[TRNSYS-users] FW: PV inverter (Type 48a) to link with hot water tank (Type 534)

[David BRADLEY]

Anas,
   The inverter model (Type48) is waiting for the electrical element at 
the bottom of the tank to tell it that it needs power (i.e. that there 
should be a load on it). However, the electrical element model 
(Type1226) is just a simple on/off device; it turns on when its control 
signal tells it to. The element is waiting for the inverter model and 
the inverter model is waiting for the element.

   There are a many ways that you could fix the issue but which one you 
choose really depends on how you want to operate the system. Here are a 
couple of options:

1. You can put another aquastat watching the bottom of your tank and 
controlling the lower element's on/off signal. The controller (and an 
equation) can then set a value that is either 0 (if the tank is already 
hot enough) or is the maximum power that the element can deliver. This 
value will be passed to the inverter as the load. The inverter will then 
send all of the power that the PV has available to the element (up to 
the inverter's capacity). Connect the inverter's power output to the 
element's capacity input.

2. Often times elements like yours aren't controlled; they just dump 
whatever energy they can from the PV into the tank. In this case you can 
get rid of the inverter and pass the PV output power directly to the 
element's capacity input. In this case leave the element's control 
signal set to zero.

kind regards,
  David


On 06/10/2015 02:05, Anas Majdouli wrote:
>
>
> ------------------------------------------------------------------------
> From: majdouli_anas at hotmail.fr
> To: trnsys-users at lists.onebuilding.org
> Date: Mon, 8 Jun 2015 11:35:19 +0200
> Subject: [TRNSYS-users] PV inverter (Type 48a) to link with hot water 
> tank (Type 534)
>
> Hi TRNsys community,
>
> For my project, I need to simulate a case : DHW production using PV 
> panel electricity output as an input for the auxiliary heating within 
> the tank. I added also an electric aux. heater on the top of the tank 
> to reach the set point temperature (45°C). The TRNsys file is attached 
> to this email.
>
> I am requesting for your help, because the simulation doesn't seem 
> working. I think the problem comes from the inverter. Maybe I haven't 
> linked it correctly to the tank or to the PV panel. Could you help me 
> please ?
>
> Thanks in advance.
>
> Yours Sincerely,
> Anas MAJDOULI
>
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-- 
***************************
David BRADLEY
Principal
Thermal Energy Systems Specialists, LLC
22 North Carroll Street - suite 370
Madison, WI  53703 USA

P:+1.608.274.2577
F:+1.608.278.1475
d.bradley at tess-inc.com

http://www.tess-inc.com
http://www.trnsys.com

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