Calculating for solar setup

[Alpha-y2k]

So I'm calculateing for a solar setup and using an online calculator, and was wondering how close or good it was.

Keeping in mind variables such as cloudy days, etc...I realise this is just and avg calculation to get an idea.

The site I am using is:
https://www.renogy.com/calculators

I have a tv that rates 10watts total max power consumption. So out of curiosity I plugged into that site the info of 10watts, 12 hours a day run time, 80% efficiency, and 4hours sun per day.

It then recommends me to a roughly 40 watt solar panel system setup, with a 20Ahr battery size.

So I'm curious, for those that are more electrical savvy than I am...... Is that site fairly accurate and safe to use that calculation?
I know it's not an exact science, and there are and can be a lot of variables, I just wanted a base to work with.

[Thomas A Cronquist]

Originally Posted by Alpha-y2k

So I'm calculateing for a solar setup and using an online calculator, and was wondering how close or good it was.

Keeping in mind variables such as cloudy days, etc...I realise this is just and avg calculation to get an idea.

The site I am using is:
https://www.renogy.com/calculators

I have a tv that rates 10watts total max power consumption. So out of curiosity I plugged into that site the info of 10watts, 12 hours a day run time, 80% efficiency, and 4hours sun per day.

It then recommends me to a roughly 40 watt solar panel system setup, with a 20Ahr battery size.

So I'm curious, for those that are more electrical savvy than I am...... Is that site fairly accurate and safe to use that calculation?
I know it's not an exact science, and there are and can be a lot of variables, I just wanted a base to work with.

Steve, I would go with 2 Renogy 100 watt panels and 1 or 2 Renogy 100 AMG battery's with a Epever 30 amp controller.
I would go youTube.
Search Will Prowse. Get his book. Will can steer you on a great basic set up. DYI 400 watt 12 volt Solar Power System. Beginner Tutorial.
This system would cost about $900.00 with every thing and wire.
Tom C

[Perryb67]

Originally Posted by Alpha-y2k

So I'm calculateing for a solar setup and using an online calculator, and was wondering how close or good it was.

Keeping in mind variables such as cloudy days, etc...I realise this is just and avg calculation to get an idea.

The site I am using is:
https://www.renogy.com/calculators

I have a tv that rates 10watts total max power consumption. So out of curiosity I plugged into that site the info of 10watts, 12 hours a day run time, 80% efficiency, and 4hours sun per day.

It then recommends me to a roughly 40 watt solar panel system setup, with a 20Ahr battery size.

So I'm curious, for those that are more electrical savvy than I am...... Is that site fairly accurate and safe to use that calculation?
I know it's not an exact science, and there are and can be a lot of variables, I just wanted a base to work with.

We wouldn't get two days of electrical use with a 40 watt solar panel and only 20ah battery. What do you do when you have 4-6 cloudy days?

My biased recommendation: an 80-100 watt portable, series 31 battery (95-120 ah's), a decent controller next to the battery to help eliminate line loss (NOT on the panel), and good, 10 gauge, copper wires.

Enjoy,

Perry

[Raspy]

I'm with Perry on this and there are several reasons why.

Group 24 through group 31 are common sizes of batteries and are available anywhere. They have a capacity of 70-125 amp hours, which will get you through periods of bad weather. Remember too, you should not discharge a lead acid battery to below 50%, so the capacity must be halved to get the real useable number.

Solar panels have ratings that are hard to achieve. For instance, a panel that tracks the sun will produce about 250% of one laid flat on the roof of the trailer. So you have to factor in this discrepancy to get what you need. This is part of the reason the suitcase systems are so nice, they set up at an angle facing the sun and can be adjusted during the day to get good performance.

Suitcase systems are very practical when getting started because they don't require mounting on the roof, or running wires in the trailer. And they can be in the sun when the trailer is in the shade. A common size is the Renogy 100 watt system. They are very nice and come with a controller installed on the back of one of the panels. Then all you need is to run a wire to your battery and clip it on, or plug it in. A heavy duty #12 extension cord makes a good cord for this. It is durable, flexible and coils up inside the suitcase when done.

I contend that usage will always rise to meet capacity. So you'll undoubtedly find other neat toys you want to run on solar. Maybe charge a drill, or play music, charge phones and a computer, or even charge a bicycle.

Bottom line: Start out bigger than you think you need to allow for inefficiencies, bad weather, 50% max discharge and future power demands. Start out with a common size battery that will be cheap and easy to replace or double up if you want more. Start with a suitcase that is a common size, known for quality, practical to use and larger than your minimum calculations.

A very nice starting point is a Group 27 or 31, 12 volt deep cycle battery, depending on your battery box size (the 31 is larger). Start out with a common suitcase system of 100 watts, with controller. Get a minimum #12 extension cord from a big box store to make your wire, and make it long enough to allow pointing the panel in any direction while still reaching the battery. 20 feet is plenty long enough for this, and it should not be longer than necessary.

Then use it and see how it goes. If you begin to want more, you'll see how much more you might want and can think about how to achieve it. If you upgrade, get an MPPT controller for greater efficiency. If you build a permanent mounted system laid flat, allow for the decrease in performance from its rating. Remember that if you do install a permanent system, you can always use the suitcase to supplement it, or work in the sun, if you park in the shade. Both systems can run at the same time. If you need more power, but find your battery is getting topped off every day, get a second battery first. Monitor your batteries state of charge by reading the "rested voltage". This might be done after the last load has been off for a while in the evening, or in the morning before charging begins. Get a battery chart to determine what 50% charge voltage is (about 12.2 volts). If your voltage is getting up to 14.5 each day and them settling to 13.2, or so, before the sun sets, you are not using all of the power you have and your battery is reaching full charge every day.

[DiverRod]

Thanks all for your excellent advice!