These videos will take me far in my studies of Photovoltaics. I came across them at the right time. Thank you..

Thank you. Your tutorials are so easy to understand. One day I will have finished my solar power plant to become independent from Russian oil and gas.

@Yagyaansh

2 жыл бұрын

i didn't expect to find this comment here. lol.

Thank you for posting these facts. A neighbor with solar panels was without power for 6 hours today, after a storm, because he is tied to the grid. That's why I', searching off-grid.

@AltEStore

7 жыл бұрын

Exactly. We did a few videos on options for adding batteries to a grid tie system after the fact if your neighbor is interested. kzread.info/head/PLoHd6hGDqS05HGtV7P-vsRJsDw11R4Bb4

Very much informative. thanks.

Thank you

what do you mean by the system efficiency? How can I calculate it? thanks.

Thanks for the exciting presentation. Please what will the total wattage for the solar panel array be if it is to simultaneously power the total load through the inverter and at the same time charge the battery bank ?

Great . Thanks .

Hi Mam , may I know why for the array peak current must divide the peak sun hours?😁

Hi is another way to calculate how many solar panels need series or parrallel? In your example you mention 48v system / 24 v modules = 2 modules in series

All tutorials about PV arrays I've seen start by calculating the loads without saying anything about daytime or nighttime consumption. Your tutorials are far away the best we can find though, thanks for that! Am I wrong when I assume one has to size the battery bank to cope with the consumption at night and size the PV array to refill the batteries and cover the consumption during daytime. Let's say from your example, run the well pump at noon for instance? I've another question about batteries, when a battery is referred to as 200Ah, 20 hours discharge, shall we adjust the whole capacity like this (12-volt battery) Wh= 200Ah/24h*20h*12V=2000Wh instead of 2400Wh?

@AltEStore

8 жыл бұрын

+Bernard Deham When sizing the array, the time of consumption doesn't really come into play, the array needs to create enough power for the load, regardless of if it is used immediately or later. Yes, there is a little efficiency gained by not dealing with losses from storing it, but not enough to factor into the equation. However, that is a valid point, if you are using the power immediately instead of storing it, when you are calculating the battery bank, that can come into play. You can get away with a smaller battery bank if you don't store it. If you are going to be using the battery at a different discharge rate than it is listed at, you would need to check the specs of the battery to see what the capacity is at the discharge rate you are using. For example, if you are going to be using a C10 rate instead of C20, the capacity of the 200Ah battery may actually be 175Ah. You would use 175Ah for your calculations instead of the 200Ah. The battery specs usually have a chart or graph showing capacity at other C-rates.

What about the power needed to charge the batteries added to the running load during the day?

I have tried to search for the 4th video ( i.e How to size the charge controller and inverter) in your series designing an off-grid pv system but I cannot find it. Thanks for the information much appreciated.

@tomallen2915

3 жыл бұрын

Sorry I just found all the videos I was looking for

Hi Amy This is by far the best educational video I ever came across. I should have seen this while I was studying for renewable energy major. But it's never too late to ask a question. I was wondering when we design the array should we always base it on the load? Aren't we going to base it on Wh of battery bank? After all it's the battery bank that the array is supposed to charge? Will appreciate if you shed some light in this. Thank you

@AltEStore

4 жыл бұрын

Both the array and the battery bank are sized for the load. So by default, the array will be correctly sized for the battery bank.

