Hydro/Solar Power CombinedSet Up

Cathalsiew · August 2014

Hi There,

I am new to this game, and I was wondering if anyone can help me with some of the following:

1. I am designing a micro hydro scheme( I am a civil engineer so the hydraulics etc is no problem for me, just the electrical side of things is a bit tougher) which will need to run concurrently with a PV solar system. Can I get suitable advice here(its more in relation to the electrical and battery side of things than the hydro itself)?

If the answer is yes, I have the following details about the scheme I wish to set up.

2. The turbine will produce 500 Watts or 0.5kw per hour. It will be a 24 hour operation; therefore producing 12kWh per day.

3. The peak demand from the house is going to be 4.61kW; and the overall use for a full day will be 44.5kw (which allows for 50% effeciency losses). Knowing this I am going to have to supplement my hydro supply with a PV installation.

Can anyone give me advise on how to run the two systems together?

4.I want to have a couple of days redundancy in my design, so based on a 2 day storage, I need the batteries that can hold 1890ampH's. The voltage of the hydro system will be 48V to reduce losses from the turbine to the battery bank. therefore the current from the turbine will be 13.4 Amp.

So really where i am at, is seeing if this type of design is

a) Feasible(See attached spreadsheet for loadings)
Attachment not found.
b) The size an type of batteries I need(is this possible) Thinking of 4 12V 500ampH strings running in series/parallel.
c) What controllers/chargers are needed for the combined solar and hydro systems

Any other general points or hints would be appreciated

stephendv · August 2014

Re: Hydro/Solar Power CombinedSet Up

A few quick comments. I think your daily usage is skewed, are you really going to run a 4kW dryer every single day? Cutting that down to once every 3 or 4 days will have a massive impact on your usage. Same goes for the cooker and washing machine.
Have you considered using gas for cooking and water heating?
3 x TVs all of them for 12 hours a day? Is that really the case- might be overestimated?
The fridge too is overrated, can you get any kWh/day or kWh/year ratings from the manufacturer? this will give you a more accurate number than the 400 x 24 which is WAY too high.

100W lights must be those incandescent types my great grandfather used during the first world war <joke> These days there are LED or CFLs at a fraction of the rating.
Do you really need that 300W computer? Once you factor in the cost of the batteries and solar PV needed to power it, it may be more cost effective to sell it and buy a more efficient laptop, with under 100W draw at full tilt.

Cariboocoot · August 2014

Re: Hydro/Solar Power CombinedSet Up

Welcome to the forum.

I agree with Stephen; your usage figures don't look accurate. A refrigerator, for example, tends to have a running Wattage of <200 and consumes only about 1 kW hour per day +/- a bit.

Don't guess, measure.

Buy a Kill-A-Watt meter and measure actual power consumption of what you intend to run (or similar devices) under normal usage conditions.

Your 39kW hours per day total is about 50% higher than a typical household.

It is important to get this right because it makes a huge difference in sizing the system.

You can certainly use hydro with solar: two sources charging one bank is not a problem. Both will be regulated. How they are regulated depends on the final system design which depends on the amount of power supplied. Frankly, with 12 kW hours available from hydro you may not need any solar panels. You'd be amazed just how much power that is.

BB. · August 2014

Re: Hydro/Solar Power CombinedSet Up

I agree--Your daily power usage is not an accurate estimate--And conservation will be your friend here.

Also, it is not kW per hour--It is just kWatts. Watts is already a rate and Watt*Hours is the amount of energy (used in a day, etc.).

And you are going to find that many appliances are sized for the "unlimited" power from the Utility Grid.

A North American Energy Start rated refrigerator may use, roughly 600-1,000 VA starting the compressor, ~120 Watts running (at 30-50% duty cycle @ 25C room temperature), and upwards of ~600 Watts peak to run the defrost heaters. A typically full sized N. American efficient refrigerator will use around 1-2 kWatt*Hours per day.

The TV's--Look at the new flat screen LED units... The will use 1/5th to 1/10th the amount of power as models from even a few years ago.

Cooking--that is going to be a big question mark here... If you like soups and stews--Many Asians use a large thermos (we can buy them in local Asian markets here--Not cheap)--Bring the contents to a boil, then put the whole pot in the thermos to set for 4 hours or so--Saves lots of energy.

http://www.thermoscooking.com/
http://www.amazon.com/Get-Prepared-Stuff-Thermal-Cooker/lm/R2JDIMG62OQFDL

Other heating/cooking appliances may have heavy power usage (like a microwave) -- But not too bad on energy used (high power for 10 minutes per meal). Still can be stressful on a battery bank (need larger battery bank for peak current, not average energy usage per day).

