Need help finding someone to design my off grid solar/hydro hybrid

BobAG

We are building an off grid cabin and need help with the design of our power source. We have a water source we can get about 1/2 of our power from using hydro and would like to do the rest with solar. I have been able to find solar design and hydro design websites , but I need to combine the two in one system. Any suggestions where I can find help?

Thanks,
Bob

BB.

How large of system (Watt*Hours per day, AH @ XX volt battery bank, etc.) and where (roughly) will the system be located...

Personally, I am not in the solar business but there are others here that are.

For a smaller system (say 3,300 WH per day, 800 AH @ 24 volt or less) system--You may be able to do most of the engineering yourself...

For larger systems--Yes, having an experienced designer/installer is a big help towards a successful system.

In theory, you can parallel two (or more) charging sources to one battery bank...

For solar panels, that is easy... The solar charge controller manages the battery bank (more or less) by cycling the solar panels on/off as needed.

For Hydro power--More complicated. Generally, hydro is manually controlled to supply a constant current to the battery bank. And you use a "dump" controller to simply send any "excess charging current" to a load bank (power resistors) to prevent the battery bank from over charging.

For larger systems, and better optimized harvest of hydro power--Other things can be done (more complexity)--It sort of depends on what your needs and expectations are...

-Bill "not an expert" B.

mike95490

reliable hydro needs a very clean and stable water supply, often involving daily inspection of the intake & cleaning the screens
  But it does work in the nighttime

And a special charger and waste (dump) load is needed ( or an electric valve to shut the water off ) when the batteries get full and you don't want to boil them dry
( very expensive)

Marc Kurth

BobAG said:

We are building an off grid cabin and need help with the design of our power source. We have a water source we can get about 1/2 of our power from using hydro and would like to do the rest with solar. I have been able to find solar design and hydro design websites , but I need to combine the two in one system. Any suggestions where I can find help?

Thanks,
Bob

Bob, I am not in the business but I do know people who have designed/built combination hydro and solar projects. Where are you located?

Marc

mike95490

Your first task, is to determine your daily seasonal load requirements.  Microwave Oven, Mini-Split heat pumps, Well Pump, sump pumps, sewage pumps, computers, lighting, TV's phone chargers. 
Spring, Summer, Fall, Winter

BobAG

Hello and thank you for your replies, I will try to answer all your questions here. 
We need a 10KW system. 5KW from solar and 5KW from hydro is what I have calculated.
We are in South east Wyoming near a little town called elk mountain.
the water source is a very clean spring with about 350' of static head. I am getting 14GPM from a 1" line. Yes we have a screen in the line.

 I have taught myself enough about solar and hydro to know I need help with the design.

BB.

What do you mean by 10 kWatt system? 

There is 10 kWatts charging * 5 hours a day by sun or 24 hours a day by hydro...

• 5 kWatt * 5 hours of sun = 25 kWH per day solar = 25,000 Watt*Hours per day
• 5 kWatt * 24 hours of hydro = 120 kWH per day = 120,000 WH per day
• 25 kWH + 120 kWH = 145 kWH per day

And there is 10 kWatt*Hours (10,000 WH) per day... Or something like a 400 Watt load * 24 hours per day

• 400 Watts * 24 hours = 9,600 WH per day

I would guess you mean the second--10 kWH per day or 300 kWH per month...

A 3.3 kWH per day system is a "medium" sized off grid power system (about the minimum needed to run LED Lights, full size refrigerator, washing machine, laptop computer, LED TV...

A 10 kWH per day or 300 kWH per month syatem is a "relatively large" off grid power system and pretty close to the North American average energy usage of 500 kWH per month (using natural gas or propane for heating, cooking, and hot water) to 1,000 kWH per month (electric heat, some A/C, etc.).

