Consumer Homes.

Question:

> Hello again! > I’ve signed my PV system contract, and paid my deposit.  Is it ethical > to share the name of the company here?  

Why not? Should I wait until I have > learned whether I had a good experience?

You can post your experiences on the fly, and if a decision you are making is questionable, I’m sure someone will comment on it.  Maybe even when it isn’t questionable! > Is there a renewable energy equivalent to the misc.comsumers newsgroup?

Just this NG that you in plus "alt.energy.homepower" and "alt.solar.photovoltaic" principally. > Anyway, my system configuration will be grid-tie only for now.  I will > be installing 26 or 27 BP3160 panels, and two inverters.  The reason > for the ambiguity will become clear below.

I think you will be happier this way, I am. > As you may recall, I was nervous about whether the SunnyBoy Island from > SMA would ever be available in California.  William Smith reinforced my > concerns.  The Island would be a great device to have if you own SMA > inverters, since the backup will plug straight into these high-voltage > devices.  

It appears it will be per conversations I’ve had with them recently, since that is an interest of mine since I have their inverters now. > Other manufacturers’ battery-based inverters, on the other hand, > connect straight to the PV panels.  The problem, as I understand > it, is that the grid-tie inverters like high voltage and low current; > the battery inverters like the opposite.

It is my understanding that the advantage is not due to any specific aspect of the grid tie preferring high voltage, but more to the point the high voltage is a lot cheaper to wire and it is more efficient from the point of line loss getting from the panels to the inverter. In my case I would have had to mount low voltage inverters in 4 widely separated places and then run the AC to the service panel for the required disconnect,  It just didn’t work well for me!  By the way I only needed 10 AWG solid copper wire with 600 V insulation for the 100′ plus DC home runs to the 2 (2 pole) DC disconnect switches next to my 4 Sunny Boy inverters.  Much cheaper than the 48 VDC wire (4 AWG) which still had to be less than 70′ long (It takes 40′ to just get down off the roof to the back of the house). > Given that I don’t know what to expect, I’ve decided to invest in some > extra wiring.  All of the DC home runs from my PV modules will come > down to a combiner box.  The taps from the combiner box will initially > be wired in series for grid-tie inverters, providing high voltage.  If, > in the future, I need low voltage for a battery backup, the modules > themselves will not need to be rewired.  We will just add taps from the > combiner box that tie the PV modules together in parallel instead of in > series.  This extra pre-wiring is only costing me $700.

I am considering maybe using a small motor generator (5 to 7.5 kWh DC) feeding a small capacity high voltage battery pack with that in turn using the Sunny Island system to power my house in an off grid situation.  I know it will be much easier to go from the 2 DC system than to attempt synchronizing an AC motor generator with the inverter AC.  I figure the motor generator is a lot cheaper solution than solar is for the % of time it would be needed in emergencies even at night. – Hide quoted text — Show quoted text -> I’ll probably buy a third inverter, if I ever install the battery > backup.  The nice thing about this third inverter is that it would not > need to be an expensive one.  Since it would only operate off-grid, it > would not have to provide utility-grade, true sine-wave AC power. > I thought that I would be eliminating my SMA vs. non-SMA inverter > choice issue by making these decisions.  Nope!  I initially thought to > buy two SunnyBoy 2500 inverters, and to run two strings of 13 panels > each (26 total).  At signing time, the contractor offered me another > option.  He thought that I might want to consider the Xantrex GT 3.0 > inverters instead.  His reasons: > 1. Available for the same price as the Sunny Boy 2500 > 2. Slightly higher efficiency than the SunnyBoy 2500 (0.6% — Is this > even real?  Is it worth quibbling about?)

Not worth quibbling, my sunny boys are running as much as 10.125 kW occasionally and that is better than the CEC #s. > 3. Monitoring the Xantrex units is easier because they have 10BaseT > connectors (and I have a router), whereas SunnyBoy uses old-fashioned > RS232, and requires a dedicated modem for each inverter

I do not understand you here, my 4 Sunny Boy 2500s do NOT have the display units and are interconnected with a RS485 daisy chain that then runs inside the house to my Sunny Boy Control. I do use a single built in RS232 drop from that Sunny Boy Control to attach it to my PC, because it came with a nice PC Program for monitoring the entire system and it even links to the internet if you want it to. ) > 4. 3000 W capacity, allowing me to enlarge the PV array later (might be > important if I ever add batteries, as I’ve recently learned to expect > 10% to 20% efficiency loss in a battery system *even during those times > when the grid is up*???)