If there is anyway you can get rid of the electric drier (propane, line drying, etc.)--Would be a big help. Also, outside of the US, "Water Extractors" (high speed spin basket) are more popular (where energy costs are higher) can remove more water from clothes prior to drying (save energy--but can stretch/damage fine clothes due to high "G" force).

http://www.amazon.com/The-Laundry-Alternative-Nina-Dryer/dp/B00CDWTQKI

For the Washing Machine, it looks like that is a very high peak load--Are you looking at ones that have electric water heaters inside?

I believe you are out of New Zealand--I have a very nice Fisher Paykel washer that used a DC motor to run the tub--uses 1/5th the peak wattage and is not bad on overall power usage either (~250 WH per wash).

Lights--Go with CFL or LED... Much more expensive up front--But use 1/5th the amount of power (try LED--You probably will be happier with them vs CFL).

Computer--anyway you can live with a laptop? They use about 30 Watts vs the 200-300 for a large desktop machine.

The water pump--Have you picked your yet? Many standard AC pumps will draw much more than 600 Watts. There are "off grid friendly" water pumps with much lower surge current (600 Watts possible) and more efficient at pumping. 5 hours of pumping per day seems like a lot of water.

Anyway--If you were living a very conservative off grid home:

1 kWH per day -> Lights, Radio, Laptop Computer, small water/well pump
3.3 kWH per day -> Add a full sized refrigerator and clothes washing machine
10 kWH per day -> Add teens, more computers, TVs, central heat, etc.
33 kWH per day -> Some A/C and electric cooking (average north American home electricity usage (~1,000 kWH per month)
100 kWH per day -> Lots of A/C and Electric Heat (Florida or Texas)

One thing you did not mention is hot water--With the advent of heat pumps--In reasonably warm climates people are running "electric water heaters" on relatively small off grid power systems. A heat pump water heater is ~2-3x as efficient as resistance based heater. Similar with heat pump space heating--A few people are using mini-split heat pump systems for off grid use... On less than 10kWH per day (I believe).

And regarding your battery sizing... 2 days of storage is fine (1-3 days is usually a "workable" range)--But we also, for lead acid batteries, recommend a maximum discharge to 50% state of charge for longer battery life (and buffer as battery ages/and for emergencies). So--Your battery AH rating would be ~4x your daily power usage.

Regarding parallel strings of batteries--I would get as large of AH cells as you can manage (move at your location)--Those may be 6 volt, 4 volt, or even 2 volt cells wired in series. Personally, I like to recommend 1 string if possible. 2-3 strings is also OK (some people like 2 strings--They can cut back to one string as backup if a cell/battery fails). Current sharing among parallel strings can be an issue. And maintaining all of those battery cells is a pain--As well as the costs/issues of wiring up parallel strings.

Regarding charge controllers--A relatively new thing to do is put a MPPT charge controller between the Hydro (or Wind) Turbine Alternator and Battery Bank. It lets you run your alternator at a higher output voltage (more efficient and less current--smaller diameter wiring).

Down side is that you may need to manage turbine over-speed/shut down if the MPPT controller fails (many turbines will over-speed if their electrical load is dropped during normal operation--Need to shut down water, short the output, put a resistor bank, etc. on the output to limit maximum RPM).

In the end, energy usage is a highly personal set of choices. Conservation is usually your first/best investment of limited funds as it is almost always cheaper to conserve power than to generate it.

-Bill

zoneblue · August 2014

Re: Hydro/Solar Power CombinedSet Up

Cathalsiew wrote: »

I am designing a micro hydro scheme

If you have a high head reliable low flow, then thats a real coo. High flow, flood prone rivers are your nemesis there. Certainly take a look at the Powerspout line.

The turbine will produce 500 Watts or 0.5kw per hour. It will be a 24 hour operation; therefore producing 12kWh per day.

500W constant, 12kWh/day. Do you have a summer dry up with that? That will dictate the solar side of it. Otherwise take the 12kWh, add enough storage to support the inverter you want and laugh all the way to the big screen.

The peak demand from the house is going to be 4.61kW; and the overall use for a full day will be 44.5kw

Youve got the right general idea on the load budget, but your numbers are in excess of a whole order of magnitude too high. Example:

Item	No	Watts	Duty	Hours	Usage
----------------------------------------------
Fridge	1	100	0.4	24	960
Washer	1	900	0.3	1	270

I want to have a couple of days redundancy in my design, so based on a 2 day storage, I need the batteries that can hold 1890ampH's.

With hydro you dont need days storage unless you have intake blockage or other reliability issues.

The voltage of the hydro system will be 48V to reduce losses from the turbine to the battery bank. therefore the current from the turbine will be 13.4 Amp.

