Need help with solar performance

[FormerBluffer]

I am looking for help figuring out why our solar setup is not working like it should. Our van is a Sportsmobile West 2019 build. We only get what seems to me to be a reasonable amount of solar charging on days when it is slightly overcast or hazy sunshine (and this isn’t consistently true). However, we usually don’t get any (or very minimal) charging on bright sunny days.

Here is what we have:

• 2 Relion Lithium Batteries
• Blue Sky Solar Boost 3000i Solar Charge Controller – although this looks like it was designed for AGM batteries, the documentation indicates it should work with lithium batteries as well.
• 2 @ 115w Zamp Solar Panels
• Relion Battery Indicator

Sportsmobile left all of the Blue Sky Solar Controller settings at their default values which seems to be consistent with the Relion Battery documentation. However, I have since changed 2 settings which I thought were more appropriate for lithium batteries based on the documentation:

• Float Charge Voltage (FLT) changed to “OFF” (default = 13.2)
• Battery Temperature Compensation (btc) changed to 000 (default = 500)

Neither of these changes seemed to have any impact on what results we are seeing.

Here is what I have generally observed from the solar controller display:

• Aux Out display light – Always on regardless of sun/clouds (off at night)

• Charge Status display lights:

o Float – Only on if there is more than negligible charging
o Absorption – always on (off at night)
o Bulk – always off
o Flashing Lights – Never (because there is no equalization with lithium batteries?)

• Display Readings:

o Volt/Amp – The Volt reading tends to be about 13.4, but I have seen it as high as 13.9. The Amp reading is often 0.0, but when I am getting some charging I’ve seen numbers in the range of 2.5 to a high of12.1, but it is mostly on the lower end of the range
o Volt – tends to be the same or very close to the Volt reading in Volt/Amp
o Amp Out – tends to be the same or very close to the Amp reading in Volt/Amp
o Amp In – is 0.1 whenever the Amp reading in Volt/Amp is 0.0. Otherwise, the Amp In reading is always lower than the Amp reading in Volt/Amp by around 20-25%. For example, when the Volt/Amp reading was 13.4/3.4, the Amp In reading was 2.5
o Aux Volt – is 0.0 whenever the Volt/Amp reading is V/0.0. Otherwise, it is the same or similar to the Volts

• On bright sunny days the face plate on the controller gets very hot (which I understand is normal).
• Hazy sunshine seems to work best, but this is not consistent.
• On days where there are periods of bright sunshine and overcast skies alternating throughout the day, as soon as there has been any period with bright sunshine there won’t be any more solar charging for the rest of the day regardless of whether the overcast skies return. Does this mean the system needs to reset itself at night?

Does anyone have any suggestions on what I should check or need to change? Thanks.

[1der]

A picture of the solar panel setup on the roof is very helpful as I have seen numerous shading situations that impact solar performance.

What model ReLion batteries?
Where are you located? Sun angles, temps, etc.
Confirming Zamp panels are rigid glass not flexible?

Your readings - are they with an active load? With sun out, turning on a load such as the microwave or a hair dryer should result in max input from the solar controller.
Correct - Lith = no equalization.
12.1 reading is about right for 2x115w panlels.

Hopefully Scalf77 will be along shortly

[boywonder]

Originally Posted by FormerBluffer

I have since changed 2 settings which I thought were more appropriate for lithium batteries based on the documentation:

• Float Charge Voltage (FLT) changed to “OFF” (default = 13.2)
• Battery Temperature Compensation (btc) changed to 000 (default = 500)

Where are you located?

Turn float back on... 13.2-13.4 range is fine.

With Float turned back on, run a high load item (like a microwave or water heater) when the sun is out........what are the output amps under this condition?

[boywonder]

...so as I was posting my response above 1der called me on the red phone....

Assuming that your Zamp panels are wired in series (quite likely since the Blue Sky controller is MPPT)......

Here is a potential problem....maybe.....:

The Zamp panels have an open circuit voltage rating of 23.8V, so wired in series they are 47.6V at STC.

The Blue Sky 3000i has a max recommended input voltage of 40V....although the absolute max input voltage is 50V.

..so it's possible that in direct sunlight overhead in July in AZ, etc that the controller could be overheating.......


From the Blue Sky manual.....


SELECTING PV MODULES
The 3000i is designed to operate conventional 12V 36 cell PV modules or higher voltage 60 cell modules. It is not intended for use with 72 cell
modules.


Your Zamp panels are 36 cell..wired in series makes 72 cell....

One potential easy fix is to wire the solar panels in parallel.



What is the highest float voltage setting on the Blue Sky controller?