Yep, so why mess with the batteries at all? > Here’s the catch.  The Xantrex GT 3.0 inverters have two internal legs > of 1500 W each.  Each leg needs a minimum of nine panels in series to > boot them up.  So the contractor suggested to me that I run three > strings of nine module each, for a total of 27.  I will buy one extra > module in this configuration.

Again, why mess with the Xantrex and batteries at all?  I know that around here the local dealers all seem to prefer the SMA equipment.  The Sunny Boys have been good service for me for 1.5 years now and a neighbor replaced his Xantrex with Sunny Boys 2 years ago, but I do have to say, I understand the problems he had, have been corrected. > So, even though I sometimes feel like I’m running around in circles, > I’ll ask my question.  Does anyone have an opinion about the Xantrex GT > 3.0?  How does it compare to the SunnyBoy 2500?  As always, my biggest > concern is reliability.  But feel free to share anything you know that > would cause you to recommend one unit over another. > Thanks once again! > — > Rainforest laid low. > "Wake up and smell the ozone," > Says man with chainsaw. > John J. Ladasky Jr., Ph.D.

– Jim Baber 1350 W Mesa Ave. Fresno CA, 93711 (559) 435-9068 (559) 905-2204 (A no charge Verizon IN cellphone to other Verizon IN accounts) See our 10kW grid tied solar system at "www.baber.org"

Response:

Hello again! I’ve signed my PV system contract, and paid my deposit.  Is it ethical to share the name of the company here?  Should I wait until I have learned whether I had a good experience?  Is there a renewable energy equivalent to the misc.comsumers newsgroup? Anyway, my system configuration will be grid-tie only for now.  I will be installing 26 or 27 BP3160 panels, and two inverters.  The reason for the ambiguity will become clear below. As you may recall, I was nervous about whether the SunnyBoy Island from SMA would ever be available in California.  William Smith reinforced my concerns.  The Island would be a great device to have if you own SMA inverters, since the backup will plug straight into these high-voltage devices.  Other manufacturers’ battery-based inverters, on the other hand, connect straight to the PV panels.  The problem, as I understand it, is that the grid-tie inverters like high voltage and low current; the battery inverters like the opposite. Given that I don’t know what to expect, I’ve decided to invest in some extra wiring.  All of the DC home runs from my PV modules will come down to a combiner box.  The taps from the combiner box will initially be wired in series for grid-tie inverters, providing high voltage.  If, in the future, I need low voltage for a battery backup, the modules themselves will not need to be rewired.  We will just add taps from the combiner box that tie the PV modules together in parallel instead of in series.  This extra pre-wiring is only costing me $700. I’ll probably buy a third inverter, if I ever install the battery backup.  The nice thing about this third inverter is that it would not need to be an expensive one.  Since it would only operate off-grid, it would not have to provide utility-grade, true sine-wave AC power. I thought that I would be eliminating my SMA vs. non-SMA inverter choice issue by making these decisions.  Nope!  I initially thought to buy two SunnyBoy 2500 inverters, and to run two strings of 13 panels each (26 total).  At signing time, the contractor offered me another option.  He thought that I might want to consider the Xantrex GT 3.0 inverters instead.  His reasons: 1. Available for the same price as the Sunny Boy 2500 2. Slightly higher efficiency than the SunnyBoy 2500 (0.6% — Is this even real?  Is it worth quibbling about?) 3. Monitoring the Xantrex units is easier because they have 10BaseT connectors (and I have a router), whereas SunnyBoy uses old-fashioned RS232, and requires a dedicated modem for each inverter 4. 3000 W capacity, allowing me to enlarge the PV array later (might be important if I ever add batteries, as I’ve recently learned to expect 10% to 20% efficiency loss in a battery system *even during those times when the grid is up*???) Here’s the catch.  The Xantrex GT 3.0 inverters have two internal legs of 1500 W each.  Each leg needs a minimum of nine panels in series to boot them up.  So the contractor suggested to me that I run three strings of nine module each, for a total of 27.  I will buy one extra module in this configuration. So, even though I sometimes feel like I’m running around in circles, I’ll ask my question.  Does anyone have an opinion about the Xantrex GT 3.0?  How does it compare to the SunnyBoy 2500?  As always, my biggest concern is reliability.  But feel free to share anything you know that would cause you to recommend one unit over another. Thanks once again! — Rainforest laid low. "Wake up and smell the ozone," Says man with chainsaw. John J. Ladasky Jr., Ph.D.

