Mixing PV and wind

I have seen very few homes with solar energy that have wind turbines. The lands that I am looking to buy in seem to have enough of both sunshine and wind to make either a viable alternative. I was wondering if anyone out there has used both together. My reasons for asking....in every place I have lived in, the wind becomes stronger during the evening, but of course, there is no electricity being generated from the PV panel. By using both of them, I would think it would be possible to reduce the number of panels and batteries purchased as well as the equipment required to control them. On the days when there is no sun, usually the wind is stronger, so the turbine would help compensate for the loss of power from the PV panel. Also, if no additional electricity is needed, the turbine could be stalled so that it does not produce electricity - much easier than turning off solar panels.

Either method would require a significant financial investment, so most people just choose the one that makes most sense for their particular property. Turbines aren't as quiet as PV panels and require more maintenance. I gather you don't have electricity close by you can use, and that will require expensive batteries that will need replacing. My PV panels produce electricity during the day, and the electric company provides it at night. I produce enough during the day so the electric company pays me for the extra energy I produce.

What I don't like about my system is code won't allow me to get power from my panels when power is down from the electric company, and the electric company insists I pay their nuisance minimum fee every month (about $1.85), even though they are allowed to wait a year to pay me for power I've produced and they've sold to others (at a significantly higher rate than what they pay me).

I haven't bought the property yet. That is why I am snooping out these options to see what the "true" cost of the property is going to be.

Tom,

Wind and solar outputs must be run through separate inverters, so the cost is significantly higher than for one or the other. I was just asked yesterday about this by a client that I installed a 2000 watt solar array, 4000 watt inverter and battery bank for about $12,000. He wished to add wind to the mix, but we ran the numbers and it would cost another $12,000 for wind as well. That's not fiscally feasible. So, instead we looked for ways to reduce usage.

Bill Bradbury wrote:

Wind and solar outputs must be run through separate inverters, so the cost is significantly higher than for one or the other..

Bill, do you mean that they need separate charge controllers? I know very little about all this, but I would have thought that since the inverter comes between the batteries and the end use, the inverter wouldn't care how the batteries were being charged, so long as whatever is charging them is being controlled properly?

Here's a Chinese company that sells hybrid solar-wind systems. They appear to have a charge controller that handles both solar and wind...

And here are some more schematics that seem suggest it can be done... though all these links may well be fantasy for all I know...

Yes, separate charge controllers are needed, but only one inverter.

I'm still not a big fan of small-scale wind power. Bang for the buck; micro-hydro wins hands down. That's where I would look to supplement solar.

For sure, microhydro is nice... if you have a source of running water to borrow from.

On the input side, solar and wind complement each other well, as you so correctly observed. It also holds true in many places seasonally. Around here (michigan) the sun is gone 5 months of the year, but the wind is pretty good in the winter.

Here's the downside to wind, the tower. Wind turbines are not very efficient in "dirty" wind. That's wind that has been mangled by buildings and trees and become turbulent. So, the general recommendation is for the wind turbine to be 30 feet above every building and tree within 1-200 feet. Unless you're in the middle of naked plains kansas, and aren't going to plant any trees, this usually translates into a tower that's a minimum of 50', and 100' requirement is very common.

50 and 100' towers require a significant amount of engineering to prevent death and destruction in high winds, blah blah blah. So this usually means the tower costs more, and often far more, than the turbine itself. And who is going to do the required maintenance on that turbine 70 or 100' in the air??

It gets worse, many jurisdictions have more or less outlawed home built towers. If you go price an 80' tower, including engineering stamps, code approval, and construction. 10-25 grand disappears in a hurry. And check out if your insurance covers a tower and a turbine, and possible liability problems.



Well gee, that all sounds pretty discouraging.


Yet, there are times and places where wind makes sense as a complement to solar, especially if you are not under the thumb of the building code yahoos, meaning no disrespect to the good code enforcement folk.


Hands down the best forum for home brew wind, (and solar for that matter) is over at OtherPower:

http://www.fieldlines.com/



Really, I mean this in the helpful way...



troy

Hi Tom,

I've been using wind and solar with separate controllers to the same battery bank for over twenty years and the system works just fine - it's thanks to the complementarity of these energies that our stored electricity is always available.

