Affordable Solar -- How To Design and Install an Affordable Solar System

Everyone:
Thanks for the help and thoughts. It seems if you have the roof room without interfering with roof maintenance and safety, residential panels might be the way to go.
Still working on a lot of questions. I still have a lack of understanding when it comes to connecting panels in series v. parallel or both, dealing with voltage and amperage. Studying robmcqueen's link regarding connecting panels in series or parallel, the ending result is still the same with the same amount of wattage going into the solar charger, using the example in the link. It seems like parallel would be the best overall so if one panel goes bad or in the shade, the others are still doing their job over series. Besides for wattage, does different panels have different voltage output? I'm assuming you determine the solar charger you need after figuring out your panel setup? I'm trying to understand the numbers relationship on the solar charger with the panels.
With my four 12 volt 105 AH Safari lithium batteries and power usage, I'm thinking any where in the range of 900 to 1000 watts for the panels. Same panels without the thought of adding any, using my Honda generators as a backup as needed. Obviously for running the A/C.

In order to get the full rated power from the panels, they all need to have the same specs. If that is not possible, try to match the specs as close as you can. Another solution to mismatched panels is to use an additional controller.
My coach came with a single 300 watt panel that was over 700.00 to purchase more of. I was able to find some 120 watt panels that would match up pretty close to it when wired in series/parallel. When I decided to expand on that, those panels were discontinued, replaced by mono panels. That changed the specs so they were no longer as good match. So I used another Victron controller for the Mono panels. Multiple Victron controllers will synch with each other and act as one in use.

Do not discount the advantage smaller panels can have in that you can distribute them easier over the entire roof. This helps with shading issues in that some panels will most always be in the sun. The lower price per watt of residential panels will quickly be forgotten if you are stuck somwhere with shading issues. Unless you are sure that will never be a problem for your style of camping.

Do not close the door on future expansion. A lot of people find that solar is addictive.
As you can see, there is no right or wrong on a lot of this stuff. Just what is right or wrong for you.
 
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Everyone:
Thanks for the help and thoughts. It seems if you have the roof room without interfering with roof maintenance and safety, residential panels might be the way to go.
Still working on a lot of questions. I still have a lack of understanding when it comes to connecting panels in series v. parallel or both, dealing with voltage and amperage. Studying robmcqueen's link regarding connecting panels in series or parallel, the ending result is still the same with the same amount of wattage going into the solar charger, using the example in the link. It seems like parallel would be the best overall so if one panel goes bad or in the shade, the others are still doing their job over series. Besides for wattage, does different panels have different voltage output? I'm assuming you determine the solar charger you need after figuring out your panel setup? I'm trying to understand the numbers relationship on the solar charger with the panels.
With my four 12 volt 105 AH Safari lithium batteries and power usage, I'm thinking any where in the range of 900 to 1000 watts for the panels. Same panels without the thought of adding any, using my Honda generators as a backup as needed. Obviously for running the A/C.

I found this video helpful.

https://www.youtube.com/watch?v=OZvrTuhJhXs
 
I took the plunge and had the Multi Plus II setup installed with 6 - 200 watt panels. Two sets of three panels in series, tied together in parallel. With all the stuff on the roof and doing the measuring, I decided residential panels wouldn't work. A few questions:
1. Can I add one more 200 watt panel to one of the group of three panels? There isn't enough room to add a panel to both group of three panels.
2. I see on my Cerbo GX display, it shows the system is only hooked up to one leg of the 50amp system (Everything works). I would think it should be hooked up to both legs? Next week, when I plug into a KOA full 50 amp hookup, is that going to effect my ability to have 50 amps worth of power?

Thanks
 
I took the plunge and had the Multi Plus II setup installed with 6 - 200 watt panels. Two sets of three panels in series, tied together in parallel. With all the stuff on the roof and doing the measuring, I decided residential panels wouldn't work. A few questions:
1. Can I add one more 200 watt panel to one of the group of three panels? There isn't enough room to add a panel to both group of three panels.
2. I see on my Cerbo GX display, it shows the system is only hooked up to one leg of the 50amp system (Everything works). I would think it should be hooked up to both legs? Next week, when I plug into a KOA full 50 amp hookup, is that going to effect my ability to have 50 amps worth of power?

