Adding Solar panels to a grid down, back-up power system.

jack
New Member

Posts: 2

Adding Solar panels to a grid down, back-up power system. Apr 29, 2014 12:27:56 GMT -8

Post by jack on Apr 29, 2014 12:27:56 GMT -8

Hello,
I have put together the parts for a back-up power system designed for having power available to
rechargeable devices and low power electrical devices.
The components of the system are:
Two Optima D31M batteries(12v 75 Ah)
CTEK Multius 7002 charger
Samlex 600 watt sine wave inverter(thinking about the 1000 watt version)
Go Power Electric auto transfer switch

What I'm thinking of adding is two of the Renogy 250watt 24volt panels and
the Renogy 40amp MPPT Charge Controller.

The panels would be tucked away until needed(grid down) and then pulled out
and leaned up to begin the charging.
One of the techs at Renogy called me to talk about doing this and said the controller
could handle the switch from 24v to 12v output, but would be pushing the upper
limits(amps wise) of the MPPT with two of the 250watt panels. The only reason I was
considering two was to get the batteries recharged faster( since this would be a manual
placement and sun adjustment set-up), especially if I add another D31M to the mix.
Any thoughts on my proposed set-up?
Thanks,
Jack

jack New Member Posts: 2	Adding Solar panels to a grid down, back-up power system. Apr 30, 2014 9:55:45 GMT -8 Select Post Deselect Post Link to Post Member Give Gift Back to Top Post by jack on Apr 30, 2014 9:55:45 GMT -8 Anybody from Renogy tech willing to respond to this? I'm trying to spend money on your products, but want to make sure I'm doing it right. Jack

jsb2000
Solar Addict

Posts: 169

Adding Solar panels to a grid down, back-up power system. May 5, 2014 13:04:19 GMT -8 Admin likes this

Post by jsb2000 on May 5, 2014 13:04:19 GMT -8

I think you also need to factor in how long you expect to be without grid power. If you expect to be in a grid down situation for an extended period of time then extra batteries and panels become critical. If you only expect to be down for a short time then they aren't as critical.

You also should factor in wear and tear on the batteries (IE how deeply you expect to discharge them). It's all a balancing act: Spending more on high power panels/controllers might save you from replacing your batteries as often due to deep discharges, but you're still going to be replacing those batteries in around 5 years or so...even if you never use them!

Personally, I went for Renogy's 100 watt starter kit, a 12V 80Ah battery, and a 400 watt inverter to get started. Then I changed over to LED strip lights in order to reduce the power requirement. So far, I'm using this for office lighting, recharging laptops/cell phones, and running low power equipment (like routers, modems, etc.). It also acts as an emergency source of power for a sump pump in case we get flooding and the power goes out. Even with this minimal setup, all it takes is one good day of sun to keep the battery in its happy zone.

Not trying to deprive Renogy of a sale...but the question I'd ask myself is...do I really need 500 watts of juice to do what I want to do?

Adding Solar panels to a grid down, back-up power system.

Post by jack on Apr 29, 2014 12:27:56 GMT -8

Post by jack on Apr 30, 2014 9:55:45 GMT -8

Post by jsb2000 on May 5, 2014 13:04:19 GMT -8