Wind-Solar Hybrid for Car-Charging Applications

bikiranguha

Hi all,

I have been doing some research about how renewable energy is used for electric and hybrid vehicle charging applications. Although solar is being used, use of wind and wind-solar combination is not used (at least from what i have gathered from the net).

However, research considers that wind-solar hybrid has great potential (<http://cleantechnica.com/2013/05/01/...-as-efficient/) and has been tested and optimized for powering homes. SO, why not cars?

I have not been able to find the answer to that on net. I do hope you guys can help me out.

Bikiran

solar_dave

Re: Wind-Solar Hybrid for Car-Charging Applications

Wind requires a pretty specific good wind site. They are few and far between, generally small wind requires high towers, good turbines and lots of wind to compete with solar. The wind capital costs are also higher per watt in general.

BTW I used grid tie solar to charge our two Chevy Volts. We have Lousy wind potential.

mike95490

Re: Wind-Solar Hybrid for Car-Charging Applications

What answer are you looking for ?

Any properly designed system can integrate solar PV and wind power (site permitting) and feed it to any storage device, house battery or car battery. Even hydro can be added for 3 way power input.

Put if the site has no proper sun or wind, that element drops out, and is not even worth installing.

bikiranguha

Re: Wind-Solar Hybrid for Car-Charging Applications

So, if there is not enough wind in a sunny area, its not worth installing. If we look at it that way, then it seems that all the places where solar docking stations have been installed don't have much wind potential. But there are quite a lot being constructed right now, and none of them even mentions about integrating with wind.

There must be other problems, like cost of integration or control or monitoring. I want to know exactly what they are.

westbranch

Re: Wind-Solar Hybrid for Car-Charging Applications

This is one BIG reason NOT to install a turbine in a congested (populated) area

http://www.youtube.com/watch?v=CqEccgR0q-o

http://www.youtube.com/watch?v=-YJuFvjtM0s

mike95490

Re: Wind-Solar Hybrid for Car-Charging Applications

Most areas with useable wind, are uninhabitable. That much wind is just not comfortable.

BB.

Re: Wind-Solar Hybrid for Car-Charging Applications

You have two ways of charging vehicles... One is to dump power directly into the vehicle (i.e., park vehicle next to solar array from 9am to 3pm...

Or, have some sort of "storage system" you can charge when the Renewable Energy is available (daytime with solar) and recharge the vehicle at the owner's schedule (night time).

If you do this with local battery bank--Expensive and some limitations (i.e., you need more battery and solar panels if you want to charge more than one vehicle per day).

If you do this with a Grid Tied power system, you basically "recharge the grid" (turn the meter backwards) with wind/solar/etc. and you can plug the car in any time to recharge. Also, with the grid--The power can be generated remotely for use locally.

So--Technically, there is a lot of wind and solar (and other RE sources) that run the grid--So they can recharge the electric/hybrid vehicles too.

Solar tends to be the most predictable and least impact for local generation. Wind/Hydro/etc. are not generally available in metro areas and not very practical to retrofit into a parking lot/etc.

Are you trying to avoid grid connected charging stations? For roughly the same amount of kWH per day, an off grid system using lead acid battery banks (charge during day) for charging a vehicle (at night), will cost you (very roughly) 4x more than a grid connected system with no local storage that is using the grid.

-Bill

bikiranguha

Re: Wind-Solar Hybrid for Car-Charging Applications

BB. wrote: »

Are you trying to avoid grid connected charging stations? For roughly the same amount of kWH per day, an off grid system using lead acid battery banks (charge during day) for charging a vehicle (at night), will cost you (very roughly) 4x more than a grid connected system with no local storage that is using the grid.

-Bill

Well, can you show me how a standalone system can cost 4x more than a grid connected one? This is very surprising to me. I thought grid connected setup was more complicated and expensive.

solar_dave

Re: Wind-Solar Hybrid for Car-Charging Applications

bikiranguha wrote: »

Well, can you show me how a standalone system can cost 4x more than a grid connected one? This is very surprising to me. I thought grid connected setup was more complicated and expensive.

The Grid connected chargers are the least complex, no external battery to contend with, no charge controller for those external batteries. No large inverter to take DC and convert to higher AC 240V required by most on-board car chargers. No losses from all those transitions.

Grid tie is simply an inverter that takes the DC from panels and converts it to AC matching the grid frequency and voltage. Most claim a 95% or better conversion efficiency.

BB.

Re: Wind-Solar Hybrid for Car-Charging Applications

Grid connections are "dirt cheap"... Solar panels+GT inverter plus racking turnkey installed--Around $3-$5 per Watt. Just a branch circuit to your existing main panel (assuming panel is large enough to support desired solar array).

Price out an off grid system, adding a battery bank, replacement of the battery bank every 3-10 years, and that a GT system is rough 77% efficient (AC panel ST rating to usable AC Watts to grid), vs Off Grid system which is around 52% efficient for Panel STC Rating to Usable AC power out.

And--you can only store around 1-3 days of sun with an Off Grid system, vs you can "store power" for up to one year with a Grid Tied system (i.e., I generate way more power than I use in the summer, and a draw on that "bank" in the winter--In fact, I draw a negative amount in my "bank" during winter and refill it the next summer (my "true up" period is October to September). You cannot do that with a battery bank.

So, overall, you need about 2x the solar array for an off grid system of equivalent power, and battery bank+cabling+breakers+OG Inverter+Backup Generator+Fuel (if you need emergency backup power). And all the extra maintenance.