Thanks

Answer to your first question; no, adding an extra panel to one string will increase the voltage on that string and when they are tied together in parallel it will cause problems.

1,200 Watts is plenty of Solar. Depending on your usage and the size of your battery bank, you should be fully charged by noon if you have good Sunshine. Adding that extra panel will not make much difference.

Answer number 2; I am not familiar with the display of the cerbo GX, does it actually show energy flow for L1 and L2, or does it simply show energy flow represented by a single line? If the cerbo GX has L1 and L2 representation, then you might need to check your software settings. You might also want to verify that the Multiplus II that was installed in your coach was, in fact, the model with two 120v line outputs (I believe there is a model with only one 120v line output).

Answer number 3; when you plug into Shore Power, the Multiplus II has an automatic, internal transfer switch (rated at 50 amps) that will sense the incoming power and connect your coach directly to the incoming Shore Power.
 
Thanks for the info. The most wattage I’ve had in full sunlight has been 900 W one time. I know you don’t get the full wattage out of your panels. And if I’m not mistaken, a lot has to do with the angle of the sunlight on the panels. The display for L1 and L2 actually shows energy flow in watts. My display only shows energy flow for L1 and zero for L2. The person who did my installation will do some updates on the system tomorrow. I will follow up on him on a few of these things.

Thanks again.
 
Thanks for the info. The most wattage I’ve had in full sunlight has been 900 W one time. I know you don’t get the full wattage out of your panels. And if I’m not mistaken, a lot has to do with the angle of the sunlight on the panels. The display for L1 and L2 actually shows energy flow in watts. My display only shows energy flow for L1 and zero for L2. The person who did my installation will do some updates on the system tomorrow. I will follow up on him on a few of these things.

Thanks again.
If you are using the Victron Solar Charge Controller, the history tab at the top of the screen will show how much energy the Solar panels bring in each day, the history screen will also show your maximum wattage each day. Note: unless your batteries are low, and they still need Charge around noon, you will not see anything close to 1,200 Watts. This is because by the time the Sun is bright enough, and high enough, to irradiate your flat mounted Solar panels, your batteries are probably fully charged, so, they can not accept the full 1,200 Watts.

If you really want to test your system, drain your batteries to 50% SOC, or less, and turn off your Solar Charge Controller (and any other charging source) until just before noon. This should allow your batteries to accept the full 1,200 Watts of Solar, as well as let your panels generate their full potential power (or close to their maximum).

Under normal operation, your batteries are probably charged up before noon and noon is when your panels can produce their max Wattage. Consequently, you will seldom see 1,200 Watts of Solar generation from your system.
 
If you are using the Victron Solar Charge Controller, the history tab at the top of the screen will show how much energy the Solar panels bring in each day, the history screen will also show your maximum wattage each day. Note: unless your batteries are low, and they still need Charge around noon, you will not see anything close to 1,200 Watts. This is because by the time the Sun is bright enough, and high enough, to irradiate your flat mounted Solar panels, your batteries are probably fully charged, so, they can not accept the full 1,200 Watts.

If you really want to test your system, drain your batteries to 50% SOC, or less, and turn off your Solar Charge Controller (and any other charging source) until just before noon. This should allow your batteries to accept the full 1,200 Watts of Solar, as well as let your panels generate their full potential power (or close to their maximum).

Under normal operation, your batteries are probably charged up before noon and noon is when your panels can produce their max Wattage. Consequently, you will seldom see 1,200 Watts of Solar generation from your system.

My display panel constantly shows me the state of charge on my batteries. For example, this morning my batteries were about at 65% because I used my fireplace heater for a while in the morning since the furnace heater is cutting in and out. That brought the batteries down. so I know they are not charged. With that the solar panel watts haven’t been over about 865 watts or so with full sun. Yes, I’ve seen when the battery is at 100% charged and on float mode, The solar output has gone down to minimum.
 