The powerspout range come in a range of voltages, but if you have any distance the 100+ AC works well, as you can step it down and rectify it at the end of the line.

The size an type of batteries I need(is this possible) Thinking of 4 12V 500ampH strings running in series/parallel.

The challenge with hydro is that you primarily need storage to support/buffer the inverter more than anythng else. Generation is constant right, so generally we use a figure of 100Ah of battery per kW of inverter. Then youd need to look at your daily usage pattern. Are there severe peak periods, how long, how much kWh. These factors will drive your bank size. Without large loads or peak periods you can conceivably get away with a small bank, but then you hit the charge rate issue. Batterys like about 10% of the C rating as a bulk charge rate. However with hydro ive seen this rule broken a lot.

What controllers/chargers are needed for the combined solar and hydro systems

I suggest you fix the load budget first, then well see. Youll need a diversion system, or a controller capable of handling the peak open circuit voltage of the turbine. Midnite classic 200s are common with Powerspouts for the simple reason that they can handle a free spinning powerspout without diversion.

Cathalsiew · August 2014

Re: Hydro/Solar Power CombinedSet Up

stephendv wrote: »

A few quick comments. I think your daily usage is skewed, are you really going to run a 4kW dryer every single day? Cutting that down to once every 3 or 4 days will have a massive impact on your usage. Same goes for the cooker and washing machine.
Have you considered using gas for cooking and water heating?
3 x TVs all of them for 12 hours a day? Is that really the case- might be overestimated?
The fridge too is overrated, can you get any kWh/day or kWh/year ratings from the manufacturer? this will give you a more accurate number than the 400 x 24 which is WAY too high.

100W lights must be those incandescent types my great grandfather used during the first world war <joke> These days there are LED or CFLs at a fraction of the rating.
Do you really need that 300W computer? Once you factor in the cost of the batteries and solar PV needed to power it, it may be more cost effective to sell it and buy a more efficient laptop, with under 100W draw at full tilt.

Thanks everyone for your input so far! Been very helpful.

I have updated my consumption estimation see below.

Attachment not found.

I think this is a more realistic estimation of consumption. The client is not very forthcoming with usage information*even though it will be of ultimate benefit to him)

Cathalsiew · August 2014

Re: Hydro/Solar Power CombinedSet Up

Attachment not found.

Apologies....attachment above:grr

Cathalsiew · August 2014

Re: Hydro/Solar Power CombinedSet Up

Cariboocoot wrote: »

Welcome to the forum.

You can certainly use hydro with solar: two sources charging one bank is not a problem. Both will be regulated. How they are regulated depends on the final system design which depends on the amount of power supplied. Frankly, with 12 kW hours available from hydro you may not need any solar panels. You'd be amazed just how much power that is.

Thanks for your feedback. So in terms of the dual sources(if I still need them with my reduced consumption figures) so I need a seperate (MTTP) controller for each, or would just one be sufficient?

stephendv · August 2014

Re: Hydro/Solar Power CombinedSet Up

Cathalsiew wrote: »

Thanks for your feedback. So in terms of the dual sources(if I still need them with my reduced consumption figures) so I need a seperate (MTTP) controller for each, or would just one be sufficient?

Those numbers look much better, and I suspect that the cooker usage of 6kWh/day (the same as what our entire house uses in a day) will also be much lower in practice. You'll need 2 separate controllers for the hydro and for the PV.
Since the usage is very close to what the estimated production of the hydro is, on it's own, you could just first install the hydro with controller and see how it goes. Then install solar PV + controller if there's a shortfall. There's no advantage to installing them both at the same time. Much better to see the energy numbers in actual use rather than guestimate, especially when the numbers are so unclear.

Cathalsiew · August 2014

Re: Hydro/Solar Power CombinedSet Up

Anyway--If you were living a very conservative off grid home:

1 kWH per day -> Lights, Radio, Laptop Computer, small water/well pump
3.3 kWH per day -> Add a full sized refrigerator and clothes washing machine
10 kWH per day -> Add teens, more computers, TVs, central heat, etc.
33 kWH per day -> Some A/C and electric cooking (average north American home electricity usage (~1,000 kWH per month)
100 kWH per day -> Lots of A/C and Electric Heat (Florida or Texas)

Looks like my revised consumptions are more in line with this.

One thing you did not mention is hot water--With the advent of heat pumps--In reasonably warm climates people are running "electric water heaters" on relatively small off grid power systems. A heat pump water heater is ~2-3x as efficient as resistance based heater. Similar with heat pump space heating--A few people are using mini-split heat pump systems for off grid use... On less than 10kWH per day (I believe).