[1der]

And to add from the Solar Boost 3000i manual:

PANEL TEMPERATURE AND THERMAL PROTECTION
Internal power control devices use the front panel as a heatsink. It is normal for the front panel to become quite warm to the touch when the 3000i is
operating normally. Front panel heating will be the greatest when the 3000i is processing either very high power or very low power. When mounted to a
vertical surface with good ventilation, the 3000i can deliver full output in an ambient temperature of up to 45°C (113°F). If an over temperature condition exists, the 3000i will simply cycle on and off to keep internal temperature within acceptable limits.

.....with good ventilation...... a pic of the mounting location of the SB300i might help, too.

Further to boywonder's post:

Connecting PV Modules
Before attaching PV wires to the 3000i confirm proper voltage and polarity. Measure PV module voltage with PV modules in the sun and disconnected from the 3000i. Confirm open circuit voltage is within the range of ≈ 18 – 35 volts and of the proper polarity. If PV open circuit voltage is outside this range confirm proper PV module selection and wiring.

[boywonder]

Wiring the panels in parallel should work fine.......Your maximum Voc voltage for the Zamp panels is is 23.8V.

[jonyjoe101]

I suspect you have voltage drop in your system. If the most volts you see is 13.8 volts that means the controller probably thinks the batteries are fully charged and is cutting back. During full sunlight you should see at least get 14.4 volts.

On my ecoworthy 20 amp mppt I had an over 1 volt voltage drop. I had to raise the bulk voltage setting to 15.5 volts (max setting) so that I can fully charge my lifepo4 to 14.6 volts. At 15.5 volts I was getting max amps from my 240 watt panel (as high as 15 amps when the battery was low and sun overhead).

I wouldnt connect the panels in parallel, you will loose too much amps. Your mppt controller needs 30 plus volts from the panels to work. If possible put a small fan to blow on the controller to keep it cool (thats what I did on my ecoworthy). The ecoworthy is only rated at 20 amps but I had it connected to my 365 watt panel and was able to get 23 amps out of it. Your solar boost 3000i should easily handle the max 12 amps from your 230 watts of panels.
You should get all your voltage readings directly from the battery terminals. Example, if the controller reads 13.8 volts, and your battery terminals read 13 volts, that means you have a .8 volt voltage drop. To fix you have to raise the bulk setting by .8 volts. Every .1 or .2 volts affects the max amps the controller will put out.
Every single controller I owned pwm or mppt had voltage drop, they all read too high (which means the controller thinks the battery is fully charged). I suspect thats your problem.

[Scalf77]

My first thought is what is your criteria or measurement for saying you have lack performance. Yes, you are correct I one of those kind of guys. Luckily for me, my controller gives me about 1.3kWh a day, sometimes a little less. For me it is given, I have a hard measurement to go by.

Now we get into other variables, such as the SOC of the battery. To get the most charge I would like to be able to keep the charger in Bulk mode or MPPT mode. In this case it will transfer as much power as possible all the time. If we get to absorption , we will start bringing the current level down slowly. If we get to float we won't use much at all.

Then we get into the consumables, or how much power is being used during the day, that won't make it into the battery but it was still energy produced by the Solar System. If your system is like mine, the hot sunny day may look like it should produce more power, but my refrigerator will use more. I could have two days with the exact same output, but if I was measuring how much SOC went up in my battery one may be much better than the other.

The other thing to remember is that as temperature goes up solar output goes down the panels or cells get very warm. The following snapshot contains some good data.



At the time I took this snapshot you can see that I have made my 1,2kWh of power again. Today might have been better but I had the solar off in the early morning. In any event I get shaded pretty early in the afternoon, as you can see at this point I am getting a charge current of 5.4 amps. You will also notice the battery is getting -2.4 amps, so in this case I am not keeping up with the consumables.

Other things to note from this is never get to my 290 watts of panels, today I am 222 watts for the peak. But if you look at the output of my irradiance meter you will see it never saw 1000 W/M² all day, my average 662, while my peak was 915. Also note the range of temperature on the test cell, (this should be close to your panel temps.)

Even with these tools I could be fooled with the 41.2 W/M² giving me 71.2watts of output (the test cell and rear panel are in the shade, the front panels have some sun).

So try to understand your criteria and what outside variables have on that criteria. You may find it isn't your solar performance

[FormerBluffer]

Thanks for everyone’s help.

It seems best to answer Scalf77 questions first since I agree it does make sense to 1st understand what my expectations have been regarding performance. When deciding on the design, we were looking for a solar setup that would generate about 75 AH on a nice sunny day. This was supposed to largely offset the energy usage of running the refrigerator, fan and light. These were just guesses on our part. Unsurprisingly, our actual experience has been that the usage is higher. When planning a trip, I now assume that our usage will be 120 AH/day (more on hot days and less on cold days).

