250W Photovoltaic Panel: Battery Capacity for 1kWh/24h Usage, MPPT Load & Gel Battery Options

Question

Hello. I would like to take 1Kwh / 24h from the battery at a 250W panel. Therefore, I wanted to ask those who know whether it is possible and what battery capacity to use. I have an mppt load driver. I'm looking for a gel battery now. greetings

Xantix · Accepted Answer

1 kWh is stored in a 12 V battery with a capacity of about 85 Ah. Of course, this is the theoretical minimum. In practice, an amendment should be made to the finite efficiency of the battery, and also to the fact that the batteries should be discharged to zero because this significantly shortens their life. Therefore, I suggest taking a battery at least 50% larger. It is possible - but not at all times and under all conditions.

vodiczka · Accepted Answer

From the battery side: 1kWh is otherwise 12V x 83.33Ah
Panel side: 250W x 8h = 2 kWh
Taking into account the efficiency of charging the battery, on a sunny day you will charge it calmly, but when it is cloudy, it will be a problem because depending on the degree of cloudiness, the panel will give away from 30 to 100W of power, which is too little to cover the daily energy demand.

3301 · Accepted Answer

On a sunny day, such a panel will charge the battery even 100Ah discharged to the acceptable level already before noon and if there is no additional load, the rest of the energy will be wasted. In order to optimally use the capacity and energy stored in the battery, it should be discharged with a current of 20h, which at 100Ah is 5A at a temperature of 20 degrees. batteries

vodiczka · Accepted Answer

Please calculate. The author of the topic does not mention that his panel will follow the sun and that he will only use it between June 10th and July 5th when the days are the longest. I have the impression that my colleague, early afternoon was mistaken for morning. In my opinion, no more than 160 Ah. If the batteries are deeply discharged, which may happen over a few consecutive cloudy days, batteries with a greater capacity may never fully recharge.

3301 · Accepted Answer

In my opinion, there is nothing wrong here, and my friend gave the calculations: Following the conversion, it would be 8kWh from 1kWp per day, which is real, although I obtained 6.8kWh max with 1kWp and also using my experience because I also use 16 batteries at 100Ah and 4.32 kWp on the roof which gives 270W / 1 battery 100Ah, so even a little less power on Ah than the author of the topic would have, after 12:00 on a sunny day, if I do not load more UPS than usual, some energy returns to the clouds. So if there are more of these Ah in stock, they will be less intensively discharged with the assumed consumption of 1kWh, which gives only advantages.

Wr841nd · Answer

What is the MPPT driver?

RAINBOWBRIDGE · Answer

I have BlueSolar by Victron MPPT 100/15

vodiczka · Answer

From my no calculations compared to the assumptions (panel and battery), there was a large excess of power on sunny days and at the same time its shortage on cloudy days. The author of the topic did not specify whether the installation should operate all year round or only in summer or only on sunny days? He also did not say whether the demand for energy is from dusk to dawn or, for example, is 40% from morning to evening and 60% from evening to morning. Only when you have all the data you can perform calculations and select the panel power and battery capacity. The author of the topic has a 250W panel, i.e. he would have less power for a 100A battery and a friend suggested 2-3.

RAINBOWBRIDGE · Answer

The installation is to be year-round, energy demand will be dimmed. I would like the battery to be charged in the morning and in the afternoon.

Xantix · Answer

As the whole year is supposed to work continuously, in order to ensure this 1 kWh in all conditions, the panel would have to be at least a dozen times larger than at present (I would aim at about 2 kW). IMHO, forget to ensure that this installation is operational all year round in reasonable money. In winter, it will be cheaper to charge the battery with electricity from the energy sector.

vodiczka · Answer

In my opinion, 1kW should be enough, as long as the sequence of consecutive days with strong cloud cover is not too long. When it is overcast, the panel optimally set for winter conditions (in summer it will provide excess power without moving it) should produce a minimum of 0.8 kWh / day. The remaining 0.2 kWh can be obtained at the cost of gradual discharge of the batteries.

RAINBOWBRIDGE · Answer

Thank you for the information. So with one 250W panel I will not do anything? I'm starting to regret buying it.

vodiczka · Answer

Unfortunately not. What was this set supposed to power? Where to work Is it possible to recharge the battery from the mains or not?

RAINBOWBRIDGE · Answer

Initially, a laptop and LED lighting, there is a possibility of recharging, but I do not see any sense in recharging the battery from the network, you can also connect everything to the network and give it a rest with the panels

Xantix · Answer

You know, it can be even more cost-effective to use electricity from the energy sector - especially in winter ...

vodiczka · Answer

Since you have already bought, you can use the set in the summer and personally observe the difference in work depending on the degree of cloudiness. Treat the installation as experimental. You will also find out (after a long time) that if you do not use some of the energy on a regular basis, it is not as good and it is better to use electricity from the network, unless you have access to partially used batteries for the proverbial one zloty.

Kwazor · Answer

You can do it easily. My configuration is up to 180W + 150Ah battery and I do not know what external charging is. Laps runs an average of 6 hours a day a day and does not feel even on 1 panel, i.e. 90W, would not charge my battery when I am not there. Only in winter there were some deeper discharges (about 30%) because the weather was not daily. The laptop uses an average of 31W and takes about 2.5-3.5Ah from the batteries per hour.

vodiczka · Answer

With a laptop, yes, especially when it works no longer than 8 hours a day, but we know nothing (power, working time) about LED lighting.

theo33 · Answer

Hello and welcome
I have been observing topics related to photovoltaics for a long time, I also test the 180W 24V panel and the 108Ah battery connected via the inverter and I need advice what is wrong because after two days of charging the battery voltage is 13.2V at 3A current and nothing rises despite the fact that on the inverter input is 25V.
The converter has an input range of 15-30V and an output of 13.8

3301 · Answer

As I wrote in another post, check the inverter and this panel.

romanha1 · Answer

And is it not possible to use an inverter with a VOlta sinus pro 1000s controller?

If it is true what the manufacturer says, if there is no electricity, it will switch to the mains current and charge the battery, unless the straightener does not work as specified by the manufacturer.

Can anyone comment on this voltage regulator with an inverter

250W Photovoltaic Panel: Battery Capacity for 1kWh/24h Usage, MPPT Load & Gel Battery Options

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