@OmarMughal95

4 жыл бұрын

Aslam o alikum. Elaborating the altE Store's answer, Ihsan if you are worried about the bigger battery bank than there are following things that should be considered. 1) Battery Bank was designed keeping these predictable variables in mind (Video 2 of the series) a) DoD b) Inverter Efficiency c)Days of Autonomy d)Temp multiplier (Has no role in charging just changes the capacity size) So you would not need to recharge your complete battery bank on daily basis. and after considering all that a backup generator is added to cope with any other unpredictable variables. 2) The solar hours are taken on worst average of the year at 2.8 hours so that too will support the charging requirement. 3) The next factor was DC system efficiency which is kept at 67 % . So considering all these you would not size your PV according to battery bank size other wise it would of no use most of the year. Since your batteries will be at full capacity, and that would be a waste of resource.

what about the difference between poly and mono crystal cells? if you are going to wire three 20 volt panels in series for a 48 volt battery, would you run the that through charge controller like a classic to match the voltage? what about snow coverage, is there a charge controller that will warm up the panels to aid the slide to slide off? what about solar trackers to get better performance?why not over build the panels to produce more power and store to a bigger battery bank to be less dependent on genny? thanks john

@AltEStore

8 жыл бұрын

+Rev John O'Toole Rev John, Sorry about the delay, we missed this question. - We just released a video about the difference between mono and poly solar panels, you can see it here kzread.info/dash/bejne/hnelkq1sdM-slMY.html. - Yes, if wiring 3 panels in series for nominal 60V, you would run it through an MPPT charge controller to drop it down to the correct battery voltage. - MidNite Solar was working on a feature on their Classic charge controller to run the power backwards from the battery bank to melt the snow, but last I heard, that feature wasn't released. The most reliable way to help snow fall off is to install them at a steep angle. That helps maximize winter performance anyways, as the sun is lower in the sky during the snowy season. - We did a blog talking about the pros and cons of trackers, you can read it here, www.altestore.com/blog/2015/06/solar-tracking-tips-to-track-or-not-to-track/ . - The decision to oversize to reduce generator use is a tricky one. If you are in the middle of a week long storm, it would take a very large battery bank to give you a week of battery backup. At some point, it isn't cost effective to chase down every last kWh via solar, no matter how big your array is, if there's no sun, there's no power. However, if you are in a location that's good for wind, a wind turbine in combination with solar can be a great solution, as usually when the sun isn't shining, the wind is blowing. Especially during the winter.

is possible that operating hrs of the load is more then the average sun hrs?????

@AltEStore

6 жыл бұрын

Yes, as long as the load is smaller than the solar array. For example, if you have a 1000W solar array and 5 sun hours, in one day you'll make 5000 watt hours (before losses). After losses, you'll have about 3000Wh available. If you have a 100W load, you could run it for 24 hours, and still have leftover power. 100W x 24 hours = 2400Wh used.

hello, what about if i want to make battery charge and load work at the same time ? solar array sizing will be the same or what ?

@AltEStore

7 жыл бұрын

Once the batteries are full to begin with, if you are using 10kWh and making 10kWh (as with your question, not taking inefficiencies into consideration), then whether you use that power as it is being made vs using it from the batteries, you are using the same amount. Where needing the extra power generated comes into play more is if you have a rainy day that draws power from the batteries, then a sunny day, and then another rainy day, and so on. The solar array may not have had enough time to charge up the battery bank fully before you need it again. That being said, the calculator figures out the minimum size array you need, it is usually a good idea to oversize a bit to take various scenarios into consideration.

Hi, Let say I used all 2192Wh in just 1 whole night (means drawing all that power from bat only). then i want to charge it for 2.8Hr time (since its the worst case of sun hours and no other load connected).. do i just need to add more panel to my system.. like 8 pcs of PV.. 4 in parallel and connected to series to generate around 1260W..? is that amount of power enough to bring up my batteries again to use for the coming night? ^_^

@AltEStore

8 жыл бұрын

+Rolex Fredeluces Right. If you are using 2192Wh overnight, and have 2.8 sun hours to charge it back up the next day, you need enough solar to do that. 2192Wh / 2.8 sun hour / .7 system losses (varies depending on system) = 1118W of solar needed to charge battery back up next day. Depending on your panels and voltage battery bank, you could do something like four 300W panels, wired in two parallel strings of 2 in series. Here are some 320W 24V panels, www.altestore.com/store/solar-panels/solarworld-320-watt-solar-panel-sunmodule-sw320-mono-v40-frame-p11864/

@rolexfredeluces9927

8 жыл бұрын

+altE Store thanks a lot..

