Author Topic: Off grid system design without batteries  (Read 2833 times)

ASP

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Off grid system design without batteries
« on: April 07, 2015, 04:43:10 PM »
I live in a society with a grid system. However, with regular blackouts, i intend to design and install a PV system without batteries. in essense, i intend to make use of a petrol generator which i already have to power my home at night when the grid power is unavailable while the 3KWp PV array runs most of the basic need during the day when the grid is off or partial use when the grid is on. This possibly will help to reduce monthly energy bills.
The question here is, will the considered design approach be possible and what kind of inverter will be recommended?

NB: During the period when the grid is unavailable, all high energy consuming appliance will be off. However, only a fridge of about 126W and a polystar deep freezer for 288 may be on during the day.
Ps, Nigeria has sufficient solar resource during the day but heat may be an issue as increase in temperature reduces voltage

MJLorton

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Re: Off grid system design without batteries
« Reply #1 on: April 14, 2015, 03:12:39 PM »
The system you are thinking about designing has quite a few challenges. Pure grid tie inverters with no battery backup will shut down when the grid goes down. Using a generator to generate an AC signal to "activate" a grid tie inverter has potential issues. The grid would need to be isolated from the generator and circuits to be powered during an outage.

To simplify things I would get a grid tie inverter / charger with a very small battery bank. Many of these systems will isolate the grid from your circuits you want to power and allow solar to continue working as well as cater for generator input. Victron, Outback and I think SMA have these inverters.
Play, discover, learn and enjoy! (and don't be scared to make mistakes along the way!)

ASP

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Re: Off grid system design without batteries
« Reply #2 on: April 21, 2015, 01:02:00 AM »
Thanks for the simplified approach. I did see some of your videos on youtube and with more emphasis the use of the outback inverter. Will do more research about the product and evaluate the cost with respect to my desired objective.