EcoRenovator - View Single Post - Solar Back-Up power project

osolemio · 04-12-11, 08:44 AM

Very interesting project! I will be grid connected, but I intend to eventually have a battery backup for several reasons.

One of them being that in case of a blackout, the inverter shuts down and PV production idles. This is where I can continue to use the DC directly to charge a set of batteries. Off these batteries I will run a USB bus, as well as 6, 12 and 24 volt. This enables me to run all these small DC gadgets directly, without using the supplied AC-DC power supplies for each unit - that is, without making solar PV DC into AC, then back into DC. The bus WILL run all the time, but normally it will be solar/grid powered, whereas during a blackout, it would be solar/battery powered.

If the main AC grid has a blackout, the inverter will have to shut down. If not, it would try to run the entire neighborhood electricity use, which is not possible - the inverter would snap instantly! So when a mains AC fault is detected, the inverter will switch to local mode (by a control system I will design - it is not that complicated really). Because of the inverter built-in protection logic, I need an AC current it can sync against. This is where a small battery operated inverter will feed a lead AC into the inverter (instead of the mains AC), to keep it running.

It will still need some further protection circuits, to make sure that demand does not exceed production. Since the battery pack will only supple the small controlling inverter and not the big one, the main AC users cannot be used when there is no sunlight. But the small inverter will keep the solar heat pumps and control running, as well as other essential - but low power - units. Maybe including the TV?

So the two main reasons for me to extend to battery backup are

1) To get the solar PV DC production directly into local DC gadgets, without going DC->AC->DC

and

2) To be able to sustain PV usage in the case of a grid blackout

Would I not feel stupid, if there was a blackout and my PVs cannot be used! That defeats the idea of producing your own electricity!

04-12-11, 08:44 AM	#20
osolemio Hong Kong Join Date: May 2010 Location: Hong Kong Posts: 108 Thanks: 20 Thanked 17 Times in 13 Posts	Very interesting project! I will be grid connected, but I intend to eventually have a battery backup for several reasons. One of them being that in case of a blackout, the inverter shuts down and PV production idles. This is where I can continue to use the DC directly to charge a set of batteries. Off these batteries I will run a USB bus, as well as 6, 12 and 24 volt. This enables me to run all these small DC gadgets directly, without using the supplied AC-DC power supplies for each unit - that is, without making solar PV DC into AC, then back into DC. The bus WILL run all the time, but normally it will be solar/grid powered, whereas during a blackout, it would be solar/battery powered. If the main AC grid has a blackout, the inverter will have to shut down. If not, it would try to run the entire neighborhood electricity use, which is not possible - the inverter would snap instantly! So when a mains AC fault is detected, the inverter will switch to local mode (by a control system I will design - it is not that complicated really). Because of the inverter built-in protection logic, I need an AC current it can sync against. This is where a small battery operated inverter will feed a lead AC into the inverter (instead of the mains AC), to keep it running. It will still need some further protection circuits, to make sure that demand does not exceed production. Since the battery pack will only supple the small controlling inverter and not the big one, the main AC users cannot be used when there is no sunlight. But the small inverter will keep the solar heat pumps and control running, as well as other essential - but low power - units. Maybe including the TV? So the two main reasons for me to extend to battery backup are 1) To get the solar PV DC production directly into local DC gadgets, without going DC->AC->DC and 2) To be able to sustain PV usage in the case of a grid blackout Would I not feel stupid, if there was a blackout and my PVs cannot be used! That defeats the idea of producing your own electricity! __________________ Space heating/cooling and water heating by solar, Annual Geo Solar, drainwater heat recovery, Solar PV (to grid), rainwater recovery and more ... Installing all this in a house from 1980, Copenhagen, Denmark. Living in Hong Kong. Main goal: Developing "Diffuse Light Concentration" technology for solar thermal. Last edited by osolemio; 04-12-11 at 08:49 AM..