How do I know nominal voltage? In Datasheet of panel I am refering following specs are given maximum power (Wp = 225) , power tolerance (±3%), Vmp (26.66V), Imp (8.44A), Voc (33.60V), Isc (8.9A)

@AltEStore

7 жыл бұрын

Do you know how many cells are in the panel? Each cell is usually about 0.5Vmp. At 26.22Vmp, I'm betting it is a 54 cell, nominal 18V panel.

@zrakeshz1

7 жыл бұрын

altE Yes its 54 cell panel. You're amazing. Thanks.

you did the math according to the worst month of sun hrs. but what will we do if we need more power in the best sunny days(June/July). and need very less amount of power in worst days(January/Dec).

@AltEStore

7 жыл бұрын

Just use the sun hours for those months. You'll need a much smaller solar array.

I am not sure that the sizing procedure as shown will work. DUE TO SYSTEM LOSSES:
 The solar panels once they age will have losses of between 10% to 20%. The battery charger (whether it is a dedicated battery charger, an PWM, or an MPPT) will have losses of 5%. A lead battery bank will have losses of 25%. A battery inverter will have losses of 10% to 20%. 2,192 Wh x [(1 - 80%) + (1 - 95%) + (1 - 75%) + (1 - 80%)] = 1,534 Wh due to system losses

DUE TO % DOD

2,192 Wh x 50% DOD = 1,096 Wh due to 50% DOD

DUE TO TEMPERATURE MULTIPLIER WHICH COMPENSATES FOR LOST CAPACITY DUE TO LOWER TEMPERATURES

Then on top of this you have as you pointed out a temperature multiplier.

2,192 Wh x 1.19 = 416 Wh due to temperature multiplier

SUMMARY OF ENERGY REQUIRED

2,192 Wh energy demanded
1,534 Wh due to system losses
1,096 Wh due to 50% DOD 416 Wh due to temperature multiplier
5,239 Wh energy required to account for energy demanded, inefficiencies, % DOD, capacity loss due to low temperatures 

This implies a multiplier of 2.39 or 2,192 Wh x 2.39 = 5,239 Wh

SOLAR ARRAY SIZE

Winter sun peak hours are 2.8-Sun peak hours 

5,239 Wh / 2.8-h = 1,871 Wh size of solar array required 

NUMBER OF SOLAR PANELS, # OF SOLAR PANELS PER STRING, & # OF PARALLEL STRINGS

Solar panels of 250 Wp

1,871 W / 250 W = 7.484 solar panels or 8-solar panels

48 VDC / 20 VDC = 2.4 solar panels per string increase to 4-solar panels per string to be divisible into 8 8-solar panels / 4-solar panels per string = 2-parallel strings ISSUES This solar array will keep up with energy demand from house loads in the winter as calculated above; however, in the previous video, a battery bank was designed to store energy for 3-days along with the energy demand required for house loads. However, in IMHO this system will not suffice for the battery bank in the winter for more than one day. The above calculations provide sufficient energy for the house loads and for stored battery energy used for ONE day after accounting for energy system losses and compensation for lost capacity due to lower temperatures. The previous video designed a battery bank of 16,986 Wh for THREE days of energy storage. This will probably create problems inside the batteries since they will remain undercharged for several days during the winter, and as stated in that video it will require a generator. However, the generator might work best as a DC generator, and charge the batteries directly, or it will require a bidirectional inverter converting AC to DC to charge the batteries.

I got a 10W solar panel, whose specs are: Max Power = 10W Vmp = 18V Imp = 0.55A Isc = 0.6A Voc = 21.24V Max system voltage = 1000V According to the specs mentioned above, is this a nominal 12V solar panel? Because it has 70 cells total. Please let me know asap. Thanks.