Response:

Jim Baber replied directly to SQLit: You very definitely do NOT know what you are talking about…. Mr. Ladasky does so just listen and you might learn, but I doubt it. >Hello again, folks, >I checked in here about a month ago… I agree. >I’m now wavering on installing the batteries and islanding >capabilities, at least for the time being.  The reasons are several…. I agree. >Having convinced myself to forego the batteries for now, …. >I don’t like the idea of buying inverters twice,

I agree. >John J. Ladasky Jr., Ph.D. > If I understand correctly

Jim Baber replied directly to SQLit:         John said he is changing to a grid tie system! – Hide quoted text — Show quoted text -> If you do not have an battery bank the PV sort of looses its effect. Sun up > electricity, > sun down no electricity. > When the rolling back up happens and a cloud goes by your array. How the > hell do you think the refrigerator is going to get enough power to start? > All motors can draw up to 6 times running amps for a while. A while could be > almost a second. Where are you going to get the power for this? > Grid tie is going to cost you an fortune. Forget the rebates they will never > return the expenses. You get to pay for all of the equipment for grid tie > AND maintain it. This includes the utility disconnect, metering, and > frequency control. Last time I checked into this around here that meant > separate "Utility Grade metering and controls".  Have you checked with the > serving utility about the regs your going to have to meet?  The utility will > pay you an paultry sum for the privilege of receiving the energy. Usually > 1/3 to 1/4 what you pay.

Jim Baber replied directly to SQLit: You are not at all familiar with the California program. Net metering here means that I get an equal $ credit for every kWh I put onto the grid as I am charged for when I draw from the grid. I did have to pay a $277.00 fee for a special meter ONLY because I wanted the Time Of Day rates.  These rates are to my advantage since the peak use period coincides very well with my peak solar production.  This works so well that in the past 18 months I only have had to pay PG&E about $175. (the 12 months before our bills added to $4,800) > Do you really have an understanding of what an UPS does and how big it would > need to be to run an refrigerator? Let alone and another load called an > freezer. UPS’s are not usually sized to start motors. > I am not trying to insult. Seems to me your out in an pasture some where > just grazing.

The house I refer to is 4,000 sq. ft. has 10 tons of A/C capacity, electric water heaters (2), 4 computers, 2 refrigerators, all electric kitchen, washer and electric dryer…..AND I managed to almost break even with the electric bill after 18 months on a 10kW system. By the way the system will be paid off in 4 years and 3 months at the savings I am actually seeing and the added deductions that I have on my state and federal income taxes because I refinanced the house to pay for the system. payment by the way, and the old one was variable and had 19 years to go. — Jim Baber 1350 W Mesa Ave. Fresno CA, 93711 (559) 435-9068 (559) 905-2204 (A no charge Verizon IN cellphone to other Verizon IN accounts) See our 10kW grid tied solar system at "www.baber.org"

Response:

>the battery systems are the presently the least >cost-effective part of the system, with the most room for technical >improvements.

I’d say that the most expensive part of any solar system is the panels (somewhere around $5/watt), followed by the electronics (around a buck a watt), and that batteries would be last (3 cents per KWHR). >I’m particularly dismayed that I would need to buy a >new battery bank every 4-6 years, even if my power never goes out!

That’s way too agressive.  Mediocre, poorly-maintained, offbrand golf cart batteries last 5 years in golf carts, I’d expect at least 10 years life out of a properly maintained bank of Trojan T-105 batteries, and the replacement cost is only about $500 worst-case.  [I don't know your system voltage] >Another inverter provides both grid-tie and >battery connections, but I’m told that you CAN’T RUN IT unless you >have the batteries!