Hot Water will be generated using "wet-back" ---hot water cylinder heated directly from open fire.

And regarding your battery sizing... 2 days of storage is fine (1-3 days is usually a "workable" range)--But we also, for lead acid batteries, recommend a maximum discharge to 50% state of charge for longer battery life (and buffer as battery ages/and for emergencies). So--Your battery AH rating would be ~4x your daily power usage.

In terms of the maximum discharge of state of charge. If my daily AH usage was 406 AH; would I need a 812AH battery pack to ensure that I would not be discharging more than 50%. And if that is the case, and I wanted to ensure I had two days supply(800AH's Approx) would the 812AH pack still be sufficient?

Regarding parallel strings of batteries--I would get as large of AH cells as you can manage (move at your location)--Those may be 6 volt, 4 volt, or even 2 volt cells wired in series. Personally, I like to recommend 1 string if possible. 2-3 strings is also OK (some people like 2 strings--They can cut back to one string as backup if a cell/battery fails). Current sharing among parallel strings can be an issue. And maintaining all of those battery cells is a pain--As well as the costs/issues of wiring up parallel strings.

Looking at my figures I think I will need a 48V 810AH pack. Can you recommend any places in NZ that would be able to supply this as one battery, or possibly in a way that I could have just one string in series?

Regarding charge controllers--A relatively new thing to do is put a MPPT charge controller between the Hydro (or Wind) Turbine Alternator and Battery Bank. It lets you run your alternator at a higher output voltage (more efficient and less current--smaller diameter wiring).

Down side is that you may need to manage turbine over-speed/shut down if the MPPT controller fails (many turbines will over-speed if their electrical load is dropped during normal operation--Need to shut down water, short the output, put a resistor bank, etc. on the output to limit maximum RPM).

Can one MPPT controller be used to control a Solar and Hydro system running concurrently? Does having a MPPT negate the need to having a diversion load or somewhere to discharge excess power?

Cathalsiew · August 2014

Re: Hydro/Solar Power CombinedSet Up

If you have a high head reliable low flow, then thats a real coo. High flow, flood prone rivers are your nemesis there. Certainly take a look at the Powerspout line.

I have 20l/s at 9m head, and sufficient room to house turbine out of flood plains thankfully! Have you had experience with Powerspout? I have that as one of my 3 options for turbines, howver someone told me that they are more aligned for "hobbyiests" as they required a lot more maintanence than others on the market

500W constant, 12kWh/day. Do you have a summer dry up with that? That will dictate the solar side of it. Otherwise take the 12kWh, add enough storage to support the inverter you want and laugh all the way to the big screen.

Yes that is the low(summer) power output.(will limit the inflow to this amount. Can you explain the storage in relation to the inverter side of things? I thought that if my peak load was say, 3.8kW; then a 4.5kW intervor would be sufficient. I didnt think there was a need for extrage storage for the inverter?

Youve got the right general idea on the load budget, but your numbers are in excess of a whole order of magnitude too high. Example:
Item	No	Watts	Duty	Hours	Usage
----------------------------------------------
Fridge	1	100	0.4	24	960
Washer	1	900	0.3	1	270

Thanks I have updated my consumption to relate to this advise. My client will have to look at energy saving appliances as part of my design.

With hydro you dont need days storage unless you have intake blockage or other reliability issues.

I think allowing 2 days storage as factor of satey for the whole system in this case is acceptable.

The powerspout range come in a range of voltages, but if you have any distance the 100+ AC works well, as you can step it down and rectify it at the end of the line.

My understanding is that the Powerspout produces AC, then converts to DC at the turbine? Is that not the case. I know they have a TRG56, which produces a 48V wattage(not sure if that is the correct term!):p

The challenge with hydro is that you primarily need storage to support/buffer the inverter more than anythng else.

Im sorry I do not really understand this principle as yet, can you give me a bit more detail?

Generation is constant right, so generally we use a figure of 100Ah of battery per kW of inverter.

So if I have a 4.5kW Inverter, are you saying that a 450AH battery system would be sufficient? This doesn't make sense to me as my 2days usage will be Approx 800AH?. Apologies in advance if these are nvice questions.

Then youd need to look at your daily usage pattern. Are there severe peak periods, how long, how much kWh.

I have worked on a peak loading of 3.9kW........

These factors will drive your bank size. Without large loads or peak periods you can conceivably get away with a small bank, but then you hit the charge rate issue. Batterys like about 10% of the C rating as a bulk charge rate

.

Can you explain this one a bit more to me?

I suggest you fix the load budget first, then well see.

Done See my attached Rev 2 of power consumption

Youll need a diversion system, or a controller capable of handling the peak open circuit voltage of the turbine.

