How to control excess pv power production

[Kun]

Hi,
I want to design a solar system but with the following parameters

1. I don't want my system to send power to the grid . But take power from the grid when pv is not producing the house requirements.
2. How to control the excess power production
3. Don't want Battery backup as I have already have 3 ups @ 2 KV - 24 Volt - 300 amp lead acid battery installed running the critical loads .

Help on this would be appreciated.

Thanks

Kunal

 

[DThames]

Look at this.

 

[efficientPV]

You left out #4.......What loads do you have that can randomly diverted to. Pumping, hot water, space heating, ventilation/AC are possibles. I divert to heat water. it is eye opening when you attach something that records the diversion. If not grid, your options are limited.

 

[Kun]

You left out #4.......What loads do you have that can randomly diverted to. Pumping, hot water, space heating, ventilation/AC are possibles. I divert to heat water. it is eye opening when you attach something that records the diversion. If not grid, your options are limited.

What are options if not the grid ?

Guys I am setting up this system at my parents house in India and unfortunately the grid tie system are only allowed in the city's not in the country .

Hence the problem what to do if the array is producing more electricity than their requirements.

 

[efficientPV]

With the suns energy free, solar people tend to be big energy wasters. There just aren't that many opportunity loads. Those that could be used require an energy management system that holds off powering them until absolutely necessary or when extra energy exists. Systems like this are complex and don't lend themselves for the average consumer to set up. With a house already functioning, you have to invent some frivolous loads.

 

[DThames]

What are options if not the grid ?

Guys I am setting up this system at my parents house in India and unfortunately the grid tie system are only allowed in the city's not in the country .

Hence the problem what to do if the array is producing more electricity than their requirements.

Without a storage (battery) there is no "excess power production". There is potential power production but the power produced is what the load consumes plus conversion losses. It is not like trying to stop a flood, but trying to pull from the panels what you are currently using....if that makes sense.

 

[wattmatters]

Hence the problem what to do if the array is producing more electricity than their requirements.

They won't ever produce more than required. The solar inverter won't allow them to.

A solar inverter only draws from the panels the required power, up to the limit the panels are able to supply.

e.g. Say an array of panels in the middle of a sunny day are capable of producing 2000W while the loads only require 500W. The inverter's MPPT controller throttles the production from the panels such that the panels only supply 500W. If you then add an extra load and began to use 1000W, the inverter's MPPT controller will adjust its settings to draw more power from the panels. Modern inverters can adjust the power drawn anywhere between zero and the maximal output the array is capable of supplying.

 

[Kun]

L

Hi,
I want to design a solar system but with the following parameters

1. I don't want my system to send power to the grid . But take power from the grid when pv is not producing the house requirements.
2. How to control the excess power production
3. Don't want Battery backup as I have already have 3 ups @ 2 KV - 24 Volt - 300 amp lead acid battery installed running the critical loads .

Help on this would be appreciated.

Thanks

Kunal

They won't ever produce more than required. The solar inverter won't allow them to.

A solar inverter only draws from the panels the required power, up to the limit the panels are able to supply.

e.g. Say an array of panels in the middle of a sunny day are capable of producing 2000W while the loads only require 500W. The inverter's MPPT controller throttles the production from the panels such that the panels only supply 500W. If you then add an extra load and began to use 1000W, the inverter's MPPT controller will adjust its settings to draw more power from the panels. Modern inverters can adjust the power drawn anywhere between zero and the maximal output the array is capable of supplying.

Thanks a lot , This is great , so now would you be kind infough to explain me that is this feature is available in all solar inverters or is there are any specific features / control on them to look for

 

[wattmatters]

Thanks a lot , This is great , so now would you be kind infough to explain me that is this feature is available in all solar inverters or is there are any specific features / control on them to look for

Any standard solar inverter or charge controller should do this automatically.

Solar inverters and charge controllers will typically use either an MPPT (maximal power point tracker - some have more than one to connect multiple PV arrays), while cheaper charge controllers may use PWM (pulse width modulation).