If you type "hybrid solar controller" into a search engine : https://www.google.fr/search?q=hybrid+solar+controller&ie=utf-8&oe=utf-8&gws_rd=cr&ei=CQfEVLXhEcn5UPqNgLgB You can see that there are thousands of different types and sizes available and for a customised system, it's not too difficult to combine separate controllers for each energy source to charge the same battery bank.

Every site is different but if you have good wind and can site a turbine where you can capture it - then use it !

It can be relatively cheap to add a wind turbine to a solar system as you already have a battery bank. Buy a good quality turbine with a voltage/phase controller, cable from the turbine to your home (The thickness depending on the wattage and voltage of your turbine), a controller, a dump load and of course extra wiring, fuses and connections for the batteries. A source of energy which operates 24h a day when the sun is hiding, can be a blessing.

The system you design also depends on you and how much energy you feel you need and what your budget is.

We started with just a few hundred watts of wind and solar and have crept up gradually to having almost a "normal" house but that way of doing things doesn't suit everyone. I like knowing exactly how our system is balanced and what's going on when the sun shines or the wind blows and being able to change over to another system when one shows signs of not being able to equalise the batteries. I guess it's become a sort of hobby with me to see just how little we can get away with and still have as much electricity as we need. That doesn't suit everyone of course - you may want a system to behave exactly as though you're grid connected and not be bothered with technical details.

Also, if no additional electricity is needed, the turbine could be stalled so that it does not produce electricity - much easier than turning off solar panels.

I just thought I'd add that turning off solar panels is very easy - just a switch and you can let them "float" but in the spirit of permaculture, why not use the energy to heat water, wash clothes, pump water, heat thermal mass in a greenhouse....and so on....

We have both wind and solar at our place. Bought it like that. The wind turbine has it's own charge controller with a dump load, etc. built in. The supplemental power is nice, but for the amount of cash outlay associated with the wind turbine you could more than make up for the electricity produced by adding a significant amount of solar. It's not going to make more power at night, but in less than optimal conditions you could add enough solar panels to make the same amount of energy, and in optimal conditions you would be making a whole heck of a lot more.

I guess the bottom line is that you could probably build a solar array four times the size (kwh) for the same amount of money (i.e. 1kw wind, 4kw solar). Just something to think about especially if you aren't in prime wind energy country, and most of us aren't.

Jim Gardener wrote:What I don't like about my system is code won't allow me to get power from my panels when power is down from the electric company, and the electric company insists I pay their nuisance minimum fee every month (about $1.85), even though they are allowed to wait a year to pay me for power I've produced and they've sold to others (at a significantly higher rate than what they pay me).

Some of the SMA inverters are now available with a single isolated outlet in addition to the regular output; when grid power goes down, that outlet can stay on as long as there's enough input from the array. It's been a big selling point for us in that a lot of customers just want to make sure they can keep a big freezer frozen or charge a cell phone in an extended power outage, without the added expense of a battery bank.

As for mixing wind and solar, the only turbine we've sold in the last two years was a used one to a guy who wanted it mainly for looks. The price of solar has dropped so much in the last few years that we can install three times as much capacity in solar as wind for the same price. Add to that, that solar has longer warranties and no moving parts to wear out, and it's a no-brainer. Wind is fun to play with, but not really economical for normal residential and small commercial electric generation.

That may well be the case but it's thanks to the wind that I'm reading the posts in the forum tonight !

That new inverter sounds nice, but they are too expensive to replace a working one, just for an outlet. I have a SMA Sunny Boy 6000-US that I replaced a couple of years ago. They are a real hassle to raise up to mount on a wall (very heavy).

Jim Gardener wrote:That new inverter sounds nice, but they are too expensive to replace a working one, just for an outlet. I have a SMA Sunny Boy 6000-US that I replaced a couple of years ago. They are a real hassle to raise up to mount on a wall (very heavy).

There's a reason most of our display equipment has the guts removed. Sales reps aren't exactly the best choice for lugging heavy stuff around. Each install crew has at least one gorilla-like guy who does most of the (literal) heavy lifting like handing modules up to the crew on the roof and hanging the inverter.