Is there any easy way of calculating the VOC of a turbine? I have initially sized my controller based on the max current( using P=VI) which works out to be 13amps for my 48V system.

Midnite classic 200s are common with Powerspouts for the simple reason that they can handle a free spinning powerspout without diversion.

Again your thoughts on Powerspout and possible other options would be appreciated here as I have had mixed reports on all of them!

On question I have is( I am based in NZ), would you have any thoughts on a good supplier of batteries here?

Thanks in advance!!!!

Cathalsiew · August 2014

Re: Hydro/Solar Power CombinedSet Up

stephendv wrote: »

Those numbers look much better, and I suspect that the cooker usage of 6kWh/day (the same as what our entire house uses in a day) will also be much lower in practice. You'll need 2 separate controllers for the hydro and for the PV.
Since the usage is very close to what the estimated production of the hydro is, on it's own, you could just first install the hydro with controller and see how it goes. Then install solar PV + controller if there's a shortfall. There's no advantage to installing them both at the same time. Much better to see the energy numbers in actual use rather than guestimate, especially when the numbers are so unclear.

Great, so my understanding is that to size the contoller, I use the power formula, P=VI, which in my case works out to be 13AMPS for a 48V turbine generator and 48V battery pack.

If I am using a 48V battery pack for the hydro, what do solar panel generally produce voltagewise?.....would I look for a 48V solar system(or does this even exist) or is the voltage convertage at the controller before it charges the batteries?

Cheers

stephendv · August 2014

Re: Hydro/Solar Power CombinedSet Up

Cathalsiew wrote: »

Great, so my understanding is that to size the contoller, I use the power formula, P=VI, which in my case works out to be 13AMPS for a 48V turbine generator and 48V battery pack.

Yes, except that the current limit on the controller refers to the output, not the input. MPPT type controllers can usually accept a higher input voltage and then down convert that to the battery voltage. This can help reduce losses if the hydro turbine is far away from the batteries, so you can use a turbine that produces 100V send that across the cables to the MPPT controller, which will then convert that to 48V.

Cathalsiew wrote: »

If I am using a 48V battery pack for the hydro, what do solar panel generally produce voltagewise?.....would I look for a 48V solar system(or does this even exist) or is the voltage convertage at the controller before it charges the batteries?

If you're using a PWM controller and a 48V battery then you need 2 panels in series with a Vmp rating of around 36V each = 72V in total. Then you'd build the array by putting these groups of two in parallel. Panels with Vmp of around 18V or 36V are usually specific for off-grid applications because they can be used to charge a 12v and 24v battery with a cheap pwm controller.

If you're using an MPPT controller then the input voltage from the PV should be above 70V and below the limit of the controller, usually 140V for most MPPT controllers. Your best bet in this scenario is to use groups of 3 x 30Vmp panels in series. Panels with a Vmp of 30V are commonly used for grid tie applications and there are a huge number of them in the market, which usually means they're cheaper than using the "off-grid" panels with 36Vmp.

So basically your two options are: PWM with a cheap controller + more expensive panels; or MPPT with a more expensive controller but cheaper panels and better efficiency. Which is better will depend on your local prices for the kit and the distance between the PV and the batteries, longer distance means thicker wire with PWM and would favour using MPPT and a higher panel voltage.

zoneblue · August 2014

Re: Hydro/Solar Power CombinedSet Up

Cathalsiew wrote: »

I have 20l/s at 9m head, and sufficient room to house turbine out of flood plains thankfully! Have you had experience with Powerspout? I have that as one of my 3 options for turbines, howver someone told me that they are more aligned for "hobbyiests" as they required a lot more maintanence than others on the market

All the maintenance in hydro is in intake clearance. Bit of grease from time to time. There are at least a dozen powerspouts running within 20kms of here, and have been for many years. They are time tested. The hard part is getting hold of him.

Can you explain the storage in relation to the inverter side of things? I thought that if my peak load was say, 3.8kW; then a 4.5kW intervor would be sufficient. I didnt think there was a need for extrage storage for the inverter?

The concept of days storage is an older one, that gets less relevent today. Batterys are now the most expensive component in systems, so you want the minimum you can get away with. For solar we work with 25%DOD daily, that gives you a second day without sun down to 50% DOD. That coincides with the peak cycle life of most cells. With hydro you dont need to factor days without per se. What you do need is enough to buffer your load peaks, your load variation, and enough to support the inverter. An inverter will not run well with less than 100Ah per kW of inverter. Thats about the ability to deliver surge. So dont go lower than that is all im saying there.

My client will have to look at energy saving appliances as part of my design.

