The Admin's Blog

By Pianotuna

Here I’ll try to present some options for solar, starting with a minimalist approach, and ending with full blown 100% off the grid.

A. Maintenance only system, with room for expansion:

15 watts of solar for every 100 amp-hours of battery storage.

Charge controller:

Grape Solar GS-PWM-40BT

Use nominally 12 volt panels and look for the cheapest price per watt.  Don’t forget shipping costs! My personal preference is for poly panels.


B. System for weekender:

Same charge controller as above. Add solar panels based on 60 watts per 100 amp-hours of storage.


C. System for nearly eliminating generator use except for running the roof air conditioner:

Same charge controller as above. Add solar panels based on 150 watts per 100 amp-hours of storage. Add a 2000 watt Prowatt pure sine wave inverter.


D. System for running 100% solar, no holds barred.

Move to a 48 volt battery bank, with Carbon Foam batteries, or if there is no cold weather use, LI technology.

Add a 48 volt DC to 12 volt DC converter to allow the regular 12 volt loads to be run. An alternative to that would be to continue to use the OEM converter, but that will be wasteful on the power side of life.

Populate the entire roof with panels, and if need be, build a rack to expand the possible harvest to 1920 watts. Add linear actuators to allow remote control of tilting the panels.

Install a hybrid inverter/charger.

It is not clear that the Grape controller can handle 48 volts. If it does then I’d still consider using it (apparently 12 or 24 only). Otherwise I’d stay within a particular “family”. For example, Victron offers charge controllers, and excellent inverter/chargers. There are some new offerings that offer an “all in one” approach where the inverter/charger is also the solar controller. There are other top notch firms, too, so please investigate what is available.


Everyone makes mistakes. Mine was building a system that left no room for expansion of the solar harvest. When I was part time, it worked wonderfully well–to the point where I did not even have a generator for nearly five years. Once I moved to full time, the system could not meet my needs. The cost of upgrading would have meant starting over from square one, and the cost of starting over would have been excessive. I chose to cave in, and get a Yamaha 3000 sIEB electric start generator, to which I added remote start. I only use about 4 tanks of fuel per year, as it is cheaper where I live to go somewhere that I can use shore power.

Here is a system intended for stationary use but which could be modified for use in an RV


Please feel free to contact me for clarifications on this series.




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melinda blount
Anonymous User
Reviewed February 15, 2017

Cold here carpathians

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