Using PV Watts:
https://pvwatts.nrel.gov/pvwatts.php

"PVWatts: Monthly PV Performance Data"

Requested Location: elk mountain Wyoming

Location: Lat, Lon: 41.69, -106.42

Lat (deg N): 41.69

Long (deg W): 106.42

Elev (m): 2216.600098

Array Tilt (deg): 42

Array Azimuth (deg): 180

Month / Solar Radiation (kWh/m^2/day)

1 3.77

2 4.01

3 5.39

4 5.87

5 5.95

6 6.53

7 6.52

8 6.37

9 6.32

10 5.41

11 4.37

12 3.25

Say you want 10 kWH per day from solar and your worst month is December (and use genset as backup--Assume dry winter):

• 10,000 WH per day * 1/0.52 off grid AC system eff * 1/3.25 hours of sun per day (Dec average) = 5,917 Watt solar array December "break even"

A very rough estimate of hydro power of 14 GPM * 350 foot head (ignoring pipe friction, turbine efficiency, and such): 

https://www.calculatoratoz.com/en/hydro-power-calculator/Calc-8270?FormulaId=8270

~3,033 Watts = 3 kWwatt rate of power

• 3,000 Watt * 24 hours per day = 72,000 WH = 72 kWH per day per day of water flow (excluding major losses)
• 5,000 WH per day needed from hydro (?) / 24 hours of hydro per day = 208 Watts from turbine+alternator+charge controller hydro system (24 hours per day * 7 days per week operation)

Or throwing some rough efficiency numbers in:

http://ieomsociety.org/bogota2017/papers/251.pdf

• Component Efficiency
• Canal 95%
• Penstock 90%
• Turbine 60 -80%
• Generator 85%
• 0.95*0.90*0.60*0.85= 39% efficiency (very rough guess)
• 208 Watt electrical requirement * 1/0.39 overall efficiency = 533 Watts of "water power"
• 14 GPM * 1/3,000 Watts of water * 533 Watts of water needed = 2.7 GPM of actual water flow needed (out of 14 GPM spring)

So it seems that you have more than enough Water and height to generate (I guess).

Battery bank... Assuming 10 kWH per day, 2 days of storage, and 50% max planned discharge (a good starting point for Flooded Cell Lead acid battery design rules--And to "buffer" your power sources):

• 10,000 WH per day * 1/0.85 AC inverter eff * 2 days storage * 1/0.50 max discharge * 1/48 volt battery bank = 980 AH @ 48 volt battery bank

For a 10% minimum rate of charge (summer, no hydro, solar power only, full time off grid suggested minimum for FLA battery bank):

• 980 AH battery * 59 volts charging * 1/0.77 solar panel+controller deratings * 0.10 rate of charge = 7,509 Watt array nominal (based on battery bank capacity)
• Somewhere around 5,917 Watt array to 7,509 Watt array suggested minimum for Solar

Anyway--Some initial sizing guesses.... Lots of other questions (how many months a year can you get 2.7+ GPM from water source, what your actual power needs are--10 kWH per day? That is quite a bit of energy for a "cabin".

Lots of fudge factors too... Normally, would suggest that you only use ~50% to 65% of predicted solar harvest for your base loads (those loads you need to run every day like lighting, refrigerator, work tools... And other loads like water pumping for irrigation, washing machine, etc. be put off until sun is shining again)--Allow for daily weather variations, dust on panels, etc... 

A 10,000 WH per day system... That is pretty large for a "cabin". Suggest conservation measures (insulation, picking very efficient appliances, using propane/wood/etc. for heating/cooking, laptop computer instead of a desktop computer, etc.) as these save you money vs just "building" a larger off grid power system.

-Bill

Dave Angelini

Do you really want to be in the cabin in winter? Is it a home or something for hunting or ?
Winter is always the driver offgrid. As the folks above have asked, define everything for better results.

BobAG

Thank you for all the good info. I am new to this forum, so I was not sure what to ask or how much you all would need to know about my needs. What I really want is to pay to have someone design this system for me and I was hoping someone on this forum would direct me to the correct website or person/s that has experience with both hydro and solar. I am pretty sure it gets tricky when a hydro generator and solar panels are juicing the batteries. Like I said earlier I have learned just enough, about off grid, to be dangerous and to know I am in over my head trying to design it myself. Now, having said all of that, I am learning a ton from your responses to my initial post and I thank you for your help. Here are the answers to your latest questions.
1. It will only be a summer cabin May-Oct.
2. 10KW is what I calculated we will use per day. Lights LED , refrigerator with ice maker, fans, TV, electronics, Satellite modem, power tools, washing machine, Misc.  Does 10KW seem to high a number?
3. 310' feet of head is the head after subtracting friction. Our actual head is 500'. Water source is a large spring runs year around probably 100GPM where it exits the mountain side. Yes that is a big number. We ran a 1" line to our cabin and at that cabin have 14GPM of flow out of the  pipe. 
4. I calculated my peak load to be 2000W or about 20 Amps. Probably need to add 20% to be safe.