Client huh. Do we get a cut

My understanding is that the Powerspout produces AC, then converts to DC at the turbine? Is that not the case. I know they have a TRG56, which produces a 48V wattage(not sure if that is the correct term!):p

You can put the rectifier anywhere you want. One system up the road has 1 full km of cable from the turbine to the battery. Michael can wind the smartdrives in many diff configurations depedning on your need.

So if I have a 4.5kW Inverter, are you saying that a 450AH battery system would be sufficient? This doesn't make sense to me as my 2days usage will be Approx 800AH?. Apologies in advance if these are nvice questions.
I have worked on a peak loading of 3.9kW........
Can you explain this one a bit more to me?

Peak load is one thing. But its the way that the kWhrs bunch up or dont in your load profile, that will determine how much storage you need. Imagine your load profile is flat, each hour of the day you use 1/24 of your demand. Then all you need is a single hours storage, AND enough to support the inverter. If on the other hand you have a big load spike at 6-8pm that comprises 1/4 of your demand then you need enough storage to support that. Remember that you (mostly) cant solve problems in RE by doing what engineers often do, double then double again for luck. With hydro you dont have the charge rate to support big banks. So with batterys its all about getting the optimum size, and that comes down to modelling your load profile across the day, week, year whatever. Another reason not to oversize the bank is that lightly cycling the bank is also not good for it (grid corosion).

Having said this, 800Ah at 48V isnt an unreasonable sized bank. But just to give you an idea it will take 3-4kWp of solar to support it. To get that magical 10% charge rate.

Is there any easy way of calculating the VOC of a turbine? I have initially sized my controller based on the max current( using P=VI) which works out to be 13amps for my 48V system.

Youll have to get that from the specs. Diversion systems are bit of pain. The smallest problem with themm one corroded connection, and your bank is toast. However they have been used for years, and work ok. One obvious system is to heat water, but with a long steady trickle of amps youd need to size the element carefully, or use PWM tpye systems.

On question I have is( I am based in NZ), would you have any thoughts on a good supplier of batteries here?

When i was shopping the most readily available are the crown line. 6v flooded cells. They are affordable. If you want top of the line look at hoppecke (sp?) which also has a distributer here. For AGMs AA solar sell a line, also a line of LiFePo4. Both pricey.

Batterys are a pain. Telecom still unloads various phone exchange office backup banks, these vary from agm to flooded. The latter can be found in systems around here, some are an incredible 30 years old. Yes really. They can be had for little if you are in the right place at the right time. Theres a guy in timaru that imports the Toyos that we have. Hard to say what the quality is like, theyre chinese. Pretty cheap.

But your still looking at 10K+ for a 40kWh bank, no matter how you spin it. Then replace it every decade (or less). In most places the daily line charge from the grid is cheaper than that! Thats why we try to get the bank size down....

inetdog · August 2014

Re: Hydro/Solar Power CombinedSet Up

zoneblue wrote: »

Batterys are a pain. Telecom still unloads various phone exchange office backup banks, these vary from agm to flooded. The latter can be found in systems around here, some are an incredible 30 years old. Yes really. They can be had for little if you are in the right place at the right time. Theres a guy in timaru that imports the Toyos that we have. Hard to say what the quality is like, theyre chinese. Pretty cheap.

Those Telco application batteries are designed for constant float service, with drawdown in case of power outage happening maybe once or twice a year. They are not designed for regular cycle use and will fail much earlier in that application. Similar in that respect to typical UPS batteries.
Now the battery bank for an off grid cell tower that uses solar and generator power all the time will be a different type of battery entirely, and if you can get some of those which have been routinely replaced it may be a better deal.

zoneblue · August 2014

Re: Hydro/Solar Power CombinedSet Up

Realise that those arent your average cell. They are huge 2v cells in see through tough plastic cases. I doubt they have anywhere near their spec capacity, but i know two seperate RE systems using them, and have been for 10+ years. Ill try to get some photos and specs when im there next. They dont make em like that they used to i guess.

stephendv · August 2014

Re: Hydro/Solar Power CombinedSet Up

zoneblue wrote: »

Realise that those arent your average cell. They are huge 2v cells in see through tough plastic cases.

On this side of the ponds those sound like the OPzS flooded cells used for float and deep cycle service in telecom and large off-grid install. Most of the big name batt manufacturers make them and they're similar in construction to forklift cells (tubular plates) with some differences:
- self supporting transparent container
- Much more space above the plates for electrolyte, usually meaning you need to water them once a year in deep cycle applications
- lower SG, usually 1.24

An example: http://www.hoppecke.com/products/batteries-sorted-by-applications/renewable-energy/opzs-solarpower/

Cathalsiew · August 2014

Re: Hydro/Solar Power CombinedSet Up

OK Thanks again for all your comments......Been really helpful.

