Suggestions for using "wasted" solar power?

[SJ-Chris]

Looking for suggestions...

How would you use ~150-250w of power for 8-10hrs per day so it's not just "wasted"?

I've got multiple RVs (Class C) and they each have 500w of solar panels, and 200AH of lead batteries. Most of the time, especially in the off-season, they are just sitting in uncovered storage (getting plenty of sunlight year-round). While in storage, the solar is on and the batteries are easily maintained at 100% by the solar (my RV standby draw with everything "off" is only about 0.3amps). The output from the solar charge controller goes to my batteries and a 2000w PSW inverter (which is always off unless needed while camping as it draws ~2amps in standby when on). The solar charge controller also has terminals for a load (pos/neg) such that the solar charge controller could power something else (in addition to maintaining the coach batteries) while it is collecting sunlight.

In order to maintain the coach batteries at 100% it probably only uses ~20w worth of the 500w of solar. Of course we all know it is next to impossible to actually get 500w out of 500w worth of solar panels, especially in the off-season. But certainly my 500w worth of panels must be generating 200-350w worth of power during off-season sunlight hours (I live in CA so most days even in winter are sunny).

It got me to thinking the other day... It sure would be nice if that "extra" solar power (not battery power) could be actually DOING something instead of just holding the batteries fully charged WHILE IN STORAGE. There is a load terminal (pos/neg) coming off the solar charge controller and I'm thinking about getting an inexpensive 300w inverter to connect to it. My understanding is it would only have power when it is coming from the solar panels, and NOT getting power from the batteries. So it is a way to harvest/use this "extra" solar power from my panels for probably 8-10hrs per day. The question then becomes, "What to do with this power?"

The RVs are not stored near my home, so there is no way to use the power on my home.

A couple ideas that come to mind, but just not sure if they are needed/worthwhile...

- Power a circulating fan. This would move air around in the RV to hopefully keep things fresh and dry. Not sure it is needed though (I haven't had any problems with smells, mold).
- Power a humidifier. This might help to keep moisture down inside the RV. I haven't had a problem with this, but seems like it couldn't hurt.
- Power a couple Ultrasonic pest (mice/rat/squirrel) plug-in repellents. I haven't had an issue with mice/rats/squirrel, but prevention is always a good idea. I did have one mouse about 3 years ago. Thankfully, there are a few outdoor cats near where I store my RVs.

Any suggestions on how you would use ~150-250w of power for 8-10hrs per day so it's not just "wasted"? Thought some of you might have some creative ideas.

Thanks!
Chris

[Cptnvideo]

SJ, I think all of us with solar on our RVs have that issue. I'm full-time. Some days I don't have enough solar and some days I waste it.
I recently added 2 more LFPs to help level out the +/-, but it will always be an issue to some degree.

[SJ-Chris]

pianotuna wrote:
Grit dog,

Ah but that depends on your point of view. If his rv storage was near home, he could, if nothing else, reduce his bill at not much cost. Or he could do net metering with the excess power.

If my RVs were stored at my home I would likely try to figure out how to tap into that excess solar. But my RVs are stored in a yard 1/2 mile away.

Currently my solar keeps my coach batteries and chassis battery topped off (easy as there is very little draw), and powers an alarm system on my RV (motion sensor inside RV, motion sensor pointing at my cable wrapped catalytic converter, and motion sensor in the large rear storage compartment). But all of that can probably be powered by ~30-50w of solar, and my RVs have 500w of solar. Hence this post...looking for anything useful to use the rest of that potential solar power while in storage.

-Chris

[Grit_dog]

pianotuna wrote:
Grit dog,

Ah but that depends on your point of view. If his rv storage was near home, he could, if nothing else, reduce his bill at not much cost. Or he could do net metering with the excess power.

You’re trying too hard here…
What’s he gonna do if they’re stored “nearby”. Run a mile of cable through everyone’s back yard to his house? Or go swap out batteries every day?

Cmon man…

[pianotuna]

Grit dog,

Ah but that depends on your point of view. If his rv storage was near home, he could, if nothing else, reduce his bill at not much cost. Or he could do net metering with the excess power.

[Grit_dog]

And apologies to SJ Chris as I’ve contributed to the de railmen’s of your thread since your query had nothing to do with net metering for multiple reasons.

[Grit_dog]

Lol.
Apparently it’s worth it in Saskatchetoon even though they only pay back wholesale rate.
And for the 5 whole states in the US, Cali, the leader in net metering is about to revise their program to pay back 75% less than they are under the current plan. (Or that’s what the solar energy rags are saying).
Typical, sucker people in at what they thought was a profitable scheme for them and then pull the rug….weird. Never woulda thunk that would happen.
Although I just learned today that there were only 5 states doing this. If this is/was viable and win win for the supplier and customer, why hasn’t it happened in the other sunny states?

