can i use a solar panel without using battery

[Bucho]

Are you trying to describe a "grid tie system" where a very special type of inverter takes power from a string of PV panels, and feeds that into the grid? In that case, the grid acts as the battery.

Somewhere, you need a battery, either the "grid" or a bank of batteries.

Panel and load only works for some special water pumps with expensive control modules.

What about the Sunny Boy's SPS feature?

https://www.youtube.com/watch?v=fF461YYNbtw

[solarix]

This falls in the philosophical category of - there is no free lunch. Electricity is useful stuff, it should make you useful enough (lights at night for example) that you can afford it. Yes, this means batteries - yes, they cost a bunch and require some effort to maintain. But, don't be cheap and try to do the impossible of off-grid w/o batteries. Don't be cheap and live in the stone age because you can't afford batteries. Don't be cheap and buy into some company's financing that will keep you in debt. Don't be cheap and cry for cheap rates from your utility forcing them to make their power from the cheapest, dirtiest, energy sources. Don't wish for winning the lottery - cause you'll blow that on useless stuff. Don't just pray for a miracle, cause God expects you to do your part too.
Thanks for getting on this forum - we're giving out for free the educational keys to the solar kingdom here.

[almac]

What about the Sunny Boy's SPS feature?

https://www.youtube.com/watch?v=fF461YYNbtw

so you can run directly off solar panels, all the experts on here saying that you cant are WRONG

[almac]

You still have not answered the basic question; How much power are you using? Most of the responses of why it doesn't work are for economic reasons for large multi Kwatt systems. It is certainly not impossible to pull power from a solar system and it is not impossible to run appliances from a solar panel, you just have to deal with the variability of the supply (i.e. the sun) and the variability of the load (e.g. startup loads).

If you want something to supply power all the time (e.g. when the sun is gone), you are talking batteries as the most economical. If you can go without power at night then you don't need as much battery capacity. Now you are down to the next largest variability which would be sun obstructions lowering panel output. If you can live with anything less than say 1 hour just cut your battery capacity 16 hours (overnight loads) down to 1 hour (day time loads). You actual usage will dictate if that could give you a 10:1 factor or not in battery capacity.

So the bottom line is you have to either

a.) accept(loss of power) or
b.) deal with the variability (draw on reserve storage of power previously harvested).

The variability comes in two primary forms:

1.) the solar power generation and
2.) the loads placed on that generation.

Most of the answers by experts are in class b.) for kwatt based systems which economically is cheapest using batteries whether the variability is 1.) or 2.)


A strategy to take option a.) by reducing loads under 2.) does reduce battery capacity requirements as you should now well know.

i dont know how much power i use. its not too much, not so much i overload my inverter. and not so much i drain my batteries. have more than enough power from a 1.5kw solar array. thats it!

[SunEagle]

so you can run directly off solar panels, all the experts on here saying that you cant are WRONG

There are specific applications that allow you to run your loads directly from solar panels (like DC motor water pumps and fans). The problem with just using panels can result in an inconsistent power supply which some electrical loads do not like.

I have a couple of roof vents that work directly from a 10 watt panel. They were designed that way but will vary is speed based on the amount of sunlight hitting the panel.

To insure a consistent supply of power for your loads it is better to use the grid, a battery system or generator set. That is the only way most AC loads will run properly and not burn out due to low voltage or too many "starts".

[Bucho]

so you can run directly off solar panels, all the experts on here saying that you cant are WRONG

When equipped with an SPS module the inverter is capable of switching from interactive operation to stand-alone operation. In stand-alone operation the inverter can supply standby power to a dedicated power outlet that has been wired to the SPS module within the inverter. When sufficient sunlight is available this outlet can be used to run small appliances and charge electronic devices during prolonged utility power outages.

I've seen one of these systems in use in Rehoboth MA. it is an actual thing.

It's by no means a replacement for a battery bank which is I think what the OP's after but for those with big grid tied systems who want to get a little power during outages, that has become a doable thing.

Here's a recent thread on it: http://www.solarpaneltalk.com/showth...light=sunnyboy

[posplayr]

I've seen one of these systems in use in Rehoboth MA. it is an actual thing.

