Solar power anyone ?

[dmccarty]

Sunny Boy (SMA America) now has a line of string inverters that will produce up to 1500 watts (at a dedicated outlet connected to the inverter) while the grid is down, and of course the sun is shining.

Outback and a couple others now offer a "grid-interactive" central inverter. It is a bus-bar based inverter that has a separate relay for the grid-tied line. If utility power is lost, this relay opens to disconnect from grid, but the home is still fed on the "backup" breaker panel from solar panels and/or batteries. They have smaller inverters in GT/GV series, but their Radian series has dual AC input where you can connect generator to charge batteries in event of low solar output while disconnected from grid. This beats having to buy two inverters to accomplish the same thing.

Outback Power Inc. - Grid-Interactive

The Sunny Boy models, as I posted earlier, do not sound like they would work safely with motors, which would rule out fridges, freezers, and well pumps. I could care less about lights. The dedicated outlet is only marginally useful.

I looked at documentation on the Outback site, which has some confusing text, but I cannot find where they state their inverters will run, without batteries AND grid power. From the GTFX and GVFX specifications document, http://www.outbackpower.com/downloads/documents/gtfx_gvfx_series/ob_022013_gtfxgvfxseries_specsheet_lr.pdf

Our built in transfer switch automatically disconnects your loads from the utility grid and powers them from the inverter in the event of an outage, allowing you to continue using your solar and battery back-up power, unlike traditional grid-tie systems.

The marked text can be read a couple of ways but I think it means one needs batteries if the grid goes down.

The inverter manual did not mention anything on this subject that I could find. This page, Outback Power Inc. - Grid-Interactive has a diagram that shows batteries.

Is there a document on their website that has more details?

Later,
Dan

 

[westcliffe01]

Grundfos SQFlex Submersible Solar Well Pumps

Just to be clear, there are plenty of solutions that work for providing well water from solar. Generally speaking though, the flow rate does not equal a multi HP conventional well pump. But then the mode of operation is not the same either. One either installs an oversized accumulator, or installs a cistern with a float switch and the solar powered well pump can take its sweet time filling the cistern. When you need water (when pressure drops in the domestic line) then you have a much lower powered pump which lifts the water from the cistern into the house system and you could easily have a couple of thousand gals of water available if needed. Most wells in this area are around 500+ ft deep.

I am looking a building an off the grid home and have spent the last week looking at property in southern CO. There are plenty of people living this kind of life, the key thing is to configure the site/home for minimal energy demand in the first place. The site I am looking at is at 9000ft so no need for AC and has a high % of sunny days and the home will be built passive solar. All light fixtures will be LED. My home will not be very large, be almost entirely concrete (for thermal mass) and built into a south facing slope so only the southern side will be fully exposed and the east/west partially so.

I will also have a shop and that will be equipped with a diesel genset modified for CO-gen, thus recovering a lot of heat from the exhaust, coolant and oil. The primary heating system for the buildings will be water based radiant, in the slab with multiple circuits. Solar collectors will feed a buried/insulated cistern (installed under the grow beds in the greenhouse) and that in turn will als b fed by the co-gen system (when in use) as well as a diesel fired hot water heater. I have looked into all fuel sources and diesel is a common fuel for all my equipment, and I can buy it myself from many sources so I'm not held captive by 1 or 2 propane distributors. It also has a high energy density and I can transport it myself.

In my case this remote land is relatively cheap and the price for that is a lack of infrastructure and unreliable access (weather related) so for 3 months of the year it might take a arctic cat or snowmobile to get out to a maintained road. Conventional utilities are basically out of the question and the solution to that is part of the cost of building.

 

[TnAndy]

The GT/GV series is set to run on a specific voltage......12,24, 48 + a volt or two on the high side, and down a couple volts on the low side ( before they shut down due to low voltage ). Only way to do that is with a battery bank. Panel voltage will vary all over the place based on the amount of sun on the panels.

They are set up with a large positive and negative power lug on each that is fed from a battery bank ( thru a fused/breaker disconnect ), so you really don't have a way to feed in small wires from panels TO the inverter.

The setup is: Panels to charge controller ( where panel voltage is changed to match battery voltage, assuming you're using an MPPT controller, like the Outback FX series ), then battery, then inverter.....with the required fusing and disconnecting means between each component, and AC breakers on the output side.


The Radian, I have no experience with, and can't speak to how it works.

 

[TnAndy]

Grundfos SQFlex Submersible Solar Well Pumps

Just to be clear, there are plenty of solutions that work for providing well water from solar. Generally speaking though, the flow rate does not equal a multi HP conventional well pump. But then the mode of operation is not the same either. One either installs an oversized accumulator, or installs a cistern with a float switch and the solar powered well pump can take its sweet time filling the cistern. When you need water (when pressure drops in the domestic line) then you have a much lower powered pump which lifts the water from the cistern into the house system and you could easily have a couple of thousand gals of water available if needed. Most wells in this area are around 500+ ft deep.

