home PV solar

[Darell]

Originally Posted by idleprocess

From what I was reading on Xantrex's site, I was under the impression that their grid-tie inverter will detect a blackout and provide local AC power while isolating itself from the grind until utility power is restored...

If this is true, it is news to me... and it is about time!

[TedTheLed]

D. where have you been? My years-old Trace is designed to 'send through' outside power when available, as from a generator, and immediately switches back to battery when the gen (or grid) is shut off..it also sends excess power to the batteries through the charger..

McG. there are freezers designed to be used with generators (or panels, or anything) for short periods of time; they contain some sort of salt I believe, and retain the cold for many hours ie. overnight. Ideal for day charging from panels..

[theforester]

I was under the impression that this type of inverter already existed as well. I contacted an installer in the Cleveland area a few years ago and he refered to this as a "grid-interactive" system as opposed to a grid-tie. However, it's entirely possible that I misunderstood him.

[McGizmo]

Idle,
That sure sounds like the right ticket but I guess I'll have to wait and see what I have coming and what, if any, options I have open to me.

Ted,
I already have the freezer so it is likely a moot point. Those freezers do sound cool though (literally). I have been accumulating some data on it with a Killawatt that of course reset itself or lost the data with the power outage yesterday. Duh! It's a full size commercial unit (front loading) but I think it is reasonably efficient and I don't think it unreasonable to think that the PV array with a modest bank of battery(s) couldn't keep it operational during a blackout.

[Darell]

Well, I'd love to be proved wrong on this, guys. The thing is... many of my customers (including me!) would love this feature, and I've not been able to offer it. Maybe the tech exists, but it isn't legal in CA? I'm familiar with hundreds of PV installations, and I know of NONE here in CA that can accomplish what I want.

Wouldn't be the first time that I end up in the dark though!

[Brock]

The system I have has a relatively small battery bank (compared to an off grid system). Our system can power loads on the "load" side of the inverter with or without the grid present. If the grid is available and the panels are producing more power than the load side is consuming it will push the excess power out to the grid. If your consuming say 4000w and the solar array is 2000w the inverter just takes 2000w from the grid and adds it to the 2000w from the array to supply the 4000w load.

Of course the type of inverter I have is more expensive then a straight grid tie inverter and is less efficient since it also has to maintain the batteries. Also in the long run you have to replace the batteries which adds to the cost and complexity of the system. You also ahve to rewire certain loads to a sub panel fed by the inverter, which also adds cost.

In the end there are two ways to go if you already have a grid tied inverter like yours. You can buy a small genset (I recommend a Honda 2000i) and just power the loads while the grid is down. The second option is to use another sine wave inverter to trick the grid tie in to thinking the grid is up and powers up and sends power to your house. This is a lot more complicated and more expensive then a simple genset. But if you do have regular outage's it might be the way to go.

If you want to follow a thread on the wind & sun forum of how that acutally works look here

Again I wouldn't suggest going this route unless you’re really familiar with how grid tie inverters really behave. A simple small generator is a lot more straight forward.

[luckybucket]

How do pv panels stand up to hail? I live in Kansas and have been convincing my wife we need solar arrays at our next house which will be bought in a year or so, but I have not found any information about the surface protection of pv panels at the many websites I have visited. Also do the battery chargers come in flavors to feed other battery types like LIFEPO4? I know they are expensive but I believe they may last longer than SLA and they are more environmentally friendly. I'm still learning about batteries so correct me if I'm wrong. The good thing is I won't need a lot of batteries if I go that route because I will be following Darell's advice and cutting consumption to a minimum as first priority.

[usLEDsupply]

The second option is to use another sine wave inverter to trick the grid tie in to thinking the grid is up and powers up and sends power to your house. This is a lot more complicated and more expensive then a simple genset. But if you do have regular outage's it might be the way to go.

i don't know if it would be possible or not but couldn't it be as simple as getting a large UPS and installing it between your inverter and the house and direct wiring it to your battery bank so if your main inverter goes out it would take over and run until your batteries were dead

(yes you would loose some efficiency and it may not be able to provide enough power to charge the batteries but i would think there would be ways around that by somehow tying the solar panels to the batteries if they aren't already)

if worried about the UPS charging the batteries you could just install a small 120v AC relay between the inverter and UPS so as long as there is power coming from the inverter it will disconnect the batteries form the UPS. or if worried about system efficiency you could use another relay after the inverter to bypass the UPS altogether as long as there was there was power coming from the inverter, so if the grid went down it would reconnect the UPS and Battery Bank to provide near instant backup power with little extra cost

that would get around any laws as there is no law that says you can't use a UPS in your house

[Darell]

Originally Posted by luckybucket

How do pv panels stand up to hail? I live in Kansas and have been convincing my wife we need solar arrays at our next house which will be bought in a year or so, but I have not found any information about the surface protection of pv panels at the many websites I have visited.]

Your best bet is to find a local installer and ask them. There are panels made that have no glass. The top skin is an amazingly durable plastic - much like what car body panels are made of these days, but clear. You can beat it with a hammer, throw them on the concrete, jump up and down on them. I have two of these panels that I take for show-and-tell when I do school visits. You just can't hurt them. If the hail damage thing is the only thing holding you back, then you're good to go.