It's by no means a replacement for a battery bank which is I think what the OP's after but for those with big grid tied systems who want to get a little power during outages, that has become a doable thing.

Here's a recent thread on it: http://www.solarpaneltalk.com/showth...light=sunnyboy

Basically the SPS is sized to some fraction of the solar charging rate capacity so that the little bit siphoned off is not enough to pull the line voltage down.

[inetdog]

Basically the SPS is sized to some fraction of the solar charging rate capacity so that the little bit siphoned off is not enough to pull the line voltage down.

Total nonsense.
The SPS is a separate inverter control algorithm from that used for GTI operation and may not even have many parts in common other than the MPPT input circuitry.
It cannot be used at the same time as the GTI function by design.
A GTI designed for maximum output and efficiency at minimum cost will not have the components or design features to also deliver stand alone power at a lower maximum value from the same panel input.
The reason that you do not see standalone inverters with PV input and off grid output and no batteries is that it does not currently make economic sense. There is not a market for it. Laws of Economics rather than Laws of Physics.

[posplayr]

Total nonsense.
The SPS is a separate inverter control algorithm from that used for GTI operation and may not even have many parts in common other than the MPPT input circuitry.
It cannot be used at the same time as the GTI function by design.
A GTI designed for maximum output and efficiency at minimum cost will not have the components or design features to also deliver stand alone power at a lower maximum value from the same panel input.
The reason that you do not see standalone inverters with PV input and off grid output and no batteries is that it does not currently make economic sense. There is not a market for it. Laws of Economics rather than Laws of Physics.

Rather than call my statement total nonsense, you might have bothered to think about what I meant.

With a careful reading I don't think I suggested that the GTI and SPS had anything in common other than perhaps some of the power circuitry (the inputs after all are the same). In fact I'm pretty sure I have posted that they are two clearly different modes of operation, GTI is a programmable current source to optimize power delivered to the grid despite variability in those voltages and SPS is output voltage regulated. And I think any reading on the subject of SPS, it is clear that SPS and GTI are operationally mutually exclusive and have to be.

Despite, the variability of solar production and load demand SPS operates without batteries. Why do I need batteries to power my house using solar panels during solar daylight hours? One primary reason, surge requirements which is what necessitates an energy storage medium. So how does SPS operate without batteries, the excess panel power has sufficient capacity to deal with the surge requirement at 1500 watts.

I would go so far as to suggest that if it was so simple to just switch the invertor mode from GTI to Voltage Mode at full load capacity without batteries it would have been done by now, the market demand is there, it is just not possible.

[inetdog]

Rather than call my statement total nonsense, you might have bothered to think about what I meant.

With a careful reading I don't think I suggested that the GTI and SPS had anything in common other than perhaps some of the power circuitry (the inputs after all are the same). In fact I'm pretty sure I have posted that they are two clearly different modes of operation, GTI is a programmable current source to optimize power delivered to the grid despite variability in those voltages and SPS is output voltage regulated. And I think any reading on the subject of SPS, it is clear that SPS and GTI are operationally mutually exclusive and have to be.

Despite, the variability of solar production and load demand SPS operates without batteries. Why do I need batteries to power my house using solar panels during solar daylight hours? One primary reason, surge requirements which is what necessitates an energy storage medium. So how does SPS operate without batteries, the excess panel power has sufficient capacity to deal with the surge requirement at 1500 watts.

I would go so far as to suggest that if it was so simple to just switch the invertor mode from GTI to Voltage Mode at full load capacity without batteries it would have been done by now, the market demand is there, it is just not possible.

To me "so that the little bit siphoned off is not enough to pull the line voltage down." implies that the SPS will be running while there is line voltage present, unless you were referring to the DC bus. In which case the MPPT input makes the panel side voltage irrelevant.
It is true that the SPS may depend to some degree on a fractional cycle energy storage capacity inherent in the MPPT front end, but that has to be there for normal GTI operation only more so.