Sounds like a real setup !

We use gravity fed spring water for our home. 3,000 gallons of storage tanks located up on the mountain near the spring.

 

[westcliffe01]

Solar Water Pumping Guide

Nice write up (guideline) regarding solar water pumping.

 

[rmorey]

Sounds like a real setup !

We use gravity fed spring water for our home. 3,000 gallons of storage tanks located up on the mountain near the spring.

I've been reading this thread with interest. We recently moved to a retirement home, 200 acres on a lake. Built a home and workshop, called the hydro folks, who told us that "hydro is $150,000 due south of you"!

After the adrenaline rush subsided, we researched, and installed an off grid 3.6kw (20 - 180 watt panels), 2 - FM80 Charge Controllers, with a pair of Magnum 4,000 watt inverters, 24 - 2v Trojan 1110 amp batteries, configured as 2 - 1110 amp strings (big box in the basement). All for around $25K. (sorry, no subsidies here). Our savings come in the form of no power bills ever. We also have an 8500 watt gas generator for those dull periods.

We have a 240 v submersible water pump, fridge, freezer, lights etc. Our daily consumption is about 150 amps dc, converting to, give or take, 4Kw.

With regards to the question of no power from the micros when the grid goes down, why wouldn't a small battery backup, say 4 - 6v batteries, 225 amp with a small charge controller/inverter work? Would be cheap to install (< $1k) and give you enough power to run water, freezer/fridge and some lites.

 

[dmccarty]

With regards to the question of no power from the micros when the grid goes down, why wouldn't a small battery backup, say 4 - 6v batteries, 225 amp with a small charge controller/inverter work? Would be cheap to install (< $1k) and give you enough power to run water, freezer/fridge and some lites.

In the solar class I took earlier in the year, we discussed if it was possible to trick the inverters into thinking there was grid power. We came up with the ideas of using batteries but it is going to depend on how the inverters determine a grid outage. The bottom line seems to be that you really need batteries when the grid goes down are you risk damaging equipment that is sensitive to power fluctuations.

Later,
Dan

 

[TnAndy]

I've not tried it with my system, nor will I unless the grid goes down and looks to be down a long time, maybe forever....( like an EMP event, or a solar flare, etc ), but I'm fairly sure I could rewire the micro inverter portion of my system to connect with the off grid portion of my system ( the hybrid Outbacks ) so I could utilize the whole 11kw, at least during sunny hours, since the Outback inverters put out as clean ( or better ) power as the utility input. 240v 60hz power is the same, no matter where it comes from.

 

[TnAndy]

I've been reading this thread with interest. We recently moved to a retirement home, 200 acres on a lake. Built a home and workshop, called the hydro folks, who told us that "hydro is $150,000 due south of you"!

After the adrenaline rush subsided, we researched, and installed an off grid 3.6kw (20 - 180 watt panels), 2 - FM80 Charge Controllers, with a pair of Magnum 4,000 watt inverters, 24 - 2v Trojan 1110 amp batteries, configured as 2 - 1110 amp strings (big box in the basement). All for around $25K. (sorry, no subsidies here). Our savings come in the form of no power bills ever. We also have an 8500 watt gas generator for those dull periods.

Not to mention the $100,000+ you didn't shell out to bring the power line to you. Your payback was about one second after you fired up the system !

With regards to the question of no power from the micros when the grid goes down, why wouldn't a small battery backup, say 4 - 6v batteries, 225 amp with a small charge controller/inverter work? Would be cheap to install (< $1k) and give you enough power to run water, freezer/fridge and some lites.

One would basically be building a larger UPS like those used on computers, charged by line power, and only used in grid down. The problem would be size of battery storage. You're not gonna run pump, freezer/fridge and lights TOO long off a 24v 225amp/hr battery setup....assuming 50% depth of battery discharge, by the time you convert it to AC, you're only looking at about 1/2kw/hr. Average US home use is about 30kw/hrs/day......you can see 1/2kw/hr isn't gonna go too awful far.

That is exactly the problem with those "solar generators" they sell for 2,000-3,000 bucks ( or more ).....they would lead you to believe you have 1500 to 2000watts of power like a small gasoline generator....which you do.....for about 20 minutes if using the max. Then the small panel setup they sell with it is going to take 2-3 days of sunny weather to let you do that again.

 

[SPYDERLK]

People need batteries because batteries are required to provide backup power when there is a power outage. People are shocked when the find out that a grid tied system is not usable during a power outage.
Later,
Dan

Oh me, I'm as confused as ever now! :confused2: my normal state.

So, no batteries, no good when power goes out? Maybe I should have some solar boys come give me explanation and estimate.

Can anybody explain why a simple automatic drop out switch arrangement would not suffice to break from the mains in a power outage, leaving your array connected to your panel? With this option you could probably do with minimal batteries just to supply ride thru of nulls caused by clouds.
Thanks,
,,,,larry