Grid Tied with generator backup - will solar provide any power if grid is down?

[aeajr]

A lot would depend on what your "back-up" power system was intended to do.

f you want to power your house as if nothing happend, that is one thing.

If you are trying to ride through a brief outage and keep a few things running, that is a completely different objective.

If you want it all to happen automatically, that is one thing.

If you don't mind pulling stuff out, running some extension cords and such to get through a 12 hour to a couple of day outage, then you have a different situaion and a much lower up front investment.


So, what is your goal? How completely do you want the house to run? How automatic does it have to be?

You can have a separate panel in the house that is only touched by the generator and/or batteries. Or you can just run inverteres or a generator with extension cords to keep up the fridge, a sump pump, a TV and a couple of lights.

Big $$ difference across all these options. And where and how you tie in the solar PV panels will change too.

First set the goals and the budget. Then define the solution.

[russ]

Just be aware that grid tie may give you 75 to 80% of system rating for output while an battery based system will be closer to 50%.

[GrizzlyGuy]

I've been doing some research to figure out how to do something similar to what you want to do. Take a look at the new Outback Radian grid-interactive inverter:

http://www.solar-electric.com/ourags8wain.html

http://www.outbackpower.com/products/sinewave_inverter/radian/

These units are referred to as grid-interactive. It can be used as a standard grid-tie inverter and offset your utility bill or it can work as an off-grid system. In the event that you lose utility power, the Radian will take over by keeping your house powered. The length of time you will have backup power will depend upon the storage capacity of your battery bank. If you have a generator, the Radian's built-in charger can be used to keep your batteries full. If inclement weather prevents your solar array from charging your batteries, a generator can save the day (and your batteries).

Download the Installation Manual and read the Planning section. Then download the Operating Manual and read the section on Input Modes. Their VFX series inverters have similar functionality for smaller installations.

[russ]

I've been doing some research to figure out how to do something similar to what you want to do. Take a look at the new Outback Radian grid-interactive inverter:

http://www.solar-electric.com/ourags8wain.html

http://www.outbackpower.com/products/sinewave_inverter/radian/

Download the Installation Manual and read the Planning section. Then download the Operating Manual and read the section on Input Modes. Their VFX series inverters have similar functionality for smaller installations.

That is the expensive option - both in equipment and efficiency.

[Mike90250]

I think solar can provide power when grid is down. Many solar power systems with battery backup that can be connected to the utility grid. By the way a grid-tie system refers to a solar power that transfer all of the electrical power generated directly back into the local utility grid and does not have a battery bank.

Welcome. You are welcome here. Your sales .sig is not. Contact user JASON for advertising rates on this board, that is sponsored by http://www.solartown.com/

[billvon]

If someone came back with at "well for $100 you can install a xyzWidgit and then you will have power anytime the sun is shining if the grid is down" then I'd have been interested. Seems I wouldn't be alone in that eh?

In that price range best you're going to do is:

http://www.bestbuy.com/site/APC+-+Back-UPS+XS+BX1000G+1000VA+Tower+UPS/9952013.p;jsessionid=DF83A104A1D745BC141FD5E8754FA6D5.bbolsp-app05-25?id=1218200061225&skuId=9952013

For a system that allows use of solar with a 400-600V grid intertie system you're looking at a $1000 charge controller, a largish battery bank and a standalone inverter. If you have a segmenting combiner AND have wiring access to it you could tap off a lower voltage part of the array. You'd only get a fraction of the array's power but it would be in a lower voltage range that a cheaper charge controller could handle. (Still need batteries and an inverter though.)