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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?
Il faut cultiver notre cité-jardin
The Sustainable Plotlands Association

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.