But you don’t have to have a lot of expensive batteries, get a couple of cheap deep-cycle batteries or a string of T-105s and you are all set.  [Again, hard to tell without your system voltage, but Walmart has the Hawker (nee Gates) cyclon monobloc AGM deep-cycle batteries for not a whole lot of money...] >Thus, I’m leaning toward the SMA >inverters on the promise of a future upgrade path.  The only problem >is that the battery-managing device, called the Sunny Boy Island, is >apparently not yet approved for use by the California Energy >Commission.

Does the device actually exist and is it shipping to other markets? The RE market is one in which I’d take any promises of future products with a large grain of salt…

Response:

November 11, 2004 > That’s way too agressive.  Mediocre, poorly-maintained, offbrand golf > cart batteries last 5 years in golf carts, I’d expect at least 10 > years life out of a properly maintained bank of Trojan T-105

I have good luck with T-105s after they come out of the golf carts. I can usually get another few years on them with PV, and then switch them to wind, and run them until they are totally gone. Thomas Lee Elifritz http://elifritz.members.atlantic.net

Response:

Jim Baber’s response to John’s project I made comments earlier, and I can see that you have come to the same conclusions that I did. – Hide quoted text — Show quoted text – > Hello again, folks, > I checked in here about a month ago.  Your input helped me to narrow > down my list of solar PV contractors to two.  I have a few more > decisions to make, and then I’ll be ready to sign on the dotted line. > Hope y’all can help! > I’ll briefly reintroduce myself and my project.  I’m installing a PV > system on a suburban house in San Jose, California.  I have been > interested in installing some off-grid, outage-proofing capabilities > as well as grid-tie.  Our earlier discussion started here: > http://groups.google.com/groups?&selm=c09b237b.0410041639.379d3020%40… > I’m now wavering on installing the batteries and islanding > capabilities, at least for the time being.  The reasons are several.

I I also originally wanted the same off line backup that you have identified, and I came to the same conclusion that the additional costs of the batteries and charging systems that were NOT allowed as costs under the California rebate program, made current off grid operation uneconomical. My decision was validated considering that I have had 1 outage for 2.5 hours since I installed my system.  This was caused by the 1st rain this year (shorted out a nearby transformer), and I started up on Jun. 13 2003 (today is Nov. 11 2004). I actually had a first this week, I had a day that I actually had 0 kWh output all day long, it sure was dark out, I have averaged 48.71814672 since installation, > In the first place, even though we’ve had a few outages over the > years, I’ve learned that we’re in a privileged rotating outage block > — there’s a fire station located under a mile from our house.  

Strange, we have a fire station 3 blocks from the house, maybe we are also privileged. I wish > that I had paid attention to the frequency and duration of outages > that we had in 1999 and 2000 — I expect that it will get bad again > some day.  Second, the California Energy Commission only rebates the > customer for installing grid-tied generating capacity, and not for > batteries.  Finally, the battery systems are the presently the least > cost-effective part of the system, with the most room for technical > improvements.  I’m particularly dismayed that I would need to buy a > new battery bank every 4-6 years, even if my power never goes out! > The longer I can defer buying the battery system, the better I think > that I’ll do.

What I think I will do, is to buy the Sunny Boy Island when it is available. (remember I have 4 Sunnyboy 2500U inverters) If I can use the Island in conjunction with a small 5-10 kW generator set to avoid the whole battery and charging hassle I will.  A new good small generator set in this size can easily be had for less than $2,000 and is quite adequate for powering my home’s off peak emergency loads. I may be able to jury rig an auto starting system on the generator set if I have to using my control computer to start it, if I have to, but I would prefer to buy the auto start capability as an inherent part of the generator set’s options. I am sure that SMA will tie this to their existing product line, since that is the prevailing theme I have seen with their other products.  So far all of their small and medium sized inverters will work together with all of their Control units. – Hide quoted text — Show quoted text -> Having convinced myself to forego the batteries for now, I still have > to make decisions now that may affect what happens in the future when > I go to add a battery backup.  Different inverter manufacturers have > different approaches to the islanding problem.  It appears that > Xantrex requires you to commit to having your batteries at the time > that you install the inverter.  One inverter model allows grid-tie, > but no battery interface.  Another inverter provides both grid-tie and > battery connections, but I’m told that you CAN’T RUN IT unless you > have the batteries!  SMA appears to have taken a different approach. > Their inverters are grid-tie devices, with an OPTION to connect an > external islanding device and batteries. > I don’t like the idea of buying inverters twice, and having holes cut > in the wall of my house twice.  Thus, I’m leaning toward the SMA > inverters on the promise of a future upgrade path.  The only problem > is that the battery-managing device, called the Sunny Boy Island, is > apparently not yet approved for use by the California Energy > Commission.  

