Power My House With Solar Power in Day Time

Yes, there is.

Using batteries would enable night-time use as well.

Sure there is! Was your internet research fruitless? I would even go as far as saying that inverter is the first choice and price wise preferable over the batterie choice, particularly over day but then there is the question - What exactly has to be powered and when and is there mains at all?

More information is needed, but if you search CR4 you get a lot of good information.

The mains is off between 4 to 5 hours during day time at different intervals

I will be powering some lights,refridgerator and small appliances

Why do you have lights on during the day, Bwana?

ok forget light instead consider tv and computer

That's a large load for the sum of the computer and the TV, and both loads can be considered "non-essential", like the lights.

What happened to the refrigerator, please?

What happens when the sky is overcast or it is raining, please?

Why solar at all, when another option would be to battery-charge when the mains is on, and invert for the critical load (whatever it might be) when the mains is off?

What's wrong with a UPS system for things that you need to keep running?

Far cheaper than a solar system.

The stipulation is no batteries. My guess is that an undersized UPS was already tried and failed. A solar system designed to capture enough energy from a 50% cloudy day to power the 2~2.5 kW during most of the day could have a backup battery added to deal with a passing cloud and to store some of the surplus energy. This will probably not be enough storage or collection to work the whole night but will smooth dips out.

A UPS may be cheaper and more reliable even if it was not what the original poster had requested.

I agree. One or many strategically placed and sized UPS will likely be a much more cost effective solution to rolling brown/black outs than a battery-less solar system. Particularly when a small cloud or plane blocks the sun causing electronics to frequently reboot.

You say your mains are off 4 to 5 hours a day, different intervals, does this mean your mains are on all night long? And you need to make up the difference for just when the mains are doing the brown out issue to protect your food and have some entertainment during these times?

I believe that you're worrying about the trivial part of the design, the inverter. This is like deciding on the type of bridge design before knowing the distance to be spanned or the traffic type on the bridge.

I would start with identifying the magnitude (a number, not a vague description of devices being used) of your anticipated electric power usage. I would next identify how large of a solar array you'd need to provide this power with the sun at a low angle or an overcast day. Then and only then would I wonder about an inverter.

The peak load is close to 2kw maximum

And the average load? What is that?

That's not going to work. I asked for multiple pieces of information to get only one new piece of information. That iota wasn't even what I asked for, too.

I wonder what this guy is going to do for power if the power fails on a rainy day or at night?

1939s1

You need to think of a off grid inverter. A grid tie inverter will not work when the power is off. Check for RV, camping or boat types. And make sure you are off the grid when connecting the inverter to the load(s)

buy anything over 2.5kW (e.g. road master)

Bottomline is that the output of PV panels is not constant and varies depending on the Sun/ToD/weather etc.

So, you can avoid battery backup provided you / your loads are OK with the above fluctuation and sacrifice the quality of available power.

You only know your requirements the best and hence you are the best judge.

There are inverters for every purpose....but collecting sunlight for energy is much like collecting rainwater for drinking, a big barrel with a small faucet is the way to go....the batteries act as a storage medium and smooth out the fickle supply of sunlight....without this buffer zone you will experience an uneven electric supply that will damage your electrical devices which are not designed for wildly fluctuating voltage.....

http://www.affordable-solar.com/store/solar-inverters-off-grid/Outback-GS8048-Radian-8Kw-120-240VAC-Inverter

Dear SolarEagle,

The analogy "collecting sunlight for energy is much like collecting rainwater for drinking, a big barrel with a small faucet is the way to go" is very appropriate.

In reality there are dozens of options available to you. To start off correctly you need to have a budget. How much money can you afford to invest in solar panels and other equipment? If you are limited to a tiny budget then your options are also limited.

For example, I built a solar water pumping system which only works during the daytime and has no batteries. Using the number of solar panels recommended by the pump supplier did not work very well because the pumping would drop off during cloudy periods which were frequent so the owner asked me to triple the number of recommended panels. Now his system works great and pumps early in the morning and during cloudy days.

The bottoem line here was money. He could afford to buy more panels to get the results he needed. Also, during sunny periods he can use the excess power to do other things.

On another note one contributer said grid tie inverters do not work when grid power is present. This requirement was established to avoid back feeding a failed grid and possibly electrocuting power line workers however many of the newer inverters like the OutBack Radian series have overcome this issue and use a disconnect system so you can still use your solar power even when the grid has failed.

Again, it depends on your budget. At my house I have a 1Kw solar array mounted on trackers, a large AGM type sealed battery bank, an OutBack MPPT solar charge controller, an EXELTECH 5kW pure sinewave inverter and 3 IOTA chargers which only connect to the grid if the battery voltage gets too low. We run the house during the day on solar power as you want to do. In this country we can have unpredictable power failures both at daytime or nightime so the batteries are a necessity. We have about USD20,000 invested. Can you afford this?