[posplayr]

To me "so that the little bit siphoned off is not enough to pull the line voltage down." implies that the SPS will be running while there is line voltage present, unless you were referring to the DC bus. In which case the MPPT input makes the panel side voltage irrelevant.
It is true that the SPS may depend to some degree on a fractional cycle energy storage capacity inherent in the MPPT front end, but that has to be there for normal GTI operation only more so.

Sorry if I was not clear, the response was to the context of the OP question where he is trying to understand how SPS works without batteries when he has been told on the other hand how you can't use solar without batteries. (please read the title of the thread)

"little bit siphoned off", is referring to a portion of the total power available at the panel.

In SPS mode "line voltage" can only mean the output of the SPS as the grid is not there or disconnected (i.e. mutually exclusive with GTI which does operate as full output power). And I think most anybody with any background in this will realize that even the SPS 1500 watt will not likely be able to run a 500 watt motor with the surge requirements (motor surge being typically higher than even 3:1) without severely dropping the "line voltage". Perhaps terminal voltage would have been better choice.

My whole point was to explain in the simplest (non technical) terms why SPS did not needing a battery but was not in contradiction with in the general consensus that a solar panel can't be operated at full power without a battery storage capability. Even that is too absolute a statement, to my mind the issue is (as I also posted), the battery system is there to deal with the aggregate variability of loads and solar production.

If you just want solar during the day, you only need a battery scaled to the load (i.e. surge) requirements. If you want to go all night, then the battery is scaled to the solar variability which is obviously not there.

In this context, the only thing you can say about SPS is that the surge demand above and beyond the 1500 watt capability has to be either in excess solar capacity (unused solar watts) or capacitors in the case which there seem to be plenty in the Sunny Boy TL products. Where else could it come from? I guess there was an transformer version.

[inetdog]

Terminal voltage would have been a much clearer choice.
In any case, as I understand the SPS, it does not have any surge capability at all. If it is asked to deliver more current than it can at the moment (not necessarily even the rated 1500W if there are weather or shading problems) it just shuts down rather than dropping voltage and trying to hang in until it overheats the way a battery inverter usually will.

[posplayr]

Terminal voltage would have been a much clearer choice.
In any case, as I understand the SPS, it does not have any surge capability at all. If it is asked to deliver more current than it can at the moment (not necessarily even the rated 1500W if there are weather or shading problems) it just shuts down rather than dropping voltage and trying to hang in until it overheats the way a battery inverter usually will.

Another absolute statement ;

it must have some capability else you could not even stick a laptop charger into it. But in effect I'm agreeing with you that whatever limited surge capability SPS has, it is limited. Whether you agree that the SPS is limited because it doesn't have a battery, it is clear with a battery and dual conversion SPS would have much better surge capability as in the case with a UPS sized for the 1500 watt SPS.

I think this is as close as you can get to answering the OP's original question.

[Beanyboy57]

What is your total, annual electrical energy consumption ?

You may not believe it but we are now down to an average of 5 kWh per day so that works out to roughly 175 kWh per year. Admittedly I am away from home for a large part of the year and we use natural gas for cooking and heating water but there is always someone living in the house.
I have a 3kw grid tied system on the roof of the main house and a 1kw off-grid system on the roof of my shed that has been operating for the last 3 years. Sunny Boy inverters produce around 19 kWh per day on average.
The grid tied system has already paid for itself after 4 years and I regularly receive a payment from my electricity provider of around $1000 per annum. I have not paid any money to the electricity supplier since the install in 2011.
The 24v off-grid system costs me around $4000 (because I bought high quality components and I live in Western Australia where everything is expensive) to set up and will never pay for itself although it may break even in two years. It has been a lot of fun though as I learned a lot about FLA batteries, charge controllers, inverter/chargers and power monitoring. I have several hobbies and the off-grid system in the cheapest of them all. Hahaha
Thanks to the advice of the experts on this site my FLA batteries are in excellent condition after 3 years of continuous cycling to around 30% DOD (70 % full).

[J.P.M.]

Having lived comfortably on about 2,200 kWh/yr. for about 7 years or so in the first hose I owned, I believe you. You're also not in America where usage, for better or worse, seems to be profligate.

Nicely done.