Using it the way I want to, I do not see how the CEC enters into it at all, since they are already be out of the picture because I got my rebate and 1st years tax credit earlier.  Unfortunately, however the Sunny Boy Island will probably need utility approval because it is an anti-islanding device and you do know PG&E’s reputation.  Of course I could ignore PG&E and just wire it in since PG&E has already inspected me. > One of my PV contractors said that the scuttlebutt is > that it will eventually be avaiable here.  I sent an email to a > marketing person at SMA-America to try to find out about whether they > had at least applied to the CEC to get the Sunny Boy Island approved. > My email wasn’t answered.  That’s not encouraging.

Try sending it to the president of SMA America John Berdner. they do have something on their website "http://www.sma-america.com/sunnyislandsizing.html" for sizing something called Sunny Island, but NO PRODUCT information. (so far) – Hide quoted text — Show quoted text -> Both PV contractors have advised me to add a sub-panel of circuit > breakers that I’ll eventually want to supply with the battery backup. > I like this idea better than the separate emergency that we discussed > earlier.  At the very least, I would want uninterruptable power to my > refrigerator/freezer.  I’d prefer not to drive home from work, only to > find that I’d lost power six hours earlier, and that I wouldn’t have > spoiled food if only I’d driven home to transfer the power cord from > one outlet to the other… > Do I understand everything that I’ve been told correctly? > Thanks again for your expert advice! > — > Rainforest laid low. > "Wake up and smell the ozone," > Says man with chainsaw. > John J. Ladasky Jr., Ph.D.

– Jim Baber 1350 W Mesa Ave. Fresno CA, 93711 (559) 435-9068 (559) 905-2204 (A no charge Verizon IN cellphone to other Verizon IN accounts) See our 10kW grid tied solar system at "www.baber.org"

Response:

Hi, Anthony, Good to hear from a fellow Californian.  Thanks for setting "SQLit" straight.  Either SQLit does not live in a net-metering state, or does not understand the concept of net-metering.  Normally, I can find it in myself to respond politely to posts such as that one.  For whatever reason, I could not do so this time. > My two cents for the original poster runs like this… > There is a market for used inverters so if you happen to want another > model some time in the future the "old" one wouldn’t be a total loss. > If you replace one inverter with another then you should be able to > use the same holes in the walls for the wires. Even if you can’t, > holes in the walls are fairly easily repaired. Cover the messy fixes > to the walls with a big sign describing the system. > You will note that the rebates do not require that you keep the stuff > connected forever (or any amount of time). You can sell it all off the > moment their check clears.

Well, I certainly don’t intend to sell anything right away.  But it’s good to know that I could trade in the inverters, if I had to. > You may want to see if you can arrange to have the rebates get paid > to your vendor/installer/PV supplier. Whoever receives the rebates > has to declare them as income and pay taxes on it. The PV seller > has to pay taxes on their income anyhow so it won’t cost them anything > but floating the money until the government pays.

Yes, both of the contractors I’m considering will apply for the CEC rebates for me, and float me the money. > I too would suggest the separate panel for circuits you want powered > in an emergency. When you lose power the contents of the fridge won’t > spoil for several hours and the freezer for over a day. You could buy > a small generator (perhaps natural gas or propane fueled) that could > power these circuits for now using an automatic or manual transfer > switch. Later you can add more expensive (and more environmentally > friendly) ways to power everything. You don’t have to do everything > at once.