My display panel constantly shows me the state of charge on my batteries. For example, this morning my batteries were about at 65% because I used my fireplace heater for a while in the morning since the furnace heater is cutting in and out. That brought the batteries down. so I know they are not charged. With that the solar panel watts haven’t been over about 865 watts or so with full sun. Yes, I’ve seen when the battery is at 100% charged and on float mode, The solar output has gone down to minimum.

My point is that your panels don't see "Full Sun" until almost noon on any given day. This is because your panels are almost flat. Given that your batteries were at 65% in early morning, your Solar panels started producing power about one hour after Sunrise, by noon, on a Sunny day your batteries would probably be fully charged. This is why you are seeing numbers like 865 Watts max on your system, because, the early morning Sun is not hitting your panels at the proper angle to produce more than 865 Watts and by the time the Sun is hitting your panels at an angle they can produce 1,200 Watts, your batteries are almost fully charged.
 
My point is that your panels don't see "Full Sun" until almost noon on any given day. This is because your panels are almost flat. Given that your batteries were at 65% in early morning, your Solar panels started producing power about one hour after Sunrise, by noon, on a Sunny day your batteries would probably be fully charged. This is why you are seeing numbers like 865 Watts max on your system, because, the early morning Sun is not hitting your panels at the proper angle to produce more than 865 Watts and by the time the Sun is hitting your panels at an angle they can produce 1,200 Watts, your batteries are almost fully charged.

I was in a large parking lot at 4:15 where the sun was full. My batteries were at about 82%. The solar panels were generating a little over 800 W. I’m guessing this had to do with the angle of the sun and position of my trailer to the sun at the time.
 
I was in a large parking lot at 4:15 where the sun was full. My batteries were at about 82%. The solar panels were generating a little over 800 W. I’m guessing this had to do with the angle of the sun and position of my trailer to the sun at the time.
IMG_7328.jpeg. Here’s the photo I meant to attach
 
With the increased availability of larger capacity batteries (200ah or more) I thought I would repost this response from another thread to help you avoid buying the wrong battery for your system. Note: a larger capacity battery is a valid choice, as long as it meets the amperage requirements of your system.

Maybe consider just one 200ah Li battery? No worries with extra wiring, different charge rates or such things. Won’t have a spare if one fails, but I don’t think that is likely.

Thanks for joining the forum.

If you do decide to go with the single 200ah battery, be careful that the Battery Management System (BMS) is rated to output 200 amps continuously. Most 100ah batteries are rated to output 100 amps, however, some manufacturers of 200ah or 300ah batteries use a BMS which are only rated for 100 amps output and not 200 or 300 amps which you would logically expect.

Where this matters is with your Inverter, they can draw more than 100 amps of power, and if your BMS limits the amperage to 100 amps, your Inverter will shut down (if you have two 100 amp batteries, they will both output 100 amps, for a combined 200 amps output).

By the way, the best way to install multiple batteries is to attach each battery to a Buss Bar and then attach the wires from the coach to the Buss Bar. This method allows each battery to contribute an equal amount to the load and to receive an equal charge.

Note: it can be confusing talking about Amps (Amperage) and Amp Hours (ah) because both numbers are 100 in this discussion. The battery storage capacity is called Amp Hours, in the case of a 100ah battery, the battery can supply 100 amps of energy for one hour (or it could supply 50 amps for two hours).

When we are talking about Amperage (Amps), we are talking about the Maximum Continuous amount of power the BMS will allow the battery to output. As an example: say your Inverter requires 180 amps to operate, a single 100ah battery with a Max output rating of 100 amps will not power your Inverter. However, if you have two batteries that are capable of supplying 100 amps each, now your Inverter will operate just fine. Now, if you chose a 200ah battery with a 100 or 150 amp Max output, your Inverter would not function because you don't have enough current (amperage) to feed your Inverter.
 
Thanks again folks, tons of great information. SOLARPOWEREDRV I particularly appreciate your post on installing a solar system in phases.
This winter I plan to replace the whole system, but for now will add two good LiFePo4 batteries which I can keep for the future setup.
 

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