If you wish, give us a location (so we can estimate hours of sun) and how many kWH per day you need for vehicle charging--And we can run some quick numbers and see what we get.

I am not trying to argue from authority--I am just saying that is what I/we have, generally, seen when we "run the numbers". It is possible to do better with Off Grid Power if you are willing to accept limitations (1 day of power storage, deeper cycling of battery bank, no backup genset/power source, etc.).

And at the same time not every state/utility charges/treats solar power the same way for Grid Tied. In California, it is "illegal" for me to install an off grid power system and leave the grid without paying fees to the utility for "stranding their assets" (basically the 20-40 year "investments" that my property has been used to back revenue bonds/investments).

It is an interesting project to do a paper design.

-Bill

Eric L

Re: Wind-Solar Hybrid for Car-Charging Applications

Well, can you show me how a standalone system can cost 4x more than a grid connected one? This is very surprising to me. I thought grid connected setup was more complicated and expensive.

Just look at the battery cost alone. If you need 10 kWh/day (less than 40 miles of driving for most electric vehicles), then you need a battery bank large enough to store more than twice that. This is because you can't discharge most deep cycle batteries below 50%, and you're going to have charging efficiency losses with both the inverter and the car charger. With roughly 80% efficiency after these losses (90% efficiency for the car charger, 90% for the inverter plus related losses like wire), you'd need at least 1.25 x 10 = 12.5 kWh of capacity x 2 (50% discharge, max) = a minimum of 25 kWh battery capacity. At 48 volts, that's a 520 ah battery bank, minimum. At 546 AH each, eight of these would be just over the minimum. $861 x 8 = $6888, before shipping, which would also be expensive. You can buy a lot of electricity from the grid for that. And you'd still have to buy the expensive charge controllers (which are not needed with a grid-tie system).

jcheil

Re: Wind-Solar Hybrid for Car-Charging Applications

BB. wrote: »

In California, it is "illegal" for me to install an off grid power system and leave the grid without paying fees to the utility for "stranding their assets"

That is...amazing.

BB.

Re: Wind-Solar Hybrid for Car-Charging Applications

Yep, as power costs increased, companies (especially in agricultural areas--I.e., burning nut husks) were installing co-generation systems and utilities were losing lots of loads--Which killed their return on investments for distribution lines and generation.

Installing Grid Tied Solar was actually an "exception" written into the regulations to allow installation without paying fees for stranding utility investments.

-Bill

ggunn

Re: Wind-Solar Hybrid for Car-Charging Applications

bikiranguha wrote: »

Well, can you show me how a standalone system can cost 4x more than a grid connected one?

With one word - batteries.

bikiranguha

Re: Wind-Solar Hybrid for Car-Charging Applications

BB. wrote: »

Grid connections are "dirt cheap"... Solar panels+GT inverter plus racking turnkey installed--Around $3-$5 per Watt. Just a branch circuit to your existing main panel (assuming panel is large enough to support desired solar array).

Price out an off grid system, adding a battery bank, replacement of the battery bank every 3-10 years, and that a GT system is rough 77% efficient (AC panel ST rating to usable AC Watts to grid), vs Off Grid system which is around 52% efficient for Panel STC Rating to Usable AC power out.

And--you can only store around 1-3 days of sun with an Off Grid system, vs you can "store power" for up to one year with a Grid Tied system (i.e., I generate way more power than I use in the summer, and a draw on that "bank" in the winter--In fact, I draw a negative amount in my "bank" during winter and refill it the next summer (my "true up" period is October to September). You cannot do that with a battery bank.

So, overall, you need about 2x the solar array for an off grid system of equivalent power, and battery bank+cabling+breakers+OG Inverter+Backup Generator+Fuel (if you need emergency backup power). And all the extra maintenance.

If you wish, give us a location (so we can estimate hours of sun) and how many kWH per day you need for vehicle charging--And we can run some quick numbers and see what we get.

I am not trying to argue from authority--I am just saying that is what I/we have, generally, seen when we "run the numbers". It is possible to do better with Off Grid Power if you are willing to accept limitations (1 day of power storage, deeper cycling of battery bank, no backup genset/power source, etc.).

And at the same time not every state/utility charges/treats solar power the same way for Grid Tied. In California, it is "illegal" for me to install an off grid power system and leave the grid without paying fees to the utility for "stranding their assets" (basically the 20-40 year "investments" that my property has been used to back revenue bonds/investments.

It is an interesting project to do a paper design.

-Bill

Thanks for all your help. I intended to know about the topic because I am doing a mock thesis on the feasibility topic on hybrid renewable energy systems. Got some interesting points here.
By the way, Bill, currently I am in Statesboro, Georgia. You are free to "run your numbers", and tell me what you got.

BB.

Re: Wind-Solar Hybrid for Car-Charging Applications

I will "help" you to run the numbers.

First, you need to tell me how many kWH per day you need. Any seasonal variations in power usage (i.e., drive more in summer, less in winter). Also, Are you going to charge the EV during the day, or charge the EV at night? How many days of "storage" do you want in the battery bank (typically, a balanced system is 2 days of storage and 50% maximum discharge--1-3 days of storage is about the "practicable" range of storage for lead acid battery bank).

It would also be helpful to know the Maximum Power draw and AC voltage by the EV charging system (120 VAC systems may draw 12 amps maximum, 240 VAC systems may draw much more). High voltage chargers typically recharge the EV much faster.

-Bill