@AltEStore

5 жыл бұрын

It is a 12V panel. They may have 2 parallel strings of 35 in series to make the right voltage.

@sanchezboy8654

5 жыл бұрын

@@AltEStore I also got a 5W solar panel, whose specs are: Max Power = 5W Vmp = 19V Imp = 0.3A Isc = 0.3A Voc = 23V Max system voltage = 715V According to the specs mentioned above, is this also a nominal 12V solar panel? Because it has 36 cells total (one array, consisting of 16 cells, is connected in series with another array, consisting of 20 cells). Please let me know asap. Thanks.

@AltEStore

5 жыл бұрын

@@sanchezboy8654 voc of around 22 or 23V is a 12V panel.

@sanchezboy8654

5 жыл бұрын

@@AltEStore thanks.

I am a little confused. From your "load" list you needed 2192 watts of power. When you divide by "efficiency" you have less power available that is needed. Seems the panels would have to have higher power output to provide the needed power.

@AltEStore

4 жыл бұрын

You need to include time into the equation. For example, 2000W of solar can generate 6000Wh of energy stored into a battery. You could run a 6000W load for an hour. The solar panels aren't running the loads directly. They are simply charging the batteries, that then provide power to the loads.

@andybrown3674

4 жыл бұрын

Guess I am just to thick headed to understand. Thanks for the time to reply.

Why efficency 0.67 We dont have battery

@AltEStore

4 жыл бұрын

Without a battery, the efficiency can be much higher. Perhaps 85%.

i have one doubt. in our calculation total system load is 2192 wh. that means solar panels must supply more than 2192wh. so why did u choose 1168 wh. please clarify it . thank you

@AltEStore

9 жыл бұрын

Faizal Ps You are confusing 2192 watt hours of the load, which is a quantity, and 1168 watts of the solar panels, which is an instantaneous output rate. If you watch the video, at 3:13 I go through the math to determine the size of the solar array needed. 2192Wh load ÷ 2.8 sun hours ÷ 0.67 for system inefficiencies = 1168 watts of solar panels needed.

@faizalps501

9 жыл бұрын

Thanks a lot for your reply. I got it. I was wrong. Anyway your video is really awsm and very helpful for beginners. Thank you again.

@johnkovic4486

7 жыл бұрын

Is this correct? I would have thought it should be 2192Wh load ÷ Inverter Eff. ÷ 2.8 sun hours ÷ 0.67 (system eff.) ?

@AltEStore

7 жыл бұрын

You are right, I forgot to mention the inverter efficiency. Thanks for the correction.

Amy, I am assuming you are a Electrical Engineer! I love your analysis, but just like my physics classes my eyes start to glaze over. The math I can follow you on, but I must really concentrate. I went through the series 3X. I am beginning to absorb it, but I would not be your best student on a midterm or final (C- to a D+). I don't want you to dumb it down but could use some real life examples. Also I like to see you... you are very easy on the eyes. Respectfully

@RR42636

4 жыл бұрын

You are seriously creepy. She is using real life examples.

Don't know where you live but your math says you use 63KWH per month. Average house in north america use 600-800 KWH per month. Your heading says "OFF GRID" so I think you should at least try t be realistic.

@AltEStore

8 жыл бұрын

+Trina McDonald This series of videos is to teach how to do the math, including figuring out how much power you need for your particular system. In the first video of the series, I did a loads list for an off-grid cabin. I have lights, a fridge, a radio, a well pump, and occasional power tool use, coming up with the 2192Wh a day. kzread.info/dash/bejne/qJig25qImNbKnaw.htmlm35s That is a very realistic loads list for an off grid cabin. While taking an "average" house off-grid is possible, it is a much bigger endeavor than most people realize. Going completely off-grid generally takes a lifestyle change, cutting your power usage dramatically. A more realistic example for learning purposes is for taking a cabin off-grid that already has low power consumption. Once the basics are learned, then you can apply them to whatever size system you need.