We were guessing that on a nice sunny day we should get about 75 AH from the solar panel. The reason I feel we are lacking performance is that on sunny days it appears that we are typically getting little to no solar charging. I base this on looking at the Blue Sky Controller display which shows the total PV amp-hours produced since the last reset. Over the course of a day, the change in this number is often 0 (or 3 or less), even though there has been plenty of sunshine. I have always thought that this number represented the total AH generated by the solar panels that are then used to help recharge the battery. I guess I always assumed that the flow of electricity had to go through the battery first before being used elsewhere, but I understand that measuring the solar power generated is the same and beneficial whether it all goes to the battery or whether it is first used to meet the current electrical needs of the van and only the excess goes to charge the battery. Going directly to power an appliance means less demand on the battery and at the end of the day the battery charge level should be the same. My understanding is that the Blue Sky Controller display showing the total PV amp-hours produced since the last reset shows the total AH generated regardless of whether it is used directly to meet the current energy demands of the van or charging the battery. Therefore, if this number is zero (or something nominal), it means that no solar power was generated to either meet the current electrical needs of the van or charge the battery. However, if this number actually only represents the net AH left over after meeting the current demands of the van that are then available to charge the battery, I’ve fundamentally misunderstood the information and definitely need to re-evaluate my thoughts on performance.

Scalf77, I hope this makes sense.

Here are answers to some of your questions raised by 1der, boywonder and jonyjoe101. I’ll try to get pictures and more information tomorrow:

Picture of solar panel set up. I’ll take a picture tomorrow.

What model Relion Batteries: 2 @ 300Ah RB300

Location: We live in Montana. The vast majority of use has been in the northwest (Montana, Idaho, Washington, Oregon) and has been in every seasons so all different sun angles and temperatures. It seems that it is worse during hot weather, but that may just be me noticing it more on those days.

The readings are all with some load, but not a high load. Typical load is less than 7 amps (refrigerator, fan and lights). I’ve never looked at it when the microwave was running.

I’ll change the solar controller’s settings tomorrow to turn float back on to the default setting of 13.2. and will run the microwave to see what the output is.

I don’t know whether the Zamp panels are wired in series or parallel, but I also assume that it is in series. Would changing from series to parallel require running all new heavier wires to account for the higher amps coming from the solar panels?

Highest Float Voltage Setting on the Blue Sky Controller is 17.0 (range = 12.0 – 17.0)

I’ll take a picture of the mounting location of the Blue Sky Controller location tomorrow. As you will see, it is mounted inside an enclosed cabinet with no ventilation. Over-heating was one thing I had thought was happening, but I have not seen anything that looks to me like the controller cycling on and off to regulate the temperature. Would this be something I can see is happening?

I will check for a voltage drop.

I may be missing something obvious, but I am not seeing a setting in the Blue Sky Controller that allows me to change the Bulk Voltage.

Thanks again to everyone for their help

[1der]

Thank you for the detailed response. Pictures of the connections under the panels might be helpful as well.

Has this low/zero solar charging experience been since day one after SMB installed (retrofitted) the solar panel system?

Re Series / Parallel connections - in case you are not familiar:

Series will be one panel connected straight into the other panel. One wire from EACH panel will be what goes into the roof pass through. Panel 1 pos connects to panel 2 neg. Panel 1 neg and panel 2 pos go to the roof pass through.

Parallel will have two Y-connectors or 2-into-1 combiners before the pass through. Examples:


Another way to check this would be a voltage reading across the Solar Controller terminals FROM the solar panels (input) - any reading above 25 VDC would indicate an in-series installation. This should be done with good outdoor lighting.

My early in the game guess is the panels are wired in series and are exceeding the max allowed voltage on the controller causing the controller to shutdown. Bright sunny day = max voltage input from the panels. Hazy day = lower voltage which maybe just below the shut-off threshold. But, all that said I would still expect some cumulative current readings from early and late in the day before full sun.

Often overlooked: A solar panel is sending current to the controller whenever there is light on the panel. The controller has to decide if the batteries need charging or not. If not, the solar controller looks to dissipate the current via the heat sink. Poor ventilation around the controller plus a hot cabin (controllers are usually installed by SMB in the upper side rails) and now there is a possible controller shutdown due to overheat. Cycling on and off can be less than a second.

600Ah of Lith battery capacity is a lot!!

Wiring - check to see if the MC4 connectors on the solar panels are well connected. Also, check for an inline fuse on one of the wire runs.
I have seen these fuses create problems where voltage readings are present but there is so much resistance that the current cannot flow.

Let's see what you have pics wise. Keep in mind this could be a multi point problem.