Here are the areas I do not understand.
1. How and where to ground? Breaker box? Do I bind neutral to ground. Does pure sine vs. modified change any of this.
2. Where do I need breakers between components?
3 Is there one controller that will handle both my hydro and my solar?
4. Do I need to wire the batteries in series or parallel or some combination of both.

I am sure I left some things out, so let me know what else I will need to provide.

Thanks,
Bob

. 

BB.

Even if you hire a designer/installer--Highly recommend going through the basics here (back of the envelope calculations)--Helps you have answers for the person you hire--And you can do some quick calculations on what works best for you and why the trade-offs are made.

The problem with solar is that you are spending a lot of money for hardware (and maintenance)--But only using it 1/2 the year. So, it sort of makes solar "more expensive" $$$/KWH used (the other 6 months of the year, the solar energy is "lost"). And larger solar / off grid power systems are not cheap (batteries being a big cost--And they do wear out/age over time). Also there is the issue of "security"--Will the cabin and its contents be secure the rest of the time you are not there (leave $$$$ in unoccupied cabin--Bait for the bad people out there--And more money lost/cost to replace).

For solar, try to design the system to be "just right" for your needs... And look at your actual needs. Some folks will design a "small" solar power system for "quiet time" (nights, daytime, etc.) when not much loads--And use a genset for days with heavier loads (shop, tools, weekend guests, etc.).

These days, there are some nice inverter-charger systems that integrate with gensets very nicely. "Generator Support" where you use a smaller genset for charging/continuous power needs, and the inverter+battery bank supplies surge / short term loads (tools, induction cook-top, etc.).

If you go hydro--You possibly have 24x7 power available to run your base loads--And need very little in the way of battery backup--Solar, where you have 6-9 hours of sun per day (and bad weather), a relatively large battery bank is critical.

OK--It sounds like 10 kWatt*Hours per day (not kW). kWatts is a "rate" (like 10 GPM). kWatt*Hours is an amount (like 10 GPM * 60 minutes of pumping = 600 Gallons pumped).

For a cabin with a refrigerator... I would be suggesting aiming towards 3.3 kWH per day (3,300 WH)--Yes that is lots of conservation, but worth trying to aim for, even if you don't hit it. 10 kWH per day is a 3x larger system and 3x more expensive (more or less).

Since you are looking at the sunny time of year... You can begin to divide (to a degree) your loads into two types... Those that you run during the day/good weather... And those that run all the time, the overnight base loads (fridge, lighting, entertainment, communications, computer, etc.). Solar panels these days are relatively cheap (and last for several decades)... And the batteries (expensive, 5-10 year life) for carrying the overnight loads--Can be smaller (and base hydro can help a lot here too).

A good place to start.. Get a Kill-a-Watt type energy meter and start measuring/estimating your loads. Fridge, TV, computer, washing machine, etc... And setup a spread sheet:

https://www.amazon.com/s?k=kill+a+watt+power+meter&i=tools&ref=nb_sb_noss_2

Run your loads as you use them (possibly for a few days--Refrigerators use more power in warm/hot weather and even making ice, small laptop vs desktop computer+networking+satellite). It is surprising how much energy (kWH) devices draw that run 12-24 hours per day--Vs the 15 minutes per day of the microwave--And digital devices can huge power hogs.

A 1,200 to 1,800 Watt AC inverter is not bad for a "cabin"... If you want 2,400 Watts or more, then look at a 24 or 48 volt battery bank (thinner wire, easier to bend and connect). Possibly aiming at ~2,400 Watt inverter + battery bank support--And use a genset when needed for backup charging and larger AC loads. You have to decide if you want 120 or 120/240 VAC split phase power.