Right, that’s exactly what I’m planning.  Grid-tied solar now, to get free of the utility company’s financial clutches — and to free my conscience as an electricity consumer.  Worry about how to use off-grid PV power at a later date, when battery technology is cheaper and outages are more frequent. You seem to be expressing the opinion that, because they can be resold, it doesn’t matter whether I choose SMA or Xantrex inverters now. I was really hoping to hear from someone about the Sunny Boy Island. A user in the UK, perhaps?  I want to know whether it’s worth planning around this product, even though California won’t let me have one connected to a grid-tied system (yet). > http://www.northerntool.com/webapp/wcs/stores/servlet/ProductDisplay?… > For instance, the above generator (Generac Centurion Automatic Standby > Generator 3400 watts) uses two propane tanks, auto starts on power > failure and has it’s own "subpanel" in the form of a power strip that > can be user installed inside the house. Northern Tool is selling them > for $1800.

I might go with a gas-powered generator.  Then again, I might just tough it out for a few years. > Anthony

– Rainforest laid low. "Wake up and smell the ozone," Says man with chainsaw. John J. Ladasky Jr., Ph.D.

Response:

> …I’m particularly dismayed that I would need to buy a new battery >bank every 4-6 years, even if my power never goes out!

Unused batteries last longer, esp if kept cold, in a small fridge? > …It appears that Xantrex requires you to commit to having your > batteries at the time that you install the inverter.  One inverter > model allows grid-tie, but no battery interface.  Another inverter > provides both grid-tie and battery connections, but I’m told that > you CAN’T RUN IT unless you have the batteries!

Investigate further. You may find the "battery Xantrex" you have in mind will work in grid-tie-only mode with very few batteries, eg two. Years ago, I heard one Xantrex engineer describe their tests with a 4024(?) and two old absolutely dead Diehards from a junkyard. The grid-tie mode worked fine, even though the batteries wouldn’t hold a charge long. They just acted as high-ripple current capacitors, with large 60 Hz currents. Nick

Response:

… > If you do not have an battery bank the PV sort of looses its effect. Sun up > electricity, > sun down no electricity.

This is correct as long as you don’t have a grid. With a grid it means Sun up, you put electricity into the grid, Sun down you take electricity out. > When the rolling back up happens and a cloud goes by your array. How the > hell do you think the refrigerator is going to get enough power to start? > All motors can draw up to 6 times running amps for a while. A while could be > almost a second. Where are you going to get the power for this?

With a grid tie and no batteries the inverter shuts down because it’s designed not to operate without the grid. That means no grid, no power. > Grid tie is going to cost you an fortune. Forget the rebates they will never > return the expenses. You get to pay for all of the equipment for grid tie > AND maintain it. This includes the utility disconnect, metering, and > frequency control. Last time I checked into this around here that meant > separate "Utility Grade metering and controls".  Have you checked with the > serving utility about the regs your going to have to meet?  The utility will > pay you an paultry sum for the privilege of receiving the energy. Usually > 1/3 to 1/4 what you pay.

Here in California we have net metering laws. The grid has to buy the power from you for the same amount you pay them. The utility supplies the meter (a typical home meter suffices as it runs both forward and backwards) and only bills you the difference between what you use and what you produce. Grid tied inverters provide all the frequency and voltage control required and the utility disconnect is simply a switch. Maintenance on a grid tied system amounts to cleaning off the panels when they get dusty (a couple of times a year) and making sure no animals have been chewing on the wires or nesting inside the inverter. The panels are expected (and warranted) for 25 years and the inverters typically have 3 to 5 year warranties and both can be reasonably expected to last quite a bit longer than their warranty periods. The rebates won’t pay for all the equipment but they can pay for half of it which makes it a reasonable long term investment. Reason, of course, doesn’t have to enter into the buying decision but it helps. My two cents for the original poster runs like this… There is a market for used inverters so if you happen to want another model some time in the future the "old" one wouldn’t be a total loss. If you replace one inverter with another then you should be able to use the same holes in the walls for the wires. Even if you can’t, holes in the walls are fairly easily repaired. Cover the messy fixes to the walls with a big sign describing the system. You will note that the rebates do not require that you keep the stuff connected forever (or any amount of time). You can sell it all off the moment their check clears. You may want to see if you can arrange to have the rebates get paid to your vendor/installer/PV supplier. Whoever receives the rebates has to declare them as income and pay taxes on it. The PV seller has to pay taxes on their income anyhow so it won’t cost them anything but floating the money until the government pays. I too would suggest the separate panel for circuits you want powered in an emergency. When you lose power the contents of the fridge won’t spoil for several hours and the freezer for over a day. You could buy a small generator (perhaps natural gas or propane fueled) that could power these circuits for now using an automatic or manual transfer switch. Later you can add more expensive (and more environmentally friendly) ways to power everything. You don’t have to do everything at once. http://www.northerntool.com/webapp/wcs/stores/servlet/ProductDisplay?… For instance, the above generator (Generac Centurion Automatic Standby Generator 3400 watts) uses two propane tanks, auto starts on power failure and has it’s own "subpanel" in the form of a power strip that can be user installed inside the house. Northern Tool is selling them for $1800. Anthony

