ;)

Sorry for all the bad jokes.

I'll go and see what kind of a meter my meter actually is.
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Jim Hunt

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Re: Managing PV + battery system
« Reply #15 on: November 24, 2017, 09:27:39 AM »
Good morning Neven. Actually I'm quite partial to "bad jokes" myself. In fact I have one of my very own to share with you!

Perhaps you and any other renewable energy enthusiasts in the house might wish to bookmark the Twitter thread that I just recommended to Professor Richard Betts of the UK Met Office?

https://twitter.com/jim_hunt/status/933970006106411009
« Last Edit: November 24, 2017, 11:02:04 AM by Jim Hunt »
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etienne

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Re: Managing PV + battery system
« Reply #16 on: November 25, 2017, 03:54:10 PM »
When I look at my consumption graph (5 minutes average), shaving peaks above 1,5 kW would require almost no battery power, but it would require a high power inverter and a fast discharging batteries.

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Re: Managing PV + battery system
« Reply #17 on: November 25, 2017, 05:19:36 PM »
When I look at my consumption graph (5 minutes average), shaving peaks above 1,5 kW would require almost no battery power, but it would require a high power inverter and a fast discharging batteries.
That looks to be readily available. The Tesla Powerwall provides 5kW steady output and 7kW peak output. It has the inverter built in. I would be surprised if similar wasn't also available from Sonnen and other battery providers.

sidd

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Re: Managing PV + battery system
« Reply #18 on: November 25, 2017, 09:26:54 PM »
"When I look at my consumption graph (5 minutes average), shaving peaks above 1,5 kW would require almost no battery power, but it would require a high power inverter and a fast discharging batteries."

Could you integrate the peaks above 1.5kkW and estimate averages/medians/peak energy requirements in KwH as well ? I ask because this might be an application for a capacitor bank coupled to batteries.

sidd

Jim Hunt

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Re: Managing PV + battery system
« Reply #19 on: November 25, 2017, 10:52:03 PM »
The Tesla Powerwall provides 5kW steady output and 7kW peak output. It has the inverter built in. I would be surprised if similar wasn't also available from Sonnen and other battery providers.

Similar devices are indeed available from a variety of other battery providers. Here are just a few:

http://www.v2g.co.uk/2015/06/is-distributed-energy-storage-on-ofgems-roadmap/

Scroll to the bottom to see them. I'm late to this party I'm afraid, so if I may enquire:

Etienne - Do you have high voltage batteries like the Powerwall (et al!)
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etienne

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Re: Managing PV + battery system
« Reply #20 on: November 26, 2017, 12:47:02 PM »

Could you integrate the peaks above 1.5kkW and estimate averages/medians/peak energy requirements in KwH as well ? I ask because this might be an application for a capacitor bank coupled to batteries.

sidd

Yes, but not today. Maybe middle of next week.

Etienne

etienne

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Re: Managing PV + battery system
« Reply #21 on: November 26, 2017, 10:12:58 PM »
Well, here are some first results.

Average power usage is around 400 W

I have a scenario where I load batteries at night (24h time frame):

I need 1.9 kWh to shave peaks above 1.5 kW, and 0.9 kWh to shave above 2 kW.
If I remove the day where my wife used the dryer (clothes), the values are 1.2 kWh and 0.6 kWh.

There is also a 4 hours scenario (close to a V2G configuration)

I need 1.1 kWh to stay under 1.5 kW and 0.6 kWh to stay under 2kW.
Here again, if I remove the dryer's day, it is 0.35 kWh and 0.7 kWh.

Here, I still need to check if power usage goes down enough to allow battery charging before the next peak.


Of course, the needed power is quite important, like 7 kW (Smappee also shows real time values, but doesn't keep them).

sidd

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Re: Managing PV + battery system
« Reply #22 on: November 27, 2017, 01:30:39 AM »
Capacitors capable of holding kilowatthours are monstrous, gotto go with battery. 2wH is fairly small for batteries. That said, capacitors can help with motor start loads, but handle with care, you may get overheating of motor coils if you do it wrong.

sidd

TerryM

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Re: Managing PV + battery system
« Reply #23 on: November 27, 2017, 02:17:30 PM »
Quick start / hard start kits on AC/Heat Pumps help with start loads, but resistant heating for clothes driers can be a problem. In low humidity environments disconnecting the heaters and siting the drier outside works well. In winter venting a conventional dryer's heat back through the building cuts heater usage.
Caution, may not work efficiently away from desert regions. 8)


Terry

etienne

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Re: Managing PV + battery system
« Reply #24 on: November 27, 2017, 09:04:33 PM »
Hello,

Here are the last values.

The median value of my electrical consumption is 290 W, much under the average that was 390 W.
This is not a surprise because peaks are very thin.

The 4 hours scenario works, it means that I have always enough time with low power to reload the battery within the 4 hours following a peak, even if I want to stay under 1500 W of maximum power. That's good news for the V2G concept.

Best regards,

Etienne

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Re: Managing PV + battery system
« Reply #25 on: November 27, 2017, 09:46:14 PM »
resistant heating for clothes driers can be a problem. In low humidity environments disconnecting the heaters and siting the drier outside works well. In winter venting a conventional dryer's heat back through the building cuts heater usage.
Caution, may not work efficiently away from desert regions. 8)


Terry
If one is seriously considering powering one's house with a PV + battery system, the very first thing to do is get rid of a clothes dryer. Clothes dry perfectly well hanging up, inside or out.

etienne

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Re: Managing PV + battery system
« Reply #26 on: November 27, 2017, 09:50:41 PM »
Hello,

Here is my 4 hours scenario using the data of the day with the highest requirements. Battery need is 1,1 kWh.

I only use the dryer 4 to 5 times a year, so I think it's no use to buy a new one.

Best regards,

Etienne

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Re: Managing PV + battery system
« Reply #27 on: November 29, 2017, 10:12:27 PM »
resistant heating for clothes driers can be a problem. In low humidity environments disconnecting the heaters and siting the drier outside works well. In winter venting a conventional dryer's heat back through the building cuts heater usage.
Caution, may not work efficiently away from desert regions. 8)


Terry
If one is seriously considering powering one's house with a PV + battery system, the very first thing to do is get rid of a clothes dryer. Clothes dry perfectly well hanging up, inside or out.
Undoubtedly true.
I was simply listing a few of the things I used when living in the Mojave desert. I think the solar preheater for the hot water system, and shunting much of my A/C's heat load into my swimming pool were probably the most successful ways that I avoided a high energy bill.
Living in a more forgiving climate presents it's own problems.
Terry