Pv + micro-inverters = heat DHW ...

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chris34
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Pv + micro-inverters = heat DHW ...




by chris34 » 16/07/18, 15:48

Hello,
Yes ..... I know, it is not very standard to heat water with PV, but, I am in isolated site, with some panels (1,5 Kwc), and I have a very small cumulus (30 L). In short, currently I gently warm my cumulus with my prod. from panels (via batterries, and via programmable switch, so that during the day). Precision, in order to stretch the heating time, I converted, before the cumulus the 230 V into 115 V, which allows me to draw 4 times less power in an instant T. Well, all this works really well, but today, I would like to disconnect the heating cumulus batterries, putting for example 2 PV connected to micro-inverters themselves connected directly to the transformer. 230 / 115 V.
My question: is it better to do
A) PV + micro inverters 230 V + transformer 230 / 115 V + cumulus ECS
Ou
B) PV + micro inverters 115 V + cumulus ECS

Easy, no ???? : Lol:

Thanks in advance !!!! : Mrgreen:
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Gaston
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Re: Pv + micro-inverters = heat DHW ...




by Gaston » 16/07/18, 18:38

Please note, it is not possible to connect "standard" micro-inverters to a resistor without battery or network.
Indeed, they do not have the possibility to adjust their output power when the input power decreases.
The result will be very disappointing.

You should go through this subject.

For example this model unearthed by xboxman4 adjusts its output voltage between 10 and 240V to vary the power supplied to the water heater.
Last edited by Gaston the 16 / 07 / 18, 18: 50, 1 edited once.
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Re: Pv + micro-inverters = heat DHW ...




by izentrop » 16/07/18, 18:39

Hello,
Go through a micro-inverter and a transformer to power a resistance is a lot of unnecessary losses. The best is to adapt the resistance to the PVs. What are the characteristics of the PV and the ball? is it a steatite resistance?

For the ball, it is enough to know the power in 230 V and for the PVs, nominal voltage and power?

Gaston, is it standard M215? https://enphase.com/fr-fr/produits/micro-onduleurs
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Gaston
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Re: Pv + micro-inverters = heat DHW ...




by Gaston » 16/07/18, 18:53

izentrop wrote:Gaston, is it standard M215? https://enphase.com/fr-fr/produits/micro-onduleurs
From what I see, it's an inverter for injection, so it will not work off-grid.
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thibr
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Re: Pv + micro-inverters = heat DHW ...




by thibr » 16/07/18, 22:08

with a PVrouter it must be possible to do things if the inverter is sufficiently "clean" (pure sine wave) to allow synchronization of the miro-inverter
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