AC neutral to ground bonding... Grounding is pretty large and complex set of issues... there is grounding for Safety... The neutral+Ground bond allows you to use one breaker/fuse on the "hot lead" and no breaker/fuses on the neutral (since a ground bonded neutral is always at or near zero volts). Saves money and the common ground prevents sinks, electrical boxes from getting energized from a short circuit. That (very quick and dirty) is the reason for Neutral+Ground bonding.

And yes, PSW/TSW (pure/true sine wave) vs MSW (Modified sine/square wave) inverter matters... Most PSW inverters have an isolated AC output (transformer output) and you can bond N+G as needed (per NEC standards). Most (almost all?) MSW inverter you cannot tie N+G together as they are not "floating AC outputs" but tied back to the DC inputs... If you ground bond the battery negative (standard) and tried N+G bond for the AC output--The MSW inverter will usually smoke.

Another question is "earth ground"... An 8-10 foot copper/steel rod driven into the earth at outside edge of the foundation is standard. In some mountainous areas, driving a ground rod is not easy, and may not make good electrical connection--Other methods may be required... And the typical need for "earth bonding" (ground rod) is to direct lightning quickly and safely to the ground--So it does not go through the middle of the cabin and start a fire, kill people, etc...

And if you have chances of lightning--Then surge suppressors are needed on AC and DC wiring (and satellite cables, etc.) to direct lightning energy to earth:

https://www.solar-electric.com/search/?q=surge+midnite

Circuit breakers are needed between "energy sources" and loads... Battery bank bus to wiring, breakers, AC inverter to wiring, breakers. Genset to wherever, breakers, etc.).

I don't know about a combination hydro+solar controller... Solar is pretty much cook book these days (lots of hardware options out there). Hydro is still pretty rare (from what little I have read--Not an expert by any means). And with hydro there is the integration of the mechanical (valving) and electrical (conversion of AC to DC, possibly using MPPT for better efficiency), battery charging control, and feedback/control loop to prevent wasting of water/turbine over-speed).

More or less, if you can "solve" the hydro to battery bank to your satisfaction, "bolting" on solar to the battery bank should not be a huge issue (you can usually tie two or more properly configured charging sources to one battery bank).

The typical lead acid battery is really a bunch of 2 volt "cells" tied together... 3x 2 volt cells in series = 6 volt battery. 6x cells = 12 volts... etc.).

And you parallel the strings of cells together to get the Amp*Hour capacity you need.

Say you want 400 AH @ 48 volts made from "golf cart" batteries (flooded cell lead acid)...

• golf cart FLA battery is 6 volts @ 200 AH
• 8x GC batteries in series = 48 volt battery bank (8x 6 volts in series = 48 volts)
• Take two series strings of 200 AH each, and parallel connect those for 400 AH (48 volt @ 400 AH bank)
• Or you can use 2 volt @ 400 AH cells
• 24 cells in series * 2 volts = 48 volts string
• And since each cell is already 400 AH, then you have a single string of 24 cells giving you 48 volts @ 400 AH

Configuring the battery bank (and solar array, etc.) are really "down the road" calculations. You need to size the system first (is this a motorcycle, compact car, pickup truck, tractor trailer, or what). The hardware choices are based on the basic size (Watts and Watt*Hours) of your system.

Where I would suggest starting is to better document your load needs (120 VAC, 240 VAC?, 12/24/48 VDC for any DC loads?). Are you cost sensitive? Use a genset for backup or even daily support with a smaller battery power system. You have enough hydro (it appears) to build a system without any solar--Why add complexity?... etc.

Will you bury a new penstock fo the hydro? Or will you try to use the existing 1" pipe (for example, what pressure if you draw 6 GPM do you get at the end of the pipe--Will you need a larger diameter feed pipe to have the pressure you need?).

The other suggestion... Don't buy hardware first (on sale, good deal, etc.)... Do the paper design first. There are lots of conditionals for connecting all of this stuff together in a working system.

-Bill