PT Barnum was right again….

[valhalla360]

pianotuna wrote:

valhalla360 wrote:
- As an individual playing the system it makes great sense.
- In terms of the larger community system, it's an expensive way to generate power and your neighbors wind up subsidizing you.

I don't see how that can be said.

Most grid tied "sales" are at the wholesale rate. i.e. about 50% of what is charged by the electric utility company.

Most also "zero" the credit balance (if any) once per year.

The only power source that is cheaper than solar is wind. Wind does require more maintenance.

Must be different in Canada. Most places, you get the full retail price. Only recently has there been some pushback as solar starts pushing beyond a fraction of a percent.

As far as solar pricing:
- If you get net metering at retail prices, sure.
- If you are accounting for the need for backup power when the sun isn't shining, solar is still very pricey.

[RickLight]

This is a prime case of 'get the specifics', 'most doesn't matter!

Rates and policies vary widely!

[pianotuna]

valhalla360 wrote:
- As an individual playing the system it makes great sense.
- In terms of the larger community system, it's an expensive way to generate power and your neighbors wind up subsidizing you.

I don't see how that can be said.

Most grid tied "sales" are at the wholesale rate. i.e. about 50% of what is charged by the electric utility company.

Most also "zero" the credit balance (if any) once per year.

The only power source that is cheaper than solar is wind. Wind does require more maintenance.

[valhalla360]

Grit dog wrote:

pianotuna wrote:

Grit dog wrote:
I’d say you’re trying too hard to find a solution to nothing.
The libby EVers on this forum would tell you how you could sell it back to the utility company.
Just don’t ask them to run the numbers as to whether it’s feasible….lol.

I have run the numbers for a partial year. The return on the investment was over 4%. That number does not include any government grants. System was active starting in May.

One does have to have the cold hard cash to pay for the system.

You’re selling power from your RV batteries back to the electric company?

Fundamentally that doesn’t make financial sense to me. You’re saying you could purchase, build and operate your own solar powered system (like an off grid system except larger to power all the systems and conveniences of a typical home) cheaper than the utilities rates?

Interesting.

The issue is most net-metering plans effectively pay you full retail price for electricity...not the wholesale price that a typical electric producer would get paid.

So if you have a solar system already for the RV and can easily connect it to the grid, yeah, it can pay off.
- As an individual playing the system it makes great sense.
- In terms of the larger community system, it's an expensive way to generate power and your neighbors wind up subsidizing you.

[Grit_dog]

pianotuna wrote:

Grit dog wrote:
I’d say you’re trying too hard to find a solution to nothing.
The libby EVers on this forum would tell you how you could sell it back to the utility company.
Just don’t ask them to run the numbers as to whether it’s feasible….lol.

I have run the numbers for a partial year. The return on the investment was over 4%. That number does not include any government grants. System was active starting in May.

One does have to have the cold hard cash to pay for the system.

You’re selling power from your RV batteries back to the electric company?

Fundamentally that doesn’t make financial sense to me. You’re saying you could purchase, build and operate your own solar powered system (like an off grid system except larger to power all the systems and conveniences of a typical home) cheaper than the utilities rates?

Interesting.

[MrWizard]

I like the security system idea, maybe add a small battery to the security system, so it would be active 24/7 aka night, the camera use would be returned to the battery during the day

[pianotuna]

Grit dog wrote:
I’d say you’re trying too hard to find a solution to nothing.
The libby EVers on this forum would tell you how you could sell it back to the utility company.
Just don’t ask them to run the numbers as to whether it’s feasible….lol.

I have run the numbers for a partial year. The return on the investment was over 4%. That number does not include any government grants. System was active starting in May.

One does have to have the cold hard cash to pay for the system.

[SJ-Chris]

JimBollman wrote:
This is an expensive idea but might fit your uses. Buy a few so called solar batteries and swap them out to be used other places on a regular bases. I have 4kw of those batteries for use during short power outages at home. I just charge them from the wall but if I had a motor home with a bunch of solar sitting in the back yard I would store them there and swap them into the shop to use the power. My process now for longer power outages is to charge them with a generator so I don't have the generator running all the time. I have thought abut picking up some solar panels to recharge them but they are still on the maybe list.

Thanks for the suggestion. Thankfully, I do not have power outages at my home except on very rare occasions so I don't really have the need for backup batteries for that. In the event that my power was out for any annoying length of time, I can always bring my RV home and run the generator and extension cord to the house to power a few items.

-Chris