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bgreely asked

smartsolar mppt 75/10 use with hydro

Hello, I have a hybrid system using solar and hydro. The solar is connected to a mppt smart solar 100/50 and the hydro is connected to the mppt 75/10. My battery bank is 4-6volt in series giving me a 24V system. Recently my hydro portion of this system stopped working as expected. I normally see my input voltage around 30-35 current around 3.5amps. A few weeks ago voltage shot up to over 70 and my current dropped to 0.2. I stopped the hydro and reset everything. Since then Most of my power is going to my load instead of my batteries, even when my battery voltage is below 23V. Basically I never get any power to my batteries it is always going to load. So recently I changed the load setting from BatterySaver to Custom algorithm 1 and set ( Load OFF Vbatt < 24.1 Load ON Vbatt >27.8) This seemed to work for a few days, but this morning my batteries voltage was 23.1 and all my power was going to load. So, I did some more reading and removed the jumper from the 2,3 pins. All was going well until about an hour ago when I my mppt was showing voltage over 70. I have now shutdown the hydro and do not know what to do. Any help or suggestions will be greatly appreciated. Oh here are a few things you should also know.

1. I am very very new to this off grid system, I did not design it or install it, both were done professionally.

2. I have read enough to know Victron smartsolar controllers do not support hydro. I am not sure why the system designer used the Victron 75/10, but he did so I am trying to make it work.

3. Out of necessity I have learned enough to keep the system running, but that is it. I do not know all the acronyms, controller and EE terms I read in the QA, so be patient with me.

4. I can upload a diagram of the system if that helps.

MPPT SmartSolarHydro and Wind Power
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mvas avatar image mvas commented ·
Can your hydro go above 75 volts?
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bgreely avatar image bgreely commented ·

I may have come up with a solution to my problem. On the 75/10 controller I did the following:


Changed Battery settings to, absorption 26.9, float 27.18

Changed Load output settings to. User algorithm 1 (OFF <24.04 Vbatt, ON > 27 Vbatt)

After 2 days with these settings no more voltage faults.

I stil have a few questions.

1. The controller never goes into absorption or float, it flips to load as soon as the batteries hit 27V. This tells me the battery settings are being overridden by my Load settings? They do not work together, it is either battery settings or Load settings?

2. Is this configuration hard on the batteries?

3, When I pulled the jumper I broke it. Where do I get a new jumper? in case I need it in the future.

Thanks,

Bob


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Mike Dorsett answered ·

The main problem with using Hydro (or wind) as an input to the MPPT controllers is that once the battery is charged, there is nowhere to put the power from the source, so the load on the source is reduced, and the Hydro or wind generator will over-speed and produce a high voltage, or cause damage to the generator by excess rpm (possible). The system does not have a dump load for the excess.

However, if the generator can tolerate the over-speed, then the MPPT can be used - provided the voltage is in range. An MPPT will try to short it's input if the voltage gets too high, whit a motor source, this normally results in destruction of the MPPT's protection.

you don't describe what your load is...

If you are using 6V traction batteries, then these can tolerate quite a bit of overcharge, provided you keep the acid levels topped up. your absorption voltage should be higher than your float voltage - normally it is impossible to set this lower - 28.8 for absorption, and you could make the float voltage anywhere from 27.6 to 28.5. Setting the load switch on above 24.5 and off below 24 would also work. The fact that you never see float just means that the load is high enough to keep the MPPT controller in bulk mode - use Victron connect to see what your voltages are doing over the course of a day.

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bgreely avatar image bgreely commented ·
Thanks Mike for your answer, explaining the over voltage, and not using big fancy words :). I do have a dump load (200 W, 24 V) and my batteries are interstate lead acid 6V golf cart.


With my latest settings (see comment above) it seems to be switching between dump load and batteries. I am curious about your float and absorption settings. I thought absorption should be lower than float, since absorption is the second state and float is the 3rd.

Any ideas on my 3 questions I asked in my previous comment?

Thanks,

Bob


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