Response:

> Hello again, folks, > I checked in here about a month ago.  Your input helped me to narrow > down my list of solar PV contractors to two.  I have a few more > decisions to make, and then I’ll be ready to sign on the dotted line. > Hope y’all can help! > I’ll briefly reintroduce myself and my project.  I’m installing a PV > system on a suburban house in San Jose, California.  I have been > interested in installing some off-grid, outage-proofing capabilities > as well as grid-tie.  Our earlier discussion started here:

http://groups.google.com/groups?&selm=c09b237b.0410041639.379d3020%40… – Hide quoted text — Show quoted text -> I’m now wavering on installing the batteries and islanding > capabilities, at least for the time being.  The reasons are several. > In the first place, even though we’ve had a few outages over the > years, I’ve learned that we’re in a privileged rotating outage block > — there’s a fire station located under a mile from our house.  I wish > that I had paid attention to the frequency and duration of outages > that we had in 1999 and 2000 — I expect that it will get bad again > some day.  Second, the California Energy Commission only rebates the > customer for installing grid-tied generating capacity, and not for > batteries.  Finally, the battery systems are the presently the least > cost-effective part of the system, with the most room for technical > improvements.  I’m particularly dismayed that I would need to buy a > new battery bank every 4-6 years, even if my power never goes out! > The longer I can defer buying the battery system, the better I think > that I’ll do. > Having convinced myself to forego the batteries for now, I still have > to make decisions now that may affect what happens in the future when > I go to add a battery backup.  Different inverter manufacturers have > different approaches to the islanding problem.  It appears that > Xantrex requires you to commit to having your batteries at the time > that you install the inverter.  One inverter model allows grid-tie, > but no battery interface.  Another inverter provides both grid-tie and > battery connections, but I’m told that you CAN’T RUN IT unless you > have the batteries!  SMA appears to have taken a different approach. > Their inverters are grid-tie devices, with an OPTION to connect an > external islanding device and batteries. > I don’t like the idea of buying inverters twice, and having holes cut > in the wall of my house twice.  Thus, I’m leaning toward the SMA > inverters on the promise of a future upgrade path.  The only problem > is that the battery-managing device, called the Sunny Boy Island, is > apparently not yet approved for use by the California Energy > Commission.  One of my PV contractors said that the scuttlebutt is > that it will eventually be avaiable here.  I sent an email to a > marketing person at SMA-America to try to find out about whether they > had at least applied to the CEC to get the Sunny Boy Island approved. > My email wasn’t answered.  That’s not encouraging. > Both PV contractors have advised me to add a sub-panel of circuit > breakers that I’ll eventually want to supply with the battery backup. > I like this idea better than the separate emergency that we discussed > earlier.  At the very least, I would want uninterruptable power to my > refrigerator/freezer.  I’d prefer not to drive home from work, only to > find that I’d lost power six hours earlier, and that I wouldn’t have > spoiled food if only I’d driven home to transfer the power cord from > one outlet to the other… > Do I understand everything that I’ve been told correctly? > Thanks again for your expert advice! > — > Rainforest laid low. > "Wake up and smell the ozone," > Says man with chainsaw. > John J. Ladasky Jr., Ph.D.