When I said client earlier on, its really a mate of mine that I'm helping out, that said he would shout me a few beers or two if it worked lol!

So to summarise the discussion below, these are my thoughts

1) Based on my new loadings and looking at just 1 day of autonomy in terms of the battery capacity, I will need a 48V pack with 1354AHS capacity. This will result in a a DOD of 30% for the battery pack(without looking at the loading distribution during the day)

So I should use a quality MPPT to charge the batteries is this correct? My peak amperage from the Hydro will be 10.5Amps at 48V. Can anyone recommend a suitable MMPT?

So then I also need a suitable sized inverter for my Peak Load(in this case 4.7kW). Can a MMPT be a charger/controller/inverter all in one?

Going back to my batteries; taking for example a fully charged batter at 12:00am; with a micro hydro producing 500Wh's, can anyone tell me a way to work out the charging distribution during the day? I have a spreasheet set up to complete this, but unsure as to how to work of the rate of charging(and should I have a limit on how fast I charge the batteries?)

Again cheers in advance

BB. · August 2014

Re: Hydro/Solar Power CombinedSet Up

Cathalsiew wrote: »

So I should use a quality MPPT to charge the batteries is this correct? My peak amperage from the Hydro will be 10.5Amps at 48V. Can anyone recommend a suitable MMPT?

One of the questions with any turbine (wind or water) is what happens if the DC load "goes away" (charge controller or battery bank fuse blows or charge controller decides no more energy is needed). How high of voltage and RPM will the turbine reach. Will the turbine self destruct or will the unloaded turbine voltage blow out the MPPT charge controller.

From the charge controller's point of view, it would be best to pick a controller that would not be damaged by an over-speed. The Midnite family (Kid, Classic) have pretty high Vin ratings (and there are Classics with even higher input voltage ratings).

So then I also need a suitable sized inverter for my Peak Load(in this case 4.7kW). Can a MMPT be a charger/controller/inverter all in one?

There may be a few out of China--But putting everything into one box is always a risk. If one section fails, then you have to take everything out of service and get repaired/replaced.

The only reason an inverter/charger combination (AC battery charging + DC to AC inverter) makes sense is because the major components can do either inverting or charging--So you are saving money/space by having the same components do two tasks.

An MPPT controller in the same box--There is not many (if any shared components) that can do both MPPT charging and inverter/charger functions. So any all-in-one unit would not seem to offer much in the way of savings of costs or complexity.

Going back to my batteries; taking for example a fully charged batter at 12:00am; with a micro hydro producing 500Wh's, can anyone tell me a way to work out the charging distribution during the day? I have a spreasheet set up to complete this, but unsure as to how to work of the rate of charging(and should I have a limit on how fast I charge the batteries?)

For Lead Acid Batteries, they generally want ~5% to 13% rate of charge. If you have constant loads during the day/charging time (water pumping, office lighting/computers/etc.), you could size the charging capacity as:

5-13% rate of charge + steady state loads = Total "charging" source Wattage.

-Bill

zoneblue · August 2014

Re: Hydro/Solar Power CombinedSet Up

Cathalsiew wrote: »

1) Based on my new loadings and looking at just 1 day of autonomy in terms of the battery capacity, I will need a 48V pack with 1354AHS capacity.

Still sounds kinda big. 65kWh bank, cost around 15K+. Are you sure you need that much? Its a rare RE system that does.

Going back to my batteries; taking for example a fully charged batter at 12:00am; with a micro hydro producing 500Wh's, can anyone tell me a way to work out the charging distribution during the day? I have a spreasheet set up to complete this, but unsure as to how to work of the rate of charging(and should I have a limit on how fast I charge the batteries?)

As i said with hydro its very unlikely you will have to worry about high charge rates. On the contrary with 1500Ah your problem will be getting enough amps. 10% of 1500 is 150A, and your little turbine puts out 10.

For the day time loads its just a matter of putting time of day against your load budget and adding up the ah per hour. With solar we tend to load shift, and do things that we might not ordinarily do during the day... during the day. You tend to adapt. With hydro its obviously in your interest to spread out your loads. I guess if you have any kind of midday peak period solar will help there.

Cathalsiew · August 2014

Re: Hydro/Solar Power CombinedSet Up

BB. wrote: »

One of the questions with any turbine (wind or water) is what happens if the DC load "goes away" (charge controller or battery bank fuse blows or charge controller decides no more energy is needed). How high of voltage and RPM will the turbine reach. Will the turbine self destruct or will the unloaded turbine voltage blow out the MPPT charge controller.