Best Regards

John

Thank you John for your input

I understand the problem if the solar panels are not enough especialy during cloudy days,but this cn be solved by adding more panels and the money is not a problem as long as the system works

I am trying to find a good off grid inverter that can do the job. If you know of one please tell me about it

.Does your inverter for the water pumping have an mppt contoller

By the way where i am the average yearly sun hours is over 5

Best Regards

1939s

The average yearly sun hours is over 5 everywhere on this planet, Boss.

Look into what Midnight Solar has to offer.

Based on your "no batteries" criteria you might want to check out ENPHASE. This company sells solar panels with mini inverters in each panel which convert the DC from the panel into AC for use in your house. They are very simple and easy to install since you dont have to deal with any DC wiring, batteries, MPPT controlers etc etc. And they are supposed to be very efficient. You just cable out the AC side of the mini inverters in light gage wiring to junction panels and feed the house. If you need to grow you just add more panels with the mini inverters. They also have a control panel which tells you how each mini inverter is doing and makes it easy to find any problems.

I have not worked with this equipment but I am considering it for a client who, like you, doesn not want to deal with batteries. He has a generator for night time black outs.

Ciaoo

John

Thanks John i will check it out

The enphase, just like all the other grid tie systems need a reference "grid" voltage to work. They "copy" the source, before adding feedback. The minimal working condition for off grid, is to have a stable DC supply (like a battery) to make the electronics perform.

I did not realize that the ENPHASE needs a line reference. Thanks for the info. Could he build a mini-grid using a small inverter and just a couple of batteries. If this is possible he can "fool" the ENPHASE into thinking the grid is present and operate that way???

Hi John

I checked with Enphase and they said their system requires a gid

The engineer told that they have an off grid AC coupled system wher the system is tied to a generator panel .Here the generator is the line reference.

If we use a big solar system and a small generator will that work

I asked him this question ,but never got an answer

I have done that before. The problem is that the reference wave source needs also be able to "receive" the power output of the inverter. To give an example just as info:

If your reference can generate 100 watts and provide the required sinus, within specs (frequency stability, voltage range, etc...) your enphase will kick in and deliver let's say 250 watts from a bigger size panel to the source, this can be too much and destroy your reference source - a small generator will burn out and also an inverter.

Here you make actually an artificial grid-tie system. The conditions however are that the source is a lot more powerful than the solar feedback. D

Thanks John i will check it out

There are solar inverters in the market to run water pumps by solar panels and no battery

Do you thing they can run house loads

Yes, they are called Linear Current Boosters. I just installed one on a SHURflo 9300 series submergable well pump and its a Dankopp DL16A. What it does is make a better match between the solar panel energy and the pumps DC requirements so the pump starts earlier in the morning and extracts the maximum power from the solar panels. They use the same MPPT technology but give DC output. Maybe if you modified your house loads for DC use it might be an option but we are assuming you want normal AC power, 120V at 60Hz, correct?

I sent out your question to OutBack and also to a very clever friend in Canada who builds solar systems all over the world. No answers yet.

You may be forced to go with batteries even if you dont want to. Your request has certainly stimulated a lot of thoughts.

Thanks John and please let me know the response of your friends

Sorry to respectfully disagree.

Some things do not match in your narrative. You need to understand how MPPT works and to claim that the pump starts earlier with that DL16A is wrong. MPPT only starts working when the conditions: voltage and current are present. The open circuit voltage of a 12 Volts panels is between 20 and 21 Volts (when you have a good one). A typical MPPT working value is 17 volts. Since when can the regulator make it work, before this point is achieved?

Your pump will also run at different speeds, according the sun energy gathered.

P= U.I (P= power, U is voltage, I is current) and when this combination does not match your load, unbalances will occur. The pump must be designed for the maximum your system can provide, or you must dump the overproduction in a extra load.

Powering your house in a reliable way without buffer batteries is a big NO.

Hi John

I like to send you specification of the off grid inverter i found to take a look

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Thaks ,but i am looking for an off grid system with no battery

I hope you are not in a hurry. You can start making a design for probably the first one. A solar panel is different from a battery. Read output diagrams vs. light exposure. Your main problem might be energy levels between shortage and over-load. MPPT is not going to be able to compensate for it, following differences re: low outputs and excessive dangerous production levels for your loads. (breakdowns to destruction of components). Good luck.

You said "Thaks ,but i am looking for an off grid system with no battery"

Well... Pumped storage and micro-hydro, geothermal, wind.... What are you doing about water supply?

Solar power is good to light your home, but only in the sunny season, but what if there is no sun in the sky or on cloudy or rainy seasons. I think using another option will be better instead of solar power.