Which type is suitable for your needs depends on what you are using the panels for, how large the system is and your budget.

PWM are typically good for lower cost smaller systems and lower voltage panels where trickle charging batteries is the main application. MPPT is usually a better choice for larger systems with higher voltage panels where, apart from charging batteries, it is supplying power for appliance loads and you want to extract as much energy out of your PV array as possible.

You can Google the differences between MPPT and PWM to learn more.

 

[GSXR1000]

simple answer, not used a ups but as buffer for the 14 without sun..

 

[GSXR1000]

that's cost $142 per KW

 

[GSXR1000]

you can get a all in one that switches to grid once your batteries get low

 

[DThames]

L



Thanks a lot , This is great , so now would you be kind infough to explain me that is this feature is available in all solar inverters or is there are any specific features / control on them to look for

Regarding the previous statement "Hence the problem what to do if the array is producing more electricity than their requirements", which you still seem to be asking about.....IT is not a setting nor is it a control. It is the nature of electricity, power supply and power consumption. If you are connected to the grid, the grid produces way more power than you need or will use. But it doesn't matter. You use what you need from what is available.

In an off grid solar installation, the same thing is true. Ideally you can produce more than you need so you never fall short. Being "able" to produce more than you need is not a concern. Maybe a cost concern but not technical concern.

 

[GSXR1000]

another take.. use a all in one with a smaller battery... then set your UPS to lose power from 8pm till battery voltage gets to 12v (or 6am)
then your solar can recharge your UPS

 

[efficientPV]

It is a simple idea, but fairly hard to implement. There are may crude ways to divert excess energy. These only collect some of the energy which is better than nothing. You need an opportunity load that can come on for even a short period of time that still isn't absolutely necessary. Holding off on demand loads like water pumping and heating/cooling is a good way. Statistically excess energy will come available daily to meet these needs.

 

[Kun]

So here is what I have understood so far . Sorry If I am wrong as I am new to this .

A. I can install a solar inverters to power the house , the power production will be as per the load required .

B. When the power production of the PV drops as the day goes by the grid power will kick in as per the load required .

C. I don't need to install battery backup for the solar inverter for it to power the load .

D. The grid power and the PV panels will get connected to the solar inverter and then the output from the inverter will go to the distribution box and the inverter will stop pv power flowing in to the grid .

 

[GSXR1000]

So here is what I have understood so far . Sorry If I am wrong as I am new to this .

A. I can install a solar inverters to power the house , the power production will be as per the load required .

B. When the power production of the PV drops as the day goes by the grid power will kick in as per the load required .

C. I don't need to install battery backup for the solar inverter for it to power the load .

D. The grid power and the PV panels will get connected to the solar inverter and then the output from the inverter will go to the distribution box and the inverter will stop pv power flowing in to the grid .

I will say due to fluctuate of clouds and such you need a small battery ... let's say 2kw so you can set an constant load without it failing over to grid all day long

 

[HighTechLab]

Sol-ark handles all of this with the "limited to home" options, but with a hefty price tag. When PV exceeds the home's load, it just tapers back production if no batteries are present.

To emphasize, batteries with Sol-ark inverters are totally optional.

It can also handle if you eventually want the mentioned diversion loads or want it to act as a UPS with batteries in the future.

 

[GSXR1000]

Sol-ark handles all of this with the "limited to home" options, but with a hefty price tag. When PV exceeds the home's load, it just tapers back production if no batteries are present.

To emphasize, batteries with Sol-ark inverters are totally optional.

It can also handle if you eventually want the mentioned diversion loads or want it to act as a UPS with batteries in the future.

but since he isn't grid tie the system.... how will it scale back production with all the loads attached? it can't provide less power with our loaf shedding loads and that gets complicated

 

[Kun]

I have received another suggestion please advise

Get a hybrid solar inverters with zero export device .

Add backup as and when whish to and as much possible