From the charge controller's point of view, it would be best to pick a controller that would not be damaged by an over-speed. The Midnite family (Kid, Classic) have pretty high Vin ratings (and there are Classics with even higher input voltage ratings).

There may be a few out of China--But putting everything into one box is always a risk. If one section fails, then you have to take everything out of service and get repaired/replaced.

The only reason an inverter/charger combination (AC battery charging + DC to AC inverter) makes sense is because the major components can do either inverting or charging--So you are saving money/space by having the same components do two tasks.

An MPPT controller in the same box--There is not many (if any shared components) that can do both MPPT charging and inverter/charger functions. So any all-in-one unit would not seem to offer much in the way of savings of costs or complexity.

For Lead Acid Batteries, they generally want ~5% to 13% rate of charge. If you have constant loads during the day/charging time (water pumping, office lighting/computers/etc.), you could size the charging capacity as:

5-13% rate of charge + steady state loads = Total "charging" source Wattage.

-Bill

Excuse my ignorance here; but i am a little confused still. So my battery pack will be say 1300 Ahs; and say roughly 1kwh at 48V = 200Ahs of constant loads so does my rate of charge need to be say (130ish + 200= 330amps)?? And if so can this be regulated by the controller?? or the charger inverter......so if these are dumb questions

I have also attached what I think is how my system is set up?? Is this correct in my assessment??Attachment not found.

Cariboocoot · August 2014

Re: Hydro/Solar Power CombinedSet Up

It should work like this:

1300 Amp hours with a peak charge current of 130 Amps. Peak current is not sustained current.
If concurrent loads draw 200 Amps then the charge source must be capable of maintaining 330 Amps to achieve the desired peak current. Usually loads are not constant and an allowance for them is factored into the 10% rule-of-thumb (except for batteries which demand that 10% rate, so the peak current spec needs to be increased).
Charge sources are regulated by Voltage for RE systems. They need to be able to supply and regulate under maximum current, which in this example would be 330 Amps (which is beyond the range of any one controller).

Your diagram is essentially correct. The only issue is in the detail of the charge controller for the hydro and how it operates. If it is something like a MidNite Classic & Clipper then there would be a diversion load available to shed excess power to when the batteries are full. Often this is done with a diversion controller attached to the battery as per this Morningstar diagram (Page 2, right): http://www.solar-electric.com/lib/wind-sun/TSdatasheet.pdf

BB. · August 2014

Re: Hydro/Solar Power CombinedSet Up

As Marc/Cariboocoot says...

To clarify units:

1kwh at 48V = 200Ahs of constant loads

The actual math/units would be:

1,000 Watts / 48 volts = 20.8 Amps

So--I am a little confused. Watt*Hours is a measurement of total energy... Like:

120 Watt load * 8 hours = 960 Watt*Hours

Watt is a rate--Like miles per hour
Watt*Hours is an amount--Like miles driven

So--Do you have 1kWH of constant loads over a 24 hour period:

1,000 WH / 24 hours per day = 41.7 Watt average load

Or do you have a 1,000 Watt load * 24 hours per day:

1,000 Watts * 24 hours = 24,000 WH = 24 kWH per day

You will vary different answers depending on exactly what you actually intended to say.

-Bill

zoneblue · September 2014

Re: Hydro/Solar Power CombinedSet Up

What im thinking is that you need some help. Get a hydro installer in and do it right. Theres a surprising amount of traps for new players in RE. My electrical engineering background was insufficient in my case, and we made quite a few mistakes. But it was a small system and hence they didnt cost us too much. Youre speccing out a 30K+ system, and your mistakes arent going to do your mate any favors.

Cathalsiew · October 2014

Re: Hydro/Solar Power CombinedSet Up

Thanks Guys for all your input. I am going to go with a Powerspout option, and go through the detail with Michael.

Thanks BB, I am looking back at my post and trying to figure out what I was trying to say also! If I am using 19.3kWh per day; my calculations come up with needing a 406Amph Battery pack.

And based on a max 30% DOD, I have come up with the 1348Amph Batterty pack? Is my logic not correct?

Cheers

Cariboocoot · October 2014

Re: Hydro/Solar Power CombinedSet Up

Pretty close.

19.3 kW hours AC will be more like 23 kW hours DC due to conversion efficiency and inverter consumption. On 48 Volts that will be around 480 Amp hours used. If that amount represents 30% of the battery bank then the total size is 1600 Amp hours @ 48 Volts.

Note there are some fudge factors in that some of the daily load will be supplied 'directly' by PV (or other charge source) when the batteries are full and there is some Watt hour capacity available between the minimum/nominal 48 Volts and the fully charged 51-52 Volts even without the charging source(s).

Hydro/Solar Power CombinedSet Up

Comments

Categories