If I understand correctly If you do not have an battery bank the PV sort of looses its effect. Sun up electricity, sun down no electricity. When the rolling back up happens and a cloud goes by your array. How the hell do you think the refrigerator is going to get enough power to start? All motors can draw up to 6 times running amps for a while. A while could be almost a second. Where are you going to get the power for this? Grid tie is going to cost you an fortune. Forget the rebates they will never return the expenses. You get to pay for all of the equipment for grid tie AND maintain it. This includes the utility disconnect, metering, and frequency control. Last time I checked into this around here that meant separate "Utility Grade metering and controls".  Have you checked with the serving utility about the regs your going to have to meet?  The utility will pay you an paultry sum for the privilege of receiving the energy. Usually 1/3 to 1/4 what you pay. Do you really have an understanding of what an UPS does and how big it would need to be to run an refrigerator? Let alone and another load called an freezer. UPS’s are not usually sized to start motors. I am not trying to insult. Seems to me your out in an pasture some where just grazing.

Response:

Hello again, folks, I checked in here about a month ago.  Your input helped me to narrow down my list of solar PV contractors to two.  I have a few more decisions to make, and then I’ll be ready to sign on the dotted line. Hope y’all can help! I’ll briefly reintroduce myself and my project.  I’m installing a PV system on a suburban house in San Jose, California.  I have been interested in installing some off-grid, outage-proofing capabilities as well as grid-tie.  Our earlier discussion started here: http://groups.google.com/groups?&selm=c09b237b.0410041639.379d3020%40… I’m now wavering on installing the batteries and islanding capabilities, at least for the time being.  The reasons are several. In the first place, even though we’ve had a few outages over the years, I’ve learned that we’re in a privileged rotating outage block — there’s a fire station located under a mile from our house.  I wish that I had paid attention to the frequency and duration of outages that we had in 1999 and 2000 — I expect that it will get bad again some day.  Second, the California Energy Commission only rebates the customer for installing grid-tied generating capacity, and not for batteries.  Finally, the battery systems are the presently the least cost-effective part of the system, with the most room for technical improvements.  I’m particularly dismayed that I would need to buy a new battery bank every 4-6 years, even if my power never goes out! The longer I can defer buying the battery system, the better I think that I’ll do. Having convinced myself to forego the batteries for now, I still have to make decisions now that may affect what happens in the future when I go to add a battery backup.  Different inverter manufacturers have different approaches to the islanding problem.  It appears that Xantrex requires you to commit to having your batteries at the time that you install the inverter.  One inverter model allows grid-tie, but no battery interface.  Another inverter provides both grid-tie and battery connections, but I’m told that you CAN’T RUN IT unless you have the batteries!  SMA appears to have taken a different approach. Their inverters are grid-tie devices, with an OPTION to connect an external islanding device and batteries. I don’t like the idea of buying inverters twice, and having holes cut in the wall of my house twice.  Thus, I’m leaning toward the SMA inverters on the promise of a future upgrade path.  The only problem is that the battery-managing device, called the Sunny Boy Island, is apparently not yet approved for use by the California Energy Commission.  One of my PV contractors said that the scuttlebutt is that it will eventually be avaiable here.  I sent an email to a marketing person at SMA-America to try to find out about whether they had at least applied to the CEC to get the Sunny Boy Island approved. My email wasn’t answered.  That’s not encouraging. Both PV contractors have advised me to add a sub-panel of circuit breakers that I’ll eventually want to supply with the battery backup. I like this idea better than the separate emergency that we discussed earlier.  At the very least, I would want uninterruptable power to my refrigerator/freezer.  I’d prefer not to drive home from work, only to find that I’d lost power six hours earlier, and that I wouldn’t have spoiled food if only I’d driven home to transfer the power cord from one outlet to the other… Do I understand everything that I’ve been told correctly? Thanks again for your expert advice! — Rainforest laid low. "Wake up and smell the ozone," Says man with chainsaw. John J. Ladasky Jr., Ph.D.

Response:

… > Now, the maximum voltage in James’ setup should